Explanation of genetic terms and words

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SpecialCorns Johan
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Joined: 03 Feb 2008, 12:48

Explanation of genetic terms and words

by SpecialCorns Johan » 27 Nov 2008, 21:09

I know that this list is not complete.
And a huge thank to Douglas Green (Scotman) for his translation

Hope that you enjoy.
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:arrow: Allele

By a mutation is coming intoo a form of a gene, they have thier own set position on a Chromosome and carriers of a certain piece of Hereditary information. Each gene consists of several different possibilities, each possibility is called an allele. If an individual has 2 matching allele for a specific gene, this is known as homozygous. If the alleles are not matching this is known as heterozygous. Allele always come in pairs, basically they are just 2 different versions of the same gene.

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:arrow: Anerythristic A

Anerythristic A, Anery, Missing Red or Black Albino are all names for the Anerythristic A, this basically means that the Red colour pigment is missing. An- means without, and Erythrin is the name of the Red colour pigment, together it becomes Anerythristic, which is a Black/ Grey Snake. At the moment there are 3 different forms of Anerythrism in Corn Snakes, all of which will be explained later. Anery A is a Snake where only the Red pigment is missing, Black and Yellow are still visible. Usually the Yellow colour shows around the neck and sides of the Snake.

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:arrow: Anerythristic B (Charcoal)

Anery B or Charcoal
(Axanthin is seldomly used as a name,
A means without and Xanthin is the name of the Yellow colour Pigment ) means that not only the Red Pigment is missing, also the Yellow Pigment is greatly reduced.
These animals are almost completely Black and Grey, with virtually no visible Yellow

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:arrow: Anerythristic C, or Morph Z (Ashy/Cinder)

Anery C has a Burgundy Rusty colour with distinctive saddle borders. The saddles are a Fiery Red/ Orange colour.

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:arrow: Caramel

The Caramel gene is also considered to be a form of Anerythristic but not by everyone, some still consider it as a Wildform of a Corn Snake. The gene itself seems to have the same effect as the Anery A gene, the Yellow Pigment is enhanced and the Red Pigment is either greatly reduced or completely missing. The Caramel gene seems to be co-dominant, this is noticeable when you see the messy head patterns and the Yellowy ground colour of Corn Snakes that are heterozygous for Caramel, but it is not co-dominant, because its not 100% visible on all Snakes that are het for Caramel. It has a pale Brown - Goldy Yellow ground colour, with Caramel coloured saddle markings with a Black border.

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:arrow: Cells

The cells is de smallest unit of an organisation of living things that is build and have all genetics information of that organism
all plants, animals, mould and bactirial exist out of cells. The cells excist out more of cellmembrane, dat hold all of it together. The Cytoplasm contains a cell nuclues. The cytoplasm excist at his own of cytosol en cel organism. A cell nuclues.


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:arrow: Cellpadding (mitosis) en ( meiosis)

1. Somatische celpadding
The somatische celpadding of the usual cellpadding is continuous for live. The somatische cellpadding take care for new skin that is making for the shed en the wound can be heal.

2. reductioapadding

It begin with one simple impregnate egg cell. A impregnate egg cell ( a zygote) because of a male sperm cell with a female egg cell ( gamete). Before a gamete of the male they can melt together with a female gamete there must be first a partition of the propagation, because the animal out of that impregnation must be equal with the number of the chromosome pairs that possess with his parents! The numbers of chromosome defenite the sort? The next example make clear why the chromosome first must share. When a complete male sperm cell will be melt with a complete female egg cell, than the impregnate egg cell will contain (= zygote) twice time that number of chromosome. when such of a zygote will be develop there will be a complete other creature. Before the male sperm cell (= gameet) en the female egg cel ( = gameet) will be melt, there must be first een half( = reduction) of the numbers of chromosome!!!

As well as the male sperm cell and the female egg cell is into being out of the impregnate cells. The impregnate cell of the male as well the female contain een poolbody and a heartbody with in it a normal nimbers of chromosome.
The special of the impregnate cell is that it is not that these do not share themselves in a normal manner. This means that the cell division differs from reproduction cell from that of the somatic cell division. Just like the ordinary (=mitosis) cell division the pole corpuscle shares itself in 2 equal parts. And however in stead ofto the ordinary cell division, where the chromosomes under the influence of pool body in the length direction in halft,will the chromosomes pairs (=homologen chromosomes) exacty near eachother , where them mutual " particles chromosomen" to exchange!!!!!!!. After this exchange of " particles chromosoms" the chromosomes pairs (=homologen chromosomes) will go out of each other and moved to the pools of the cells. But the result is now, which only one chromosome of each couple one of the both ends of cell reach!!!!! Here it are therefore already stipulated because for animal we breed (and the hetrozygoten and homozygoten!!! 1st Photo ( mitose)
2nd Photo ( meiose )

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:arrow: Chromosomes


The word Chromosome comes from the Greek language:
Chroma = Colour, soma = body
The entire genome by Snakes is divided into several long nitrogen based chains in the cell nucleus.
Bases: The four letters of the alphabet that forms DNA are A (Adenine), T (Thymine), C (Cytosine) and G (Guanine). By RNA the letter U (Uracil) takes the place of T.
Base pairs: The bases form fixed pairs. A can only be paired with T and C only with G, by RNA it is A paired with U. These chains are called Chromosomes. They contain all the genetical information necessary for development, maintenance and reproduction of a Snake. Chromosomes are made up of DNA and some protiens, also known as Chromatin. This contains part of the hereditary information (DNA) in (multicellular) organisms. Each Chromosome containsa large number of hereditaty properties, each Chromosome contains genes, which act as links for different characteristics. Chromosomes always come in pairs ín cells, the 2 chromosomes of a pair are always the same which means they contain genes for the same hereditary properties. In reproduction cells there are no pairs of Chromosomes, just single chromosomes, there are also no gene pairs just single genes. This changes during fertilisation, then the simple Chromosome from the sperm and from the egg come together and this gives a double Chromosome again.
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:arrow: Cloaca

The cloaca (Latin: "sewerage ") is the opening in the body of some animals used for the discharge of different body waste material (Urine etc.) and genital dissidences (such as eggs). All birds, reptiles and amphibians have a cloaca. Animals with a placenta (the most of mammals) and bony fishes have specialised openings instead of a cloaca.

