A Lesson in Basic Genetics

Thanks for the good run down

Very interesting, and well done. I absolutely hated this class in college.

Thank You

This was a good read. I will need to print and file for future for me.

:)

HOW DOES ALL THIS WORK?

Picture a pair of shoestrings. Lay them down side-by-side. Now picture them with colored balls stuck to each of them:

-o-o-o-o-o-o-o-o-

-o-o-o-o-o-o-o-o-

Each -o-o-o- strand represents the double helix DNA molecule in a single chromosome.

Each dot represents a single gene or allele.

The dot in one chromosome and the corresponding dot in the same location in the other chromosome represent a pair of genes/alleles located at a specific locus.

Each pair of genes has a different “job” in determining the look of an animal. It takes many different pairs of genes, each doing a specific job, just to determine the overall pattern and colors of a snake.

When two animals mate and create young, each parent contributes one chromosome (including its double helix DNA molecule) from each pair of chromosomes to the offspring. Therefore, one gene from each parental pair of genes creates a whole new set of pairs in the offspring. For instance, the red dots…one red dot from the mom and one red dot from the dad. Always. One yellow dot from the mom, and one yellow dot from the dad.

Spider and Pinstripe should not be considered dominate, since there is a super fom and that super fom is lethal. If it was as simple as dominate and we assume that the homozygous form looks the same, we would be able to prove out homozygous individuals by the production of 100% spider or pinstripe offspring. And by cornells defintion of co-dominate we can safely put them under this catagory by listing the co-dom as lethal homozygous. One last statement - If Spider was true dominant, it would block expression of any other gene related to pattern, but as we see with other traits being visually observed when combined with spider, we again can assume that it is co-dominate, a trait that effects the phenotype without masking other genes whos traits can also be expressed :-).

Very good post though for the majority of BP people!

Quote:

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Originally Posted by reptileexperts

Spider and Pinstripe should not be considered dominate, since there is a super fom and that super fom is lethal. If it was as simple as dominate and we assume that the homozygous form looks the same, we would be able to prove out homozygous individuals by the production of 100% spider or pinstripe offspring. And by cornells defintion of co-dominate we can safely put them under this catagory by listing the co-dom as lethal homozygous. One last statement - If Spider was true dominant, it would block expression of any other gene related to pattern, but as we see with other traits being visually observed when combined with spider, we again can assume that it is co-dominate, a trait that effects the phenotype without masking other genes whos traits can also be expressed :-).

Very good post though for the majority of BP people!

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what is your evidence to back up the claim that the spider and pinstripe mutations are not dominant? not only is there no super, but to my knowledge there is no proof that the homozygous expression of either gene yields anything less than viable offspring. it's only secondhand, but I have heard precisely the opposite. do you have any firsthand information to the contrary?

by your definition, the only possible way for a mutation to be classified as dominant would be if it precludes the expression of any other co-dominant morphs. champagnes have a tendency to swallow up other mutations and overwhelm patterns. are they dominant? genetic black backs and reduced/banded snakes often pass on their patterns but there's no way you would classify those types of animals as co-dominant (or incomplete dominant for that matter).

why chime in on this post, again meant to assist newcomers with a rudimentary understanding of ball python genetics, with erroneous information over four years after Judy was good enough to put it up?

Errorness? I'm not going to hound you with my background nor do I care to partake in an argument on the interweb :-) However, see the other thread that is going on in regard to dominant traits.

The fact that noone has a spider or pinstripe that is proven homozygous, is evidence of this. The case for dominance is the exclusion of any other gene present. Co-domance is just what it says - allowing expression of multiple mutations on differnt loci, and in rare cases the same loci, but when its on the same loci it's more leaned toward incomplete dominance where the super form is the actual meant expression of that gene (my example being pastel).

Where is the proof for it? The fact that NO ONE has produced a homozygous spider or pinstripe is the proof, or at least the presented evidence I offer. If somone had a homozygous it would be known as all of its young would contain the dominate gene (not trait) allowing for expression of the trait.

Quote:

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Originally Posted by reptileexperts

Errorness? I'm not going to hound you with my background nor do I care to partake in an argument on the interweb :-) However, see the other thread that is going on in regard to dominant traits.

The fact that noone has a spider or pinstripe that is proven homozygous, is evidence of this. The case for dominance is the exclusion of any other gene present. Co-domance is just what it says - allowing expression of multiple mutations on differnt loci, and in rare cases the same loci, but when its on the same loci it's more leaned toward incomplete dominance where the super form is the actual meant expression of that gene (my example being pastel).

Where is the proof for it? The fact that NO ONE has produced a homozygous spider or pinstripe is the proof, or at least the presented evidence I offer. If somone had a homozygous it would be known as all of its young would contain the dominate gene (not trait) allowing for expression of the trait.

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Dominant/codominant/recessive describe the relationship of genes at a single locus. Multiple loci gets into epistasis and gene interactions.

I've looked at the thread on dominant traits. Absence of evidence is not evidence of absence.

What is the biochemical data indicating that pastel is an incomplete dominant mutant gene and not a codominant mutant gene? Let's take that question to PM, though.

Thank you! This has been a tremendous help.

YOU ROCK OUT LOUD FOR THIS POST!!!!!!!!!!!!!!

I have a 10 yr old who's into science and loves the morphs we already have, and this helps me show her how it works, hell it helps me too...lol..

I love the part about the spiders also because of the "taboo" behind them.......I love talking to my local and virtual "herpetologist" community about the crazy things they come across....LOL......I see all of you/us as pioneers, and explores of our passion. Gene's are the key codes to life and the more we find out the more doors we open, into new understanding. Endless possibilities, and the thought of producing or "PROVING" out something cool for all the herp community to enjoy!