# Confusion over corn snake genetics



## Toonami (Mar 18, 2008)

So i was looking on a corn snake calculator and put in the combination of butter x butter, and it gave me 100% butter, is this correct, i was under the impression i would get 25% amel, 25% caramel and 50% butter.

It has been a few years since i last bred snakes and could have my punnett square completely wrong but im not sure a butter x butter would give me all butter when the morph has 2 reccessive traits.

Thanks
Natalie


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## bothrops (Jan 7, 2007)

Both the traits (amel and caramel) that make up a butter are recessive.

This means that a butter has two copies of the amel gene and two copies of the caramel gene.

If you put a butter to a butter, both animals have two 'amel' alleles at the 'amel' locus (and no 'normal' copies of the gene) and also have two 'caramel' alleles at their 'caramel' locus (and therefore no copies of the 'normal' allele at that locus).


This means that both parents can only give 'amel' and 'caramel' genes to the babies and all offsrping will be butters.

:2thumb:


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## Toonami (Mar 18, 2008)

Okay, so both parents will pass over one from each locus? and as that is only amel and caramel all babies will get 2 amel and 2 caramel making them butters? is that right?

Thanks


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## bothrops (Jan 7, 2007)

In terms of a Punnett square...


Lets code the Amel locus with 'A'. 'A' represents a normal copy of the gene (one that produces melanin) and 'a' represents the mutated version (amelanism)

AA = normal
Aa = normal het amel
aa = amel

Lets code the caramel locus with 'C'. 'C' represents a normal copy of the gene and 'c' represents the mutated version (caramel)

CC = normal
Cc = normal het caramel
cc = caramel




A butter will be

aacc



aacc x aacc

Each parent will give one copy of each gene to each offspring. This means that each egg will be 'ac' and each sperm will be 'ac'.

As these are the only gametes possible, the Punnet is easy (and completely unnecessary!)


-----ac

ac---aacc


100% butters.





Incidently, your scenario of 25% of each would come in the following circumstance:

Butter x normal het caramel het amel

aacc x AaCc


Butter's possible gametes = ac
Normal het butters possible gametes = AC, Ac, aC, ac

Possible combinations of babies:


-----ac

AC---AaCc

Ac---Aacc

aC---aaCc

ac---aacc



As you can see this gives:

25% normal 100% het butter
25% amel 100% het caramel
25% caramel 100% het amel
25% butter




:2thumb:


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## bothrops (Jan 7, 2007)

Toonami said:


> Okay, so both parents will pass over one from each locus? and as that is only amel and caramel all babies will get 2 amel and 2 caramel making them butters? is that right?
> 
> Thanks


Exactly.

:2thumb:


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## Rach1 (May 18, 2010)

I clicked on this, read it and now feel really thick..
I have no idea at all what any of that meant.


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## bothrops (Jan 7, 2007)

Rach1 said:


> I clicked on this, read it and now feel really thick..
> I have no idea at all what any of that meant.



It's ok - I've got that covered!

Start here! :2thumb:


http://www.reptileforums.co.uk/forums/genetics/814850-genetics-101-a.html


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## vetdebbie (Jan 4, 2008)

Is it odd that i can do genetics in my head, but can't do punnett squares for sh*t? lol


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## paulh (Sep 19, 2007)

I don't think it's odd. I need pencil and paper to do a 2 locus Punnett square but can do up to a 3 locus tree in my head. Doing it in my head is faster.


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## bothrops (Jan 7, 2007)

I very rarely use them when I'm solving problems, but I use them for teaching basics.


They are simply a method to make sure that you cover all the possible combinations of all the possible gametes from each parent. Which is handy to visualise when learning the basics. They are also good for representing crosses rather than actually calculating them in practical terms.

Of course, they completely rely on the correct identification of all the possible gametes so are limited (Just like a calculator - you only get the right answer if you input the right question!)


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## eeji (Feb 22, 2006)

If you want to check your own punnett squares are calculated correctly there is a calculator for that too Punnett Square Calculator - Ians Vivarium

[/plug]


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## fjfenton (Jan 4, 2009)

Is this the same principle for snow corns? Would snow x snow = 100% snow?
Cheers


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## eeji (Feb 22, 2006)

fjfenton said:


> Is this the same principle for snow corns? Would snow x snow = 100% snow?
> Cheers


yes as both parents can only pass down amel and anery and no 'normal unmutated' versions of those genes.


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