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:arrow: Cytoplasm

The cytoplasm is the parts of a cell that are enclosed within the plasma membrane. The cytoplasm together with the heart calls Protoplasm In eukaryotic cells the cytoplasm contains organelles, such as mitochondria, that are filled with liquid kept separate from the rest of the cytoplasm by cell membranes. The part of the cytoplasm that is not held within organelles is called the cytosol. The cytosol is a complex mixture of cytoskeleton filaments, dissolved molecules, and water that fills much of the volume of a cell. The cytosol is a gel, with a network of fibers dispersed through water. Due to this network of pores and high concentrations of dissolved macromolecules, such as proteins, an effect called macromolecular crowding occurs and the cytosol does not act as an ideal solution. This crowding effect alters how the components of the cytosol interact with each other. Outer low of the cytoplasma is the cell membrane, which looks all in cell remains. The cytoplasma exist from the cytosol (the liquid basis substance) and the organelles and inclusions which float. The cytosol exist from water, endosperms, RNA, amino acids (the construction toes of endosperms), sugars, ions, and a lot of other. The cytoplasma exist for to 95% 60 from water. The cytoskelet are a network of endosperms that also in the cytoplasma are themselves and among other things firmness and forms to cell.

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:arrow: DNA

Deoxyribonucleic acid or DNA
is the most important carrier of hereditary information in all well-known organisms. A DNA molecuul consists of two long strings of nucleotides, which bend themselves together to a double helix. The two strings have been linked to each other by so-called basepairs. A base pair links two opposite nucleotides with each other. The order of nucleotides is set in a strict sequence. Due to the fact that there are in principle an infinitate amount of sequences possible, the order of nucleotides can provide unique hereditary information. Normally the DNA is in all cells of an organism in the form of chromosomes. Chromosomes can contain millionsof basenpairs. By means of replication, the DNA in a chromosome is copied. The replication happens before the cell division starts. Thereby each cell gets a copy of the DNA, and can by means of the reproduction the DNA be passed on to the offspring. On a chromosome there are dozens to hundreds of genes. Genes are made up of one or more DNA sequences, and every gene can be decoded with help of one or more protiens. Protiens fulfill in and outside of the cells a very large number of biological functions.

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:arrow: Diffused

Diffused is actually a Pattern Morph because it is a Diffusing (fading and merging) of the pattern and not to do with the deep Red colour. The deep Red colour has been bred over the years with the help of selective breeding (we know the deep Red colour as Bloodred). Bloodred diffused is a very popular Morph due to its variability. Young Snakes have no pattern or a very blurred pattern on thier sides, they also have a plain (white) belly. The fading vor blurring of the pattern increases with every shed. Depending on the parents, some will also lose the pattern on thier back almost completely. Bloodred seems to be co-dominant but it is not!!! We see this in the blurred pattern and the typical Grey head by another Morph without this gene. These are known as outcrossed Bloodreds.

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:arrow: Dilute


Dilluted of Dillution
Is in fact a Enlisch word of clot, cloty, clotted
Sometimes we speak about redusing, bot that's not right
This is caused because the pigment cells in the skin together clotted to larger cells, as a result of which the colour reflection of the cells becomes differently (diluted or less deeply). The Dilute gene is also known as "Blue". Some breeders thought that it was a selectively bred Anery Motley, as it was found at first only in Anery Motleys. The next idea was that the gene was connected in some way with Motley, this also proved to be wrong. Now that several breeders also have Anery (Blue) Dilute in thier collection of Anery Motleys it is possible to see the differences. The first Blue Dilute with a normal pattern (therefore no Motley) was born in 2006, at Rob Stevens of Bayou reptile, that year he also produced the first Blue Dilute Striped. The name Blue Dilute is now accepted by most breeders as a common name. The Dilute gene is known also by mammals where the Dilute gene ensures that:
Black coloured animals turn a blueish colour
Brown animals become a sort of Lavender colour
Skin coloured animals turn yellowish
Grey animals become a pinkish colour
The Dilute gene, however, has a different reaction in comparison to the other Hypo genes. The Dilute gene produces another effect on the melanine (black and or dark pigment) than the other Hypo genes. Because it is proven that the Dilute gene is also possible with a normal pattern but still with the change in colour and the reduction in the melanine, we talk about a new gene! There are many Hypo looking Lavenders that have been proven no to be Hypo, perhaps it is also the Dilute gene.This is speculation and not yet proven in 2007. time will tell and we will keep YOU informed.

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:arrow: Diploid


Diploid cells are cells which contain 2 copies of each chromosome in the cell core (the male chromosome lines are not identical). The number of chromosomes is reflected with 2n. Each gene will occur therefore at least twice.

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:arrow: Dominant

A genetic property is Dominant when only one of the 2 allele (copies) of a gene (either from the mother or the father) is needed to give the Snake the appearance of the gene (phenotype).
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:arrow: Egg tooth

The Egg tooth is actually 2 teeth which grow together. These Egg teeth sit at the front of the mouth on the lips, they grow in a forward direction away from the mouth, unlike the other normal teeth that grow in the other direction. The egg teeth fall off shortly after use. The Snakes egg teeth are just as sharp as the normal teeth. These teeth are used to cut small slits into the leathery egg shell, so that they can have thier first look at the world around them. If the egg teeth are broken vor fall off too early, then the snake cannot get out of the egg on its own and will die.

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:arrow:Erythrine

Erythrine is the gene that is responsible for the Red colour pigment.

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:arrow: Phenotype

Phenotype means literally " appearance" and is based on the Greek Phainein = looks, showing.
The phenotype is the total of all perceptible properties (characteristics) of an organism. It is the result of the genetic construction (the genotype) of an individual and the influence of its surroundings. An example of this is the skin colour of people. These are partly stipulated by the genotype, but also influenced by the sun (the environment). In this case therefore also the surroundings have influence on the phenotype. The phenotype can be explained in one simple formula:
phenotype = genotype + influence from outside

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:arrow: Pheromones


Pheromones are a fragrance molecules which are released by the female during her fertile period. This is at its strongest just after the shed. They are released to attract males snakes that are ready to pair. Pheromones are taken in, like all other fragrances, by the tongue which then takes the Pheromone molecules to the Jacobsen organ in the mouth.

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:arrow: Gamete


Reproduction cells (gamete)are haploid cells, used for the sexual reproduction.
The cells of a male are called seed cells, and the female has an egg cell. Humans have X and Y chromosomes, the male XY and female XX, Y is dominant. By snakes its the other way around, the male has ZZ and female WZ, W is dominant.

When a seed cell and an egg cell from the same species come together, it forms a diploid cell which develops into a new organism carrying DNA from both parents.
The process of changing a diploid cell into a haploid cell is called meiose, and is a form of cell division. Through meiose a single diploid cell becomes 4 haploid cells.
Each of the resulting reproduction cells contains one of the 2 Chromosomes in it from each parent. The cell core then divides, mitose, 2 cells are formed with an equal amount of Chromosomes as the mother cell.


