Genetics... a quick explanation

[jhall1468]

This is pretty basic stuff, but I needed to give a quick explanation to a friend that was confused (why Spiders are dominant and Pastels aren't) so I figured I'd post my explanation.

A side note:
* Genes come in "pairs", called alleles, they get one from both parent. When we talk about "hets" we are speaking of animals where one gene is "normal" and the other is mutated. Whereas, in homozygous animals, both genes are mutated.

* So it logically follows that breeding a homozygous ball python to any other ball python will produce 100% heterozygous offspring for that animal.

Simple Recessive

Heterozygous - The animal carries the gene, but has no visible mutation (it appears normal). Example: het Albino, het Piebald.

Homozygous - The animal carries the gene, and appears as a visible mutation. Example: Albino, Piebald.

Recessive traits require that both genes be mutated for the mutation to be visible. This is where the term "het" is typically used.

Codominant

Heterozygous - The animal carries the gene, and appears as a visible mutation. Example: Pastel, Woma.

Homozygous - The animal carries the gene, and appears as a visible mutation that is distinctly different from its heterozygous form. Example: Super Pastel, Super Woma.

It is important to note, the "Super" versions of codominant genes are not true dominant genes, which will be explained below.

Dominant

Heterozygous - The animal carries the gene, and appears as a visible mutation. Example: Spider.

Homozygous - The animal carries the gene, and appears as a visible mutation with no visible differences in comparison to its heterozygous form. Example: Spider.

True dominant genes will always appear the same, whether it's heterozygous or homozygous.

Pastels have brighter colors and blushing, Super Pastels have the same, just more of it. The reason why is simple: Pastels exhibit both the "Pastel" gene and the "Non-Pastel" gene, which diludes the mutation. So a "Pastel" could also be called a "het Super Pastel".

If I made a mistake anyone, please let me know .

[Shaun J]

Pastels have brighter colors and blushing, Super Pastels have the same, just more of it. The reason why is simple: Pastels exhibit both the "Pastel" gene and the "Non-Pastel" gene, which diludes the mutation. So a "Super Pastel" could also be called a "het Pastel".

If I made a mistake anyone, please let me know .

that part confused me a bit. Super pastels are the Homozygous form of the pastel morph, so how would a super pastel be a het pastel lol?

[jhall1468]

So it logically follows that breeding a homozygous ball python to any other ball python will produce 100% heterozygous offspring for that animal.

It's probably important to note, that mutations must occur on different gene pairs (alleles). So if you breed a homozygous mutated ball, to another mutated ball, and the alleles for the mutations are the same, it will likely result in bending space-time... or the slightly more likely fact, you won't get any babies (that are alive anyway).

[jhall1468]

that part confused me a bit. Super pastels are the Homozygous form of the pastel morph, so how would a super pastel be a het pastel lol?

Dangit... I read it twice too... lemme fix it.

[Shaun J]

much better... lol!

[titus]

It's probably important to note, that mutations must occur on different gene pairs (alleles). So if you breed a homozygous mutated ball, to another mutated ball, and the alleles for the mutations are the same, it will likely result in bending space-time... or the slightly more likely fact, you won't get any babies (that are alive anyway).

One corretion Genes/alleles occur in a locus and can be shared by other alleles that are are co-com ie. Montly and stripe corns the montly allele (gene pair) shares the same locus as the stripe allele. This makes it possible for a snake to be het for both Montly and stripe though, the montly gene is Dom to stripe thus the snake will look like a montly.

the Pastel gene has it's own locus but the gene is co-dom to normal thus showing a partial effect on the snake.

[jhall1468]

One corretion Genes/alleles occur in a locus and can be shared by other alleles that are are co-com ie. Montly and stripe corns the montly allele (gene pair) shares the same locus as the stripe allele. This makes it possible for a snake to be het for both Montly and stripe though, the montly gene is Dom to stripe thus the snake will look like a montly.

the Pastel gene has it's own locus but the gene is co-dom to normal thus showing a partial effect on the snake.

The primary purpose was to give a quick introduction, and mostly to correct the highly INCORRECT information about dominant/codominant genetic mutations out there.

Has the Montly/Stripe thing been proven out (ie, breed out to produce both Montlys and Stripes but completely unable to produce homozygous Montlys and Stripes?)

[titus]

Montly and stripe have been proven to share a locus though hom Montlys would be produced from Montly het.stripe x Montly het.stripe pairrings it would be inpossible to say which are hom Montly and Montly het. stripe. There is some work that shows that Cube may actualy also share the same locus.

[jhall1468]

I reread it and now I see what your saying. Which is why I noted that the mutations must occur on different alleles, not different loci. While different alleles can share the same loci, mutations cannot share the same allele (ie if the same gene pair that mutated the look of the piebald, also mutated the look of the snow, the two would be incompatible).

[titus]

I reread it and now I see what your saying. Which is why I noted that the mutations must occur on different alleles, not different loci. While different alleles can share the same loci, mutations cannot share the same allele (ie if the same gene pair that mutated the look of the piebald, also mutated the look of the snow, the two would be incompatible).

I see what your saying but also the mistake. The Allele is the actual gene pair in a loci, they do not have to be matching genes to be an allele though in most cases are. Co-doms such as Pastels have non matching genes in their allele (ie if normal is AA and Super Pastel is PP then the allele for Pastel is AP.) Incombatible genes come up when both genes share a Loci but are both recessive. (ie two forms of Amel aa we'll call type one and bb is type b. When bred you would have a allele of ab both genes are recessive to normal and to each other so you end up with a normal).