More Genetics

[SnowSnake]

Hello everyone,

I'm new to ssnakess, I hope we will get along fine! :)

I'm 15 and in sec. 4, i chose to take Sr. Biology and i like it a lot!!

Here is my question:

I learned about the punett square a few days ago and i was wondering if someone could make me a list of the corn snake genes and saying if they are Dominant, Co-Dominant or recessive.

Also, If Amelanistic and Anerythristic 'A' are recessive genes, What is the combinasion for a snow?(note: a=Anery 'A' and m=Amelanistic) I did the square and only got some aa,am,ma and mm. Can you tell me how the corn snake genetic punett square works please, I like genetics a lot! and would like to learn more about it.

ty for your help!,

SnowSnake

P.S. Sorry if genetics make your head hurt :D

[Pixie]

Hi SnowSnake :)

I can't answer you on the genetics question because it's still a big mystery to me! But, I wanted to say hello and it's nice to see you here :bounce:

Pixie

[Cas]

For a snow, starting with an anery (aaMM <--remember capital letters stand for the normal gene at that locus. The anery parent is normal at the amel locus) and an amel (AAmm) parent (P1), you end up with all snakes that are all normal looking but carrying amel and anery (so they're AaMm).
<table border="1" bgcolor="white" cellpadding="5">
<tr><td><br></td><td bgcolor="yellow">aM</td></tr>
<tr><td bgcolor="yellow">Am</td><td>AaMm</td></tr>
</table>

Breed the F1's together, (AaMm x AaMm) and the punnet's square looks like:<table border="1" bgcolor="white" cellpadding="5">
<tr><td><br></td><td bgcolor="yellow">AM</td><td bgcolor="yellow">Am</td><td bgcolor="yellow">aM</td><td bgcolor="yellow">am</td></tr>
<tr><td bgcolor="yellow">AM</td><td>AAMM</td><td>AAMm</td><td>AaMM</td><td>AaMm</td></tr>
<tr><td bgcolor="yellow">aM</td><td>aAMM</td><td>aAMm</td><td><font color="blue">aaMM</td><td><font color="blue">aaMm</td></tr>
<tr><td bgcolor="yellow">Am</td><td>AAmM</td><td><font color="red">AAmm</td><td>AamM</td><td><font color="red">Aamm</td></tr>
<tr><td bgcolor="yellow">am</td><td>aAmM</td><td><font color="red">aAmm</td><td><font color="blue">aamM</td><td><font color="green">aamm</td></tr>
</table>

green letters = snows, blue letters = anerys, red lettters = amels


As far as the genes go, there are (as far as I know), no dominant genes besides normal, and codominant is limited pretty much to motley/stripe. Some recessives are masked by others(eg: it's hard to tell if a blizzard is hypo) but I'm not sure if there are any recessives that are dominant to other recessives.
There are websites out there with lists of morphs and what combo of genes makes what... one good one is Serpwidget's page: http://www.serpwidgets.com/cornsnakes/Morphs/morphs.html

Dawn

[Cas]

Oh, also, try vmsherp's page with a basic explination of terms like amelanism and axanthism http://www.vmsherp.com/LCReptileMutation.htm

Dawn

[SnowSnake]

You will see below that i copied your first message. i will write my messages and questions in [].

For a snow, starting with an anery (aaMM[why do you have 2 alleles here? and can you explain what the gamete a and M mean.] <--remember capital letters stand for the normal gene at that locus. The anery parent is normal at the amel locus[whats a locus? and what does that sentence mean?]) and an amel (AAmm) parent (P1), you end up with all snakes that are all normal looking but carrying amel and anery (so they're AaMm[can you explain that code plz]).


aM

Am AaMm

[above: why does each parent pass on only 1 allele and how do you chose which one they pass?]

Breed the F1's together, (AaMm x AaMm) and the punnet's square looks like:

AM Am aM am

AM AAMM AAMm AaMM AaMm

aM aAMM aAMm aaMM aaMm

Am AAmM AAmm AamM Aamm

am aAmM aAmm aamM aamm

[why do the parents here pass 4 alleles when in the first breeding the parents had only 1 allele???]

ty again,

SnowSnake

[Cas]

(I used your same code, where anery is 'a', and amel is 'm'. A is the gene that would normally be present where a goes in an anery, and M is the normal counterpart to amel.)

There are 2 alleles because for any recessive trait, you need two copies of it in an animal for it to be expressed (actually visible). So an anery snake would have aa at the locii (location of the gene on the chromosome) for anery. The normal wildtype corn would have an AA there, (A in this case is the unmutated, normal gene) and a recessive carrier animal would have Aa. However, at the location on the chromosome where the amel alleles could sit, it will have an MM <-- the normal type genes. This makes the anery animals genotype aaMM
An amel would have mm at the amel locii, and AA at the anery locii

(think of it like looking at all possible alleles in a cornsnake - you could write out that it's homozygous for normal at all other loci (eg, BB at butter, SS at striped, HH at hypo), but since both parents are homozygous normal, we know all babies will also be homozygous normal, so we don't need to look at these ones. The parents have different alleles from each other at the anery and amel loci, so we have to consider them both).

My 1st punnets for the cross of these 2 (anery and amel) is just in short form... the amel can will contribute an A or an A and an m or m <-- so it will always contribute only Am; it's the same with the anery, only the genes are a and M. So all offspring will be AaMm. So rather than writing out 4 aaMM across the top and 4 AAmm down the side, I only put one.

In the second square, the genes can recombine in 4 unique ways during gamete production, that is, into aM, Am, am, and AM.


If you've only just started taking genetics in your class, this will make a lot more sense later when they teach you about dihybrid crosses (I'm really not a very good teacher ;) )

Dawn

[SnowSnake]

Hi cas,

I started genetics 2 days ago and i can already do dihybrid crosses thanks to you and http://www.serpwidgets.com/cornsnakes/default.html . I would say 99% of my class has problems with the small 4 square punett and i can already the dihybrids. LOLLLLL i cant wait to see the teachers face when i tell her that. omg that gonna be funny. I think that i will look for a job in the genetics domain, do you know any jobs that deal with genetics and punetts??

Thank you again!

SnowSnake

[Cas]

Your welcome, I rather enjoy genetics, and haven't had much reason to do much with it since my intro genetics class ended.

Genetics seems to be one of those things that some people just have to struggle to understand (I <i>hated</i> genetics in highschool, but it suddenly made sense when I took it in university... could just be I had a bad bio teacher in HS. But a lot of people even in university bio 110 had issues grasping the di- and trihybrid crosses).

As far as jobs, well, geneticist springs to mind ;) Most jobs that specifically deal with genetics are generally not quite so cut and dried as just solving punnets squares (or forked-line diagrams, which are much more useful in the tri and poly-hybrid crosses than punnets) however. It gets alot into dna structure, cloning (frequently bacterial cloning), and other things that are still interesting... but more complicated (and rather less interesting to me!).
And, of course, any kind of animal breeding deals with genetics... one reason corns are so much fun... you can play with their genetics, and if you raise feeders you can play with their genetics too.

Dawn

[SnowSnake]

Hi,

Can you show me an example of trihybrid crosses plz,


ty very much,

SnowSnake