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:arrow: Gene

A part of the DNA molecuul from which a chromosome exists. A natural entity of hereditary information. A gene exists from introns and exons. Exons are responsible for the encoding, the information in introns return in the eventual gene product. A gene is a certain DNA order for 1 or several specific protiens. These protiens cause the hereditary property to become a visible expression, such as colour or pattern. Each gene has a fixed place (locus) on a chromosome. Genes come in pairs by snakes, the positions of the genes are on each homological chromosome the same. The two genes of a gene pair contain information for the same hereditary property. But this information does not need be right. Genes can appear in several apparition forms. This is why we speak from allele by appearance. The information on the two allele can be identical (homozygous) or nor identical (heterozygous).
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:arrow: Genotype

The genotype is the complete hereditary information of an organism. This information can be found in the genes in the DNA. The genotype is the collection of genes of the individual which have been inherited from both parents. The hereditary information is mainly stored in the chromosomes. This information is passed on by both parents to the descendants.

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:arrow: Haploid

Haploid organisms have, in comparison to diploid organisms, only one copy of every chromosome. This is reflected with n or 1n. Also cells can be haploid: a snakes reproduction cells are haploid.

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:arrow: Hemipenis

The hemipenis is the penis of a snake. Snakes have a long tail, which can cause some problems during the pairing act. For this reason their penis is divided, hemi means half. Because of this it is possible that they can choose to approach the femalefrom left or right side depending on how the female is positioned. If the pairing is disturbed, it can happen that the hemipenis gets stuck and cannot be retracted into the body. Sometimes this repairs itself automatically, but in captivity animals can be helped with a massage with a wet glove.

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:arrow:Heterozygous


A snake is Heterozygous for a certain characteristic, when it has 2 different forms (allele) of a gene. This means that it has two different copies for a certain characteristic that is positioned at a certain place (locus) on the chromosomes. If two heterozygous organisms pair with each other, they can reproduce thier own individual genes, which then combine in many different combinations. Because both parents are heterozygous for a certain character then some of the offspring will end up homozygous for this characteristic due t o the fact that one or more of the new combinations will have both identical forms of a locus on the allele.

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:arrow: Homozygous


A snake is homozygoot for a certain character if it has two identical copies of a gene in a chromosome couple. This happens when both parents pass on the same allele for a gene to thier offspring. As two homozygote organisms reproduce themselves, they can only pass on this gene and the offspring will also be homozygous.

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:arrow: Hypo

Hypo
Hypo basically means "less" or reduced.

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:arrow: Hypomelanistic


Hypo meant less or reduced and melanistic means black or dark pigment.
Normal wild coloured where nearly all black pigment has disappeared. Or Hypomelanistisch. This gene reduces the amount of Black vor dark pigment, as a result of which it is not visible vor at least not easy to see. The other effect caused by the hypomelanistic gene is that the red pigment becomes more intense, and the snake seems brighter. There are several Hypo type' s:
Hypo A
Hypo B Sunkissed large saddles, unusual head pattern, and dark clear checkers on the belly Hypo C lava also known as" transparant", and have " transparent" borders around the saddles
Hypo D Ultra
Christmas
Dilute
dilutes the colour
The photograph Right is Hypo A in the middle Hypo B and on the left Hypo C

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:arrow: Intermediate


If diploïd organism are heterozygous (two different allele for 1 gene) for a characteristic, then they can end up showing both genes, resulting in a mixed form of a gene (for example pink flowers, when there is one allele for red flowers and one allele for white flowers).
By the Pantherophis Guttata this is only possible with Ultramel (Ultra and Amel) and Motley ANS STRIPED)!!! because the Ultra gene lies on the same locus as the Amel gene (and Motley on the same as the Striped gen, ( By Ultramel) these 2 alleles are then mixed to produce Ultramel. And therefore they are NOT Co-dominant !!! This is called intermediate or additively. But it can also be that one of the two allele does not become visible. The characteristic that is visible is then called dominant and the characteristic that is not visible is called recessive.

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:arrow: Melanine

This is the gene responsible for the Black vor dark colour pigment.

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:arrow: Mutation

A mutation is a modification that appears in the DNA, this then changes the gene.

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:arrow: Lavender

The Lavender gene is actually also a type of Anery gene, which causes a more purple vor violett coloured snake. They have a Pale grey/ pink ground colour with large pink/ dark pink saddles, the eyes are ruby red. Unfortunately the Ruby eyes are not proven to be connected to the Lavender gene, some Lavenders do not have Ruby eyes.

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:arrow: Locus

Locus (plural: loci): Latin for ' place'.
Locus are used to indicate where a gene place is on a chromosome. Alternatives on the DNA sequence of locus are called allele.

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:arrow: Jacobsons organ


Jacobsons organ Jacobsons organ is organ that snakes use to smell, some lizards such as skinken and varanen also have this organ. It is the connection between thier nose and mouth, because both the tongue and a type nose are involved. The function of this organ varies in different species.A mammal inhales air and conducts these along the Jacobson organ. By reptiles it works differently; they put there tongue on which the aroma molecules are transported, and then the end of the tongue is placed in a cavity and brushes along the Jacobsons organ. The aroma molecules are then analysed by the brain, then evaporate, the brain reactions to the molecules are then remembered for the next time. The molecules which sit in the exhaled air of a prey animal are then recognised as such, and the hunt is opened. The aroma of enemies on the other hand causes a fright reaction and makes the animal alerter. By moving rapidly with the tongue, there can be more aroma molecules taken in, this explains why snakes always "tongue the air". If a snake becomes disturbed or stressed it cab be observed that they do this rapidly to get more information of thier surroundings.
A = eye
B = tear gland
C = nose cavity with fabric
D = internal nose opening
E = external nose opening
F = stuck out tongue
G = withdrawn tongue
H = body of Jacobson
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:arrow:Popping

By the popping method of determining the sex of a snake, the male hemipenis are pressed outside of the body. Only when the hemipenis become visible is it definately a male. It is possible that a snake contracts its muscles so that it is not possible to press the hemipenis out. Therefore you can only say that a snake is 100% male when the hemipenis have been visible.

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:arrow: Protoplasm

Protoplasm is the living contents of a cell that are surrounded by a plasma membrane. This term is not commonly used in modern cell biology. Protoplasm is composed of a mixture of small molecules.

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:arrow: Recessive

A genetic characteristic is recessive by diploid organisms when the characteristic only becomes visible when there are no dominant genes to be found. In diploid organisms, both copies of the chromosome must contain the recessive alternative of the gene, the organism is then homozygous recessive for this characteristic.

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:arrow: Probing

Sex determination by probing is done with a special "needle". The special needle vor probe is sterilised (with alcohol) and dipped in vaseline vor something similar. The probe is then carefully pushed into the cloaca, in the direction of the end of the tail, the snake must be held straight and the probe must also be kept straight. Due to the fact that the male hemipenis sits in the tail whilst pulled in, then it is possible to push the probe in further by males as by females (male= 4-8 scales, female 1-2 scales). This should only be done by people with experience vor under supervision of an experienced prober. It is easy to injure snakes by probing incorrectly, which almost always results in infertility(this is known as leak punctures). But lets not talk about such possibilities.
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:arrow: Xantine

This is the gene responsible for the Yellow colour pigment.

