Dominant and Recessive

cobra759 · #1 (**permalink**) 17-05-2008, 09:03 PM

I'm trying to get my head round all the terms used when breeding snakes in order to get a particular colour/pattern etc.

From what I can figure out a dominant gene is one that will be displayed immediately in any offspring produced by the gene carrier, and a recessive gene is one that won't necessarily be displayed in any offspring but all offspring will carry the gene. So how do you bring a recessive gene to the fore?

No doubt I've got that wrong somewhere down the line,can anyone explain it in fairly simple terms,cos i'm a simple kind of man

AshMashMash · #2 (**permalink**) 17-05-2008, 09:05 PM

Haha, can i just copy my other post?

Quote:

Originally Posted by AshMashMash

A 'morph' is what we call a snake who's DNA is slightly different to a 'normal' ones. It has a mutation somewhere in the DNA, and is called a morph.

If the mutation produces phenotypic effects (ones that effect the snake some how), we can recognise it and breed these snakes to produce offspring similar to the parents.

Most mutations are recessive, and so you need two copies for the effect to show. Snakes that only have one copy of the mutated gene will look no different to a normal, but are called 'het', short for heterozygous. If two heterozygous animals breed, about 1/4 of the offspring will show the mutation, as they will be homozygous for it.

So, the common mutations ('morphs') in corns are things like amel, anery etc. Amel is short for amelanistic, the animal cannot make the gene converting tyrosine into melanin, so melanin (black) is NOT made, and the snake shows only red colouration.

Anery is short for anerythryistic, cannot make the red pigment, and shows up as the black/grey/white corns.

Ones that are double for both anery and amel will be more white, but still show some yellow.

Of course, there are LOADS of morphs in corns...

Have a google of 'punnet squares' and genes, and see also if that helps.

shaolinmaster · #3 (**permalink**) 17-05-2008, 09:10 PM

Check Out This Link:

New England Reptile Distributors, designer Ball Pythons, Reticulated Pythons, and much more!

Scroll Down To The Bottom and Follow The Links.

I Found It Very Informative and Quite Easy To Understand (But Remember We Are Talking About Genetics!)

shaolinmaster · #4 (**permalink**) 17-05-2008, 09:12 PM

Forgot to say Ash. I'm not really into Scorps......But Cool Picture On Your Sig!

AshMashMash · #5 (**permalink**) 17-05-2008, 09:13 PM

Quote:

Originally Posted by shaolinmaster

Forgot to say Ash. I'm not really into Scorps......But Cool Picture On Your Sig!

Haha, ta

I took the pic, but 'gothgirl' on here made the sig for me

Do you know what the quote means?

cobra759 · #6 (**permalink**) 17-05-2008, 09:31 PM

Cheers guys I'm getting there slowly with the genetics.

shaolinmaster · #7 (**permalink**) 17-05-2008, 09:37 PM

Am I correct Ash. Is it Pig Latin? From The Lion King?

See - Google IS Your Friend!!!!

tricky · #8 (**permalink**) 17-05-2008, 09:38 PM

im not !!!!!!!!! its all too much for me lol .

AshMashMash · #9 (**permalink**) 17-05-2008, 09:40 PM

Quote:

Originally Posted by shaolinmaster

Am I correct Ash. Is it Pig Latin? From The Lion King?

See - Google IS Your Friend!!!!

Hahaha, yes, it is

Do you know what it means though?

Ssthisto · #10 (**permalink**) 17-05-2008, 09:40 PM

Quote:

Originally Posted by cobra759

I'm trying to get my head round all the terms used when breeding snakes in order to get a particular colour/pattern etc.

From what I can figure out a dominant gene is one that will be displayed immediately in any offspring produced by the gene carrier, and a recessive gene is one that won't necessarily be displayed in any offspring but all offspring will carry the gene. So how do you bring a recessive gene to the fore?

No doubt I've got that wrong somewhere down the line,can anyone explain it in fairly simple terms,cos i'm a simple kind of man

Ok.

A dominant gene means that having no copies = does not show the gene.
Having one copy (het) OR having two copies (homozygous) looks exactly the same - and shows the gene. For example, "Spider" in royal python appears to be dominant - you can't tell if you have a het spider with one copy or a homozygous spider with two copies of the Spider gene - but if it doesn't LOOK like a spider, it doesn't carry the gene at all.

So you can actually breed a one-copy het spider (who also has one copy of normal "not spider") to a normal and get normal offspring - because the one-copy spider will only pass on spider half of the time on average.

Recessive genes mean that you have to have two copies to SHOW the gene - and that one or no copies looks the same.
An animal has to inherit one copy of the recessive gene from BOTH parents in order to show the trait. For example, "Albino" in royal pythons is a recessive trait. If you have a two-copy animal, it looks like an albino. An animal with one copy (het) looks normal (exactly the same as no-copies) - but if you breed it to another albino carrier or albino, you can get albino offspring.

And Codominant genes have three distinct appearances - having one copy looks different to having no copies or having two copies. For example, the "Pastel" gene in royal pythons is codominant. An animal with no copies of the gene is a normal royal. An animal with one copy (het) is a Pastel and has a distinctive look. An animal with two copies is a Super Pastel and has its own distinctive look, and can be distinguished from a single-copy Pastel.

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