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:arrow: Zygote


The zygote or fertilised egg cell are the first stage correctly after the versmelting of an egg cell with a seed cell (fecundation). The zygote are diploïde cell which is formed from two haploïde warrants. Rapidly after the shaping starts the zygote with cell divisions and embryo is then called. .


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You don't have to confuse the truth with the opinion of the majority



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Hacky83
Posts: 501
Joined: 05 Oct 2008, 21:21

Re: Explanation of genetic terms and words

by Hacky83 » 27 Nov 2008, 22:21

:fw: :fw: :fw: absolut great job :IV: :DE:
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User avatar
eeji
Administrator
Posts: 9329
Joined: 25 Sep 2007, 21:12

Re: Explanation of genetic terms and words

by eeji » 27 Nov 2008, 22:30

:fw:

EXCELLENT post, :ty: :JvdD:

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SnakeLady1990
Posts: 41
Joined: 23 Aug 2010, 20:22

Re: Explanation of genetic terms and words

by SnakeLady1990 » 27 Aug 2010, 05:39

Love it...is there a way you can save posts to a favorites list for future references?

:ty: :ty: :ty: :ty: :ty:
1.0.0 Amel Motley Corn Snake ~Fanta Cee~
0.0.1 Amel Corn Snake ~Sun Glory~
0.1.0 Snow Corn Snake ~Still to be named~
1.0.0 Spider Ball Python ~Chocolate Drizzle~
1.0.0 Snow Stripe Corn Snake ~Still to be named~
0.1.0 Tremper Albino Leopard Gecko ~Neeko~
0.0.2 Baby Bearded Dragons ~General Lee and xXx~


1.0.0 Boyfriend, hahaha ~Korey~

slangenbroed
Posts: 72
Joined: 10 May 2008, 11:58

Re: Explanation of genetic terms and words

by slangenbroed » 27 Sep 2013, 09:07

Very nice job
I hope there is more to come :NL:

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Serpentine
Posts: 438
Joined: 09 Feb 2013, 09:19

Re: Explanation of genetic terms and words

by Serpentine » 27 Sep 2013, 12:31

found a word that was not yet translated from dutch to english :)

Zygote
The zygote or fertilised egg cell are the first stage correctly after the versmelting(=fusion) of an egg cell with a seed cell (fecundation). The zygote are diploïde cell which is formed from two haploïde warrants. Rapidly after the shaping starts the zygote with cell divisions and embryo is then called. .


There are some others as well,do you want me to search them all? :| ^^
Serpentine

1.1 Lampropeltis alterna - juno road locality
1.9 Pantherophis guttatus - various morphs
1.0 Orthriophis taeniurus taeniurus - Calico
0.1 Elaphe climacophora - Kunashir Stripe

P.Guttatus te koop/available

Projects: Xanthic Snow Motley & Ultramel Anery Caramel Motley // Sulfur Tessera & Gold Dust Tessera
Searching for: Ultramel Pied // Gold Dust Stripe het or homo diffused

paulh
Posts: 23
Joined: 31 Dec 2008, 23:33

Re: Explanation of genetic terms and words -- revised & expa

by paulh » 14 Oct 2013, 17:13

Some of the original post is hard to understand. Here is a version with less fractured Dutch, some corrections, and a few extra words.

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Image Allele

All alleles are genes, but not all genes are alleles.

An allele is any one of a series of genes with the same location (locus) in a cell's chromosomes. Alleles have slightly different DNA sequences. The difference may be as small as the loss, gain, or change of one nucleotide pair.

A gene pair is made up of either two alleles (a heterozygous gene pair) or two copies of one allele (a homozygous gene pair). If two genes cannot make a gene pair, they are not alleles.

Graphic: A pair of homologous chromosomes. Each chromosome contains a double helix molecule of DNA. Gene B and gene b are alleles. Gene B and gene a are not alleles.
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Image Anerythristic (slang: anery)

The name of a mutant gene. The anerythristic gene is recessive to the corresponding normal allele in the corn snake. Obsolete names for this gene include anerythristic A, missing red, and black albino.

An- means without, and erythrin means the red/orange colour pigment. An anerythristic corn snake lacks the normal corn's red pigment. This leaves the snake coloured in shades of black and gray with some yellow along its neck and sides. This was the first mutant gene found that eliminates the red colouration. Although charcoal and other mutant genes also affect the red colouration, the different mutants seem to affect different parts of the biochemical mechanism producing the normal red colouration. See also charcoal, cinder, and caramel.

Graphic: Anerythristic corn snake
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Image Anerythristic A (see Anerythristic)

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Image Anerythristic B (see Charcoal)

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Image Anerythristic C (see Cinder)

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Image Caramel

Caramel is the name of a mutant gene. Genes named caramel occur in the corn snake and other species. Usually a caramel gene is recessive to its normal allele, as in corn snakes.

Caramel corn snakes are coloured in shades of yellow and yellowish brown. The ground colour varies from brown to yellow. The dorsal blotches are a caramel colour with black borders.

Some heterozygous caramel corn snakes have irregular head patterns and a ground colour that is a little more yellow than in normal snakes. However, not all heterozygous caramel corn snakes have these characteristics. That is why the gene fits the definition of a recessive mutant gene better than it fits the definition of a codominant mutant gene.

The caramel mutant gene's role in colour production has not been determined. It may prevent red pigment from forming while enhancing the formation of yellow pigment. Or it may change the colour by simply reducing the amount of red/orange pigment formed. Or it may do something else. While several mutant genes change or prevent formation of the normal red colouration, the different mutants seem to act on different parts of the biochemical mechanism. See also anerythristic, charcoal, cinder.

Although the caramel mutant gene occurs in some wild populations of the corn snake, caramel is not a wild type gene. See mutant, wild type.

Graphic: A caramel motley corn snake.
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Image Cell

A cell is the smallest unit of organization in a living thing. A cell holds all of an organism's genetic information and may be capable of living alone. Most bacteria and protozoans are single cells. Reptiles, trees, and other living things are made of many cells living together.

A cell is made up of the nucleus, cytoplasm, and cell membrane. The nucleus contains the chromosomes that hold most of the genetic information. The cytoplasm contains the organelles that make up the cellular machinery. The cell membrane forms the cell's outside surface. It holds the cell together and protects the cell's interior from the external environment.

Graphic: A cell.
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Image Cell division (mitosis and meiosis)

A one-celled zygote divides by mitosis to become a two-celled embryo. After many more mitotic divisions, the embryo becomes an adult. The adult produces sperm or egg cells by meiosis. A male's sperm fertilizes a female's egg to produce a zygote. And the process begins again.

1. Somatic division (mitosis)

Mitosis is the type of cell division used when the one-celled zygote becomes a two-celled embryo. Mitosis produces skin cells, muscle cells, and all other body cells except sperm or egg cells.

During mitosis, the chromosomes arrange themselves on the old cell's midline. The X-shaped chromosomes finish dividing lengthwise and become two rod-shaped chromosomes. One migrates into each half of the old cell. The cell membrane pinches in and separates the old cell into two smaller cells (cytokinesis). Both daughter cells have the same number of chromosomes as the parent cell. See a biology text for a more detailed description of mitosis.

2. Reduction division (meiosis)

Meiosis consists of two cell divisions that produce sperm or egg cells (gametes). The two divisions produce four gametes from one original cell. Meiosis is also known as reduction division because sperm and eggs have only half as many chromosomes as the original cell.

In the first cell division, the chromosomes are X-shaped because they are dividing. The chromosomes arrange themselves into homologous pairs along the cell's midline. The two chromosomes in each pair are either identical or are much more similar to each other than to any other chromosome. Homologous chromosomes can swap pieces -- crossovers. Each of the two daughter cells gets one chromosome from each homologous pair. Each of a corn snake's body cells has 36 chromosomes. After the first division of meiosis, each daughter cell has 18 X-shaped chromosomes.

In the second cell division, each X-shaped chromosome finishes dividing lengthwise and becomes two rod-shaped chromosomes. One migrates into each half of the cell. The cell membrane pinches in and separates the cell into two smaller cells, the gametes. Both gametes have the same number of chromosomes as their parent cell. Our corn snake's gametes still have 18 chromosomes. See a biology text for a more detailed description of meiosis.

A sperm fertilizes an egg to make a zygote. The corn snake sperm's 18 chromosomes are added to the egg's 18 chromosomes. This gives the zygote 36 chromosomes (18 homologous pairs), the same number as the parents. When the homologous pairs of chromosomes are reestablished, gene pairs are also reestablished.

Graphic: The phases of mitosis.
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Graphic: Meiosis
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Image Cellpadding (See Cell division)

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Image Charcoal

Charcoal is the name of a recessive mutant gene in the corn snake. Obsolete names include anerythristic B, anery B, axanthic (rare) and axanthin (rare). A- means without and xanthin refers to the yellow colour pigment.

In charcoal corn snakes, the red pigment is missing, and the yellow pigment is greatly reduced. These animals are almost completely black and gray, with virtually no visible yellow. Babies look much like baby anerythristic corn snakes. While charcoal, anerythristic, and other mutant genes affect the red colouration, the different mutants seem to act on different parts of the mechanism producing the red colouration. See also anerythristic, caramel, cinder.

Graphic: A charcoal corn snake.
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Image Chromosome

The word "chromosome" comes from the Greek language: chroma = colour, soma = body. The chromosomes are found in the cell nucleus. Each species has a characteristic number of chromosomes, which is usually fewer than 100 per nucleus. Corn snakes, for example, have 36 chromosomes.

A chromosome is made up of a double helix DNA molecule and the DNA molecule's protein support, which are known collectively as chromatin. The chromosomes contain almost all of the DNA in a cell. The rest of the DNA is in the mitochondria in the cell's cytoplasm.

Each chromosome's DNA molecule contains a large number of genes. A very simple definition of a gene is the DNA that contains the genetic code needed to produce a protein. Genes contain the information necessary for an organism's development, maintenance and reproduction.

The body cells of most multicellular living things contain chromosomes that can be arranged into homologous pairs. Aside from the sex chromosomes, the chromosomes in an homologous pair are always far more similar than chromosomes from different pairs. One member of a gene pair is in one chromosome of the homologous pair. The other member of the gene pair is in the other chromosome.

Homologous pairs are not connected or even associated during most cells' lives. Chromosomes only become arranged in homologous pairs during meiosis, when the sperm and eggs are formed.

A chromosome in the shape of an X is not a pair of chromosomes. It is a chromosome that is dividing into two chromosomes.

Sperm cells contain only one chromosome from each pair of the father's chromosomes. Egg cells contain only one chromosome from each pair of the mother's chromosomes. As one member of a gene pair is in each member of a chromosome pair, sperm and egg cells also contain only one gene from each parent's pair of genes. When a sperm and egg unite to make a zygote, the chromosome pairs (and gene pairs) are reestablished.

Graphic: X-shaped chromosomes. They divide in the second cell division of mieosis.
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Graphic: An X-shaped chromosome with part of the DNA molecule stretched out. (See DNA.)
Basenpaar = A base pair
DNA-dubbelstreng = A DNA molecule, showing the double helix structure.
Histonen = Histones, small proteins bound to the DNA molecule

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Image Cinder

Cinder is the name of a recessive mutant gene in the corn snake. Obsolete names include anerythristic C, anery C, morph Z, and ashy.

Cinder corn snakes have a burgundy ground colour with distinctive saddle borders. The saddles are a fiery red/orange colour. While cinder, anerythristic, and other mutant genes affect the snake's red colouration, the different mutants seem to act on different parts of the mechanism producing the red colouration. See also anerythristic, caramel, charcoal.

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Image Cloaca

Cloaca is a Latin word meaning sewer. The cloaca is located at the rear end of the intestine and terminates at the vent. The intestinal, urinary, and reproductive systems discharge into the cloaca. Material in the cloaca passes through an opening (the vent) to exit the body. Birds, reptiles, and amphibians have a cloaca and a vent. Bony fish and almost all mammals have their intestine separated from the urinary and reproductive systems. These animals do not have a cloaca.

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Image Codominant

1. One of the three dominance relationships. (See Dominance relationships.)

2. Possessing a gene pair made up of either a dominant mutant gene and a normal gene or a codominant mutant gene and a normal gene. Only herpers use this definition. It should be strongly discouraged in favor of standard genetics terms. (See Heterozygous.)

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Image Cytoplasm

The cytoplasm is part of a cell. It includes everything inside the cell membrane except the nucleus. For more information, consult a biology textbook.

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Image Deoxyribonucleic Acid (see DNA)

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Image Diffuse

Diffuse or diffused is the name of the pattern mutant gene that is commonly found in bloodred corn snakes. The gene seems to fit the pattern of a recessive mutant gene better than that of a codominant mutant gene.

Bloodred corns often have a ground colour that is as deep a red as the dorsal blotches. This red colouration is a product of selective breeding and is not a product of the diffuse mutant gene.

The diffuse gene causes the dorsal and lateral blotches to fade. Young snakes have no pattern or a very blurred pattern on the sides. The belly is plain white instead of being checkered, though some black dots may remain. The blurring of the pattern increases with age. Some snakes may nearly lose the pattern on the back. The pattern on the top of the head is also stretched.

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Image Dilute (AKA diluted, dilution)

The definition of dilute is to thin down or weaken, as by mixing with water or another liquid. A diluted colour is not as dark as the original.

The dilute gene is also known as "blue". Some breeders thought that it was a selectively bred anerythristic motley, as it was found at first only in those snakes. The next idea was that the gene was connected in some way with motley, but this also proved to be wrong. Now that several breeders have anerythristic (blue) dilute snakes in their collection of anerythristic motleys, it is possible to see the differences. The first blue dilute with a normal pattern (therefore no Motley mutant genes) was born in 2006, at Rob Stevens' Bayou Reptile. That year he also produced the first blue dilute striped. The name Blue Dilute is now accepted by most breeders as a common name.

Genes with a similar dilute effect occur in mammals. Black areas turn a bluish colour, and brown areas turn a lavender colour.

There is speculation that the dilute gene is the same as the lavender gene. As of 2007, this has been neither confirmed not denied.

Graphic: a dilute anerythistic motley corn snake
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Image Diploid

Diploid cells have chromosomes that can be arranged into homologous pairs. (See chromosome.) The variable n is the number of homologous pairs, and 2n is the total number of chromosomes. In the corn snake, n = 18, and 2n = 36.

Diploid cells produce more diploid cells by mitosis. Diploid cells in the adult testes or ovaries produce haploid sperm or egg cells by meiosis.

Graphic: A haploid sperm cell fertilizes a haploid egg cell to produce a diploid zygote.
cigoto = zygote
diploide = diploid
fecundacion = fertilization
haploide = haploid
homologos = homologous chromosomes
nucleo del espermatozoide = nucleus of the sperm
nucleo del ovulo = nucleus of the egg
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Image DNA (Deoxyribonucleic Acid)

DNA is the most important carrier of hereditary information. It is found in a cell's chromosomes. A double helix molecule of DNA is made of two spirals with base pairs forming crossbars. The molecule looks like a ladder that has been twisted lengthwise.

Each spiral is made of repeating sugar and phosphate groups. A base is attached to each sugar group. The four possible bases are adenine, cytosine, guanine, or thymine. A phosphate group and a sugar group, plus the attached base, make up a nucleotide. The base in each nucleotide in one spiral forms hydrogen bonds across the middle of the DNA molecule to the corresponding nucleotide in the other spiral. This holds the two halves of the molecule together. There are only two possible base pairs -- adenine (A) with thymine (T) and cytosine (C) with guanine (G). An adenine and thymine base pair can be either A-T or T-A. A cytosine and guanine base pair can be either C-G or G-C. Those four possible pairs can occur in any order along the DNA molecule. (See also gene, chromosome.)

Most multicellular organisms have between 100,000,000 and 10,000,000,000 base pairs in their DNA. Big numbers invite simplification. Every nucleotide has the same sugar group, the same phosphate group, and only one of four bases. One letter for the base can stand for the whole nucleotide. Mandatory pairing of bases means that specifying one nucleotide automatically specifies the complementary nucleotide. A letter sequence like ACGGTAC could fill a page if the molecule's complete chemical structure was drawn out.

DNA replication occurs before any indication of cell division is visible. As the two nucleotide strands in a DNA molecule begin to separate, new copies of the complementary nucleotides move into place along each strand. The two daughter DNA molecules are nearly complete before the two original nucleotide strands finish separating. One copy of the DNA molecule is in each half of an X-shaped chromosome.

The words "paired DNA strands" can be confusing because meaning depends on the context. They could mean the two strings of nucleotides in a single DNA molecule. Or they could mean two complete DNA molecules. Paired DNA strands in a zygote refers to two DNA molecules. One molecule is in the chromosome that the father contributes to a homologous pair in the zygote, and the other molecule is in the chromosome the mother contributes. Paired DNA strands in a zygote does NOT mean that a nucleotide strand from the father and a nucleotide strand from the mother have joined to make a single DNA molecule.

Graphic: A double helix DNA molecule.

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Image Dominance relationships

A dominance relationship always involves two alleles. One allele is dominant or recessive or codominant to the other. For simplicity, terms like "partial dominant", "incomplete dominant", "semidominant", "overdominant", etc. are considered synonyms of "codominant".

Two alleles, symbolized A and a, can make three gene pairs -- AA, Aa, and aa. These three gene pairs can produce either two phenotypes (A and a) or three phenotypes (AA, aa, and Aa). Dominant and recessive alleles have the two phenotype pattern. Codominant alleles have the three phenotype pattern.

The two phenotype pattern:
Phenotype range = __1________2___

Genotype AA produces phenotype A, at position 1.
Genotype Aa produces phenotype A, at position 1.
Genotype aa produces phenotype a, at position 2.

In the two phenotype pattern, the effect of the A gene in the Aa genotype dominates that of the a gene. Therefore, the A gene is dominant to the a gene. The effect of the a gene recedes into invisibility when the A gene is present. Therefore, the a gene is recessive to the A gene.

The three phenotype pattern:
Phenotype range = __1___2____3____4___5__

Genotype AA produces phenotype AA, at position 2.
Genotype aa produces phenotype aa, at position 4.
Genotype Aa produces phenotype Aa, at position 1 or 3 or 5 or both 2 and 4.

In the three phenotype pattern, both genes in the Aa genotype influence the phenotype. Gene A is codominant to gene a, and gene a is codominant to gene A.

Use of standards is common around the world. Defined standards include the meter, the gram, the equator, zero longitude, the second, etc. Geneticists use wild type as the standard (see wild type), but many texts have not adopted the practice.

When using the wild type standard, a mutant allele is dominant, recessive or codominant to the standard (wild type) allele. The standard allele is just the standard. It is not dominant, recessive or codominant to the mutant allele. In the same way, a standard meter is the standard, and the stick in my hand is longer, shorter, or the same length as the standard meter.

By convention, calling a gene a dominant mutant gene means that the mutant gene is dominant to the wild type allele. The wild type allele is understood and need not be specified. Calling a gene a dominant gene simply means the gene is dominant to another allele, and the second allele must be specified. Or if useage is uncertain, both alleles should be identified.


Pedigree of a dominant mutant gene:
Dominant mutant gene = A
Normal gene = a
Three possible genotypes = AA, Aa, aa
Mutant phenotype = red font color = AA and Aa. The AA and Aa genotypes produce the same mutant phenotype.
Normal phenotype = black font color
_______________AA x aa
__________________|____________
_____|_________|____|__________|
AA x Aa________Aa x Aa_________Aa x aa
___|______________|_______________|__
|_____|____|____|____|____|____|_____|
Aa____AA x AA___Aa___Aa___aa x aa____Aa
_________|___________________|
_________AA__________________aa

Pedigree of a recessive mutant gene:
Normal gene = A
Recessive mutant gene = a
Three possible genotypes = AA, Aa, aa
Mutant phenotype = red font color = aa
Normal phenotype = black font color. The AA and Aa genotypes produce the same normal phenotype.

_______________AA x aa
__________________|____________
_____|_________|____|__________|
AA x Aa________Aa x Aa_________Aa x aa
___|______________|_______________|__
|_____|____|____|____|____|____|_____|
Aa____AA x AA___Aa___Aa___aa x aa____Aa
_________|___________________|
_________AA__________________aa

Pedigree of a codominant mutant gene:
Codominant mutant gene = A
Normal gene = a
Three possible genotypes = AA, Aa, aa
Homozygous mutant phenotype = red font color = AA
Heterozygous mutant phenotype = half red font color = Aa
Normal phenotype = aa
Each genotype has its own phenotype.

_______________AA x aa
__________________|____________
_____|_________|____|__________|
AA x Aa________Aa x Aa_________Aa x aa
___|______________|_______________|__
|_____|____|____|____|____|____|_____|
Aa____AA x AA___Aa___Aa___aa x aa____Aa
_________|___________________|
_________AA__________________aa

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Image Dominant

1. One of the three dominance relationships. (See Dominance relationships.)

2. Not recessive. It is not known whether a mutant gene is a dominant or codominant mutant. (See Dominance relationships.)

3. Possessing a gene pair made up of two copies of a dominant mutant gene or two copies of a codominant mutant gene. Only herpers use this definition. It should be strongly discouraged in favor of standard genetics terms. (See Homozygous.)

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Image Egg tooth

The egg tooth is formed by the fusion of two teeth and is located at the front of the upper jaw. It is like the ordinary teeth in structure, but it is larger and curves forward, out of the mouth, instead of back. The edges are flattened and razor sharp. The egg tooth is used to cut slits in the leathery egg shell, and the baby snake leaves the egg through one of these slits. The egg tooth falls off shortly after hatching. If the egg tooth is broken or falls off too early, the snake cannot get out of the egg and will die.

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Image Erythrin

Red colour pigment. There is no single gene responsible for making red pigment. Many genes work together as a team. The team includes the normal allele of the anerythristic mutant gene, the normal allele of the charcoal mutant gene, the normal allele of the caramel mutant gene, the normal allele of the cinder mutant gene, etc.

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Image Erythrine (see Erythrin)

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Image Gamete

The collective term for the male's sperm cells and the female's egg cells. Meiosis is the type of cell division that produces gametes.

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Image Gene

A portion of a DNA molecule. This portion forms a unit that codes for at least one protein product. The protein product produces the physical manifestation of the gene, such as colour, pattern, blood type, etc.

A gene is made up of introns and exons. Exons are coding regions, and introns are non-coding regions.

Each gene has a fixed place (locus) in a chromosome. Genes come in pairs in snakes and most other vertebrates because chromosomes come in homologous pairs. One gene is in one chromosome of the homologous pair, and the second gene is in the other chromosome. Genes can appear in more than one version (see allele). The two genes in a gene pair can be identical (homozygous) or not identical (heterozygous).

Graphic: A gene that is made up of an intron between two exons.
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Image Genotype

The identity of the genes, particularly those in a cell nucleus. An organism's complete hereditary information. (See Phenotype)

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Image Haploid

A cell has a set of single chromosomes. The chromosomes cannot be arranged into pairs. Many bacteria and the sperm and eggs of multicellular organisms are haploid. Some adult multicellular organisms, like the male honeybee, are haploid.

In haploid cells, the variable n is the total number of chromosomes. For example, corn snake gametes have 18 chromosomes, making n = 18. (See Diploid.)

Graphic: A haploid sperm cell fertilizes a haploid egg cell to produce a diploid zygote.
cigoto = zygote
diploide = diploid
fecundacion = fertilization
haploide = haploid
homologos = homologous chromosomes
nucleo del espermatozoide = nucleus of the sperm
nucleo del ovulo = nucleus of the egg
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Image Hemipenis (plural: hemipenes)

The hemipenes are the paired male mating organs in lizards and snakes. The original belief was that the two hemipenes were pressed together when used, and each hemipenis was half a penis (hemi means half). Actually, only one hemipenis is used at a time. This allows the male to approach the female from either the left or right side, depending on how the female is positioned. Flounces and spines ornament the hemipenis and make it more difficult for the male and female to separate before mating ends. If the pairing is disturbed, the male's hemipenis may get stuck and cannot be retracted into his tail. Sometimes this corrects itself, but in captivity animals can be helped with a massage with a wet glove.

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Image Heterozygous (adjective)

The two genes in a gene pair are not the same; they are different. A gene pair may be made up of a dominant mutant gene and a normal gene, a codominant mutant gene and a normal gene, a recessive mutant gene and a normal gene, or two different mutant genes. (See homozygous, dominance relationships.)

A heterozygote is an organism that has a heterozygous gene pair.

Graphic: A pair of homologous chromosomes. Each chromosome contains a double helix molecule of DNA. Gene B and gene b form a heterozygous gene pair.
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Image Homozygous (adjective)

The two genes in a gene pair are the same. They may be two copies of the normal gene or two copies of a mutant gene. The mutant gene may be dominant, codominant, or recessive to the normal gene. (See heterozygous, dominance relationships.)

A homozygote is an organism that has a homozygous gene pair.

Graphic: A pair of homologous chromosomes. Each chromosome contains a double helix molecule of DNA. Gene a and gene a form a homozygous gene pair.
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Image Hypo

Hypo basically means 'less' or 'reduced'. It is often a prefix that modifies the rest of the word. (See hypomelanistic.)

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Image Hypomelanistic

Hypo- means 'less' or 'reduced' and melanistic refers to black or dark pigment. It means less black pigment than normal. The word may be used generically or as the name of a gene.

A hypomelanistic animal has less than the normal amount of black pigment. It may even lack almost all of the black pigment. In corn snakes, hypomelanistic is the name of a gene that reduces the amount of black pigment. That reduction also makes the corn snake's red/orange pigment look brighter.

Unrelated genes that reduce the amount of black pigment in corn snakes:
Hypomelanistic (slang: hypo). AKA hypo A.
Sunkissed. AKA hypo B. A sunkissed corn snake has large saddles, an unusual head pattern, and dark clear checkers on the belly.
Lava. AKA hypo C, transparent. These snakes have transparent borders around the saddles.
Ultra. AKA ultrahypomelanistic, hypo D. The ultra mutant gene and the amelanistic mutant gene are alleles.
Christmas.
Dilute.

Photo: Lava corn snake
[img]http://i372.photobucket.com/albums/oo165/specialcorns/woordenlijst%20genetica/lava88.jpg[/img

Photo: Sunkissed corn snake
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Photo: Hypomelanistic corn snake
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Image Intermediate (see Codominant)

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Image Jacobson's organ

The Jacobson's organ is a specialized scent detector. It is located in the nasal cavity in mammals and some reptiles. In snakes and lizards like the skinks and monitors, it has virtually become a new sense organ. During embryonic life, the paired Jacobson's organs separate from the nasal cavities and develop openings into the roof of the mouth.

A snake's tongue flicks out of the mouth and waves up and down. Tonguing picks up scent molecules from an object or out of the air. These molecules are transferred to the Jacobson's organs and smelled. That information is sent through the olfactory nerves to the brain, where the information is analyzed. If the scent comes from a sexually receptive female or a prey animal, the search is on. If the scent is from a predator, the snake becomes more alert. The scent may also produce a characteristic fright reaction, such as that of a rattlesnake to a king snake's scent. A disturbed snake is likely to tongue more rapidly than normal to get more information about its surroundings.

Graphic: A snake's head, showing the Jacobson's organ
A = eye
B = tear gland
C = nasal cavity with olfactory cell lining
D = internal nostril
E = external nostril
F = protruded tongue
G = retracted tongue
H = Jacobson's organ
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Image Lavender

The Lavender mutant gene changes a corn snake's colour towards purple or violet. Lavender corns have a pale gray to pink ground colour with large pink to dark pink saddles. The eyes are often ruby red, but that does not seem to be part of the true lavender phenotype because some lavenders do not have ruby eyes.

Photos: Lavender corn snakes
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Image Linkage

Two loci are linked when they are in the same chromosome. Two loci are independent when they are not in the same chromosome. A chromosome map is built up from a series of linked gene loci. Linkage is most obvious when two loci are close together in the same chromosome. This makes it difficult to assemble two homozygous mutant gene pairs together in the same organism. If two linked loci are far apart, they may seem independent until a chromosome map is assembled.

Two mutant genes are linked in the cis phase when their loci are linked and the two genes are in the same chromosome. Two mutant genes are linked in the trans phase when their loci are linked and the two genes are in different chromosomes.

Graphic: A pair of homologous chromosomes. Each chromosome contains a double helix molecule of DNA. The a and B genes in the orange chromosome are linked in cis phase.

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Image Locus (plural: loci)

Locus is the Latin word for 'place'. A locus is the place in a chromosome where a particular gene or set of alleles is found. The two genes in a gene pair have the same locus.

Graphic: A pair of homologous chromosomes. Each chromosome contains a double helix molecule of DNA. The B and b genes have the same locus and are alleles. The B and a and P genes have different loci and are not alleles. Also see Linkage.

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Image Meiosis (see Cell division)

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Image Melanin

The black/brown colour pigment. Production of normal melanin requires a number of genes working together as a team.

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Image Melanine (see Melanin)

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Image Mitosis (see Cell division)

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Image Mutant

1. A living thing that does not have the wild type phenotype.

2. Any phenotype that differs from the wild type phenotype.

3. Any allele that is not the wild type allele. Therefore, any allele that is not the most common allele in the wild population. (See wild type.)

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Image Mutation

A mutation changes the order of bases in the DNA making up a gene. Mutations have many causes -- X-rays, toxic chemicals, etc.

A mutation produces a mutant gene. A mutant gene may produce a mutant phenotype.

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Image Normal

A synonym for wild type. See Wild type.

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Image Phenotype

Phenotype is derived from a Greek word meaning to appear. The phenotype is made up of all the observable properties of an organism. That includes the skin color, pattern, number of toes, blood type, and any other physical, psychological or behavioral manifestation. (See Genotype). The genotype and the envirmoment interact to produce the phenotype. Phenotypes are not inherited; only genotypes are inherited.

A phenotype may be reduced to the difference from the normal phenotype. For example, an amelanistic corn snake lacks black pigment but still has orange pigment, two eyes, a tongue, scales, and internal organs like a normal corn snake.

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Image Pheromones

Pheromones are scents which the female releases during mating season to attract males. The pheromone level is highest just after a shed. Like all scents, pheromone molecules are picked up by the tongue and transferred to the Jacobson's organ.

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Image Popping

Popping is a method to determine a snake's sex. The thumb puts pressure on the snake's tail to force the male's hemipenis forward and out through the vent. The snake is definitely a male only when the hemipenis becomes visible. No visible hemipenis means that the snake is either a female or a male that has tensed its tail muscles enough to prevent eversion.

Popping should only be done on hatchling snakes. It could injure an older snake.

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Image Probing

Other than egg laying, probing is the most accurate method to determine a snake's sex. A small blunt rod is sterilized (with alcohol) and lubricated with Vaseline or something similar. While holding the tail straight, the probe is carefully slid through the vent toward the tail. A probe is most likely to be successful if made a little to the right or left of the tail's centerline. The hemipenes are in the tail, and the probe slides into the pocket at the center of a retracted hemipenis. A probe goes further into a male's tail than into a female's tail (male = 4-8 scales, female = 1-2 scales).

Probing should only be done by an experienced person or under supervision of an experienced teacher. Probing incorrectly can puncture the hemipenis, which usually makes the snake unable to mate.

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Image Protoplasm

Protoplasm is made up of a cell's cytoplasm and nucleus. The term is seldom used in modern cell biology. (See Cell.)

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Image Recessive (see Dominance relationships)

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Image Wild type (= normal)

1. The most common phenotype in the wild population.

2. The most common allele at a gene locus in the wild population.

A mutant gene or phenotype is compared to the wild type standard. Using a standard minimizes the number of variables in a genetic experiment. A single variable means that the difference between the experimental result and the standard result was caused by that variable. When there are multiple variables, it can be difficult to tell how many variables there are, much less what each variable contributes to the final result.

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Image Xanthin

Yellow pigment. Production of normal xanthin requires a number of genes working together as a team.

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Image Xantine (see Xanthin)

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Image Zygote

A zygote is a fertilized egg. It is the diploid cell formed by the union of a haploid sperm cell and a haploid egg cell. After several cell divisions, a zygote becomes an embryo. Eventually a zygote becomes an adult which can produce its own sperm or eggs.

Graphic: A haploid sperm cell fertilizes a haploid egg cell to produce a diploid zygote.
cigoto = zygote
diploide = diploid
fecundacion = fertilization
haploide = haploid
homologos = homologous chromosomes
nucleo del espermatozoide = nucleus of the sperm
nucleo del ovulo = nucleus of the egg

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User avatar
eeji
Administrator
Posts: 9329
Joined: 25 Sep 2007, 21:12

Re: Explanation of genetic terms and words

by eeji » 14 Oct 2013, 19:55

great stuff, thank you! :cheers:


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