# Panda's Question Thread -- "I know not the answers."



## Pandapop (Jul 27, 2012)

So while browsing the forums, I came upon a topic about the tan gene in mice.

What I gathered was, at/at is homozygous tan, and the mouse's babies will always be tan? But what if the paired mouse is a/a? Is it because the at/at mouse's genes are dominant over the a/a mouse, that regardless if one parent is not tan, the babies will still always be tan with that pair?

And the babies between an at/at and a/a mouse will be a/at, right? They'd be capable of passing tan or non-tan offspring?

Also, another question --

If a mouse is pied, what is the gene called? I know pied is dominant and does not need two copies to make pied offspring... so that means the babies between a pied mouse and a solid mouse have to be either pied or solid, right? A solid baby from a pied+non-pied pairing can't carry pied? This also applies to brindles, doesn't it? American brindles, not UK.

EDIT:

I think I found the answer to the pied bit.

Is it s/s that's a pied mouse, or S/S?
S/s is a mouse that carries pied, but doesn't show it, correct? So it's similar to the whole tan gene, thing...?
What happens if a mouse that is pied carries two copies of the gene? Is that possible? If so, will the babies always be pied, like the at/at mouse's babies will always be tan?


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## Serena (Dec 29, 2011)

you are right. Tan is a dominant Gene. So a mouse can have only one copy of it and still show the tan belly. That would be your a/at mouse. 
if you cross at/at with a/a all of the offspring will be a/at and therefore tan.
Those mice can either pass on the at or the a gene to their offspring. depending on that and the other parent, the babies can be tan or non-tan.
if you cross an a/at mouse with a/a you have a 50% chance of tan offspring.

piebald is a recessive gene. You need two copies to get a marked mouse. That's s/s in the genecode. 
since it's a recessive gene, mice can look solid, but have one copy of the gene (S/s) and pass it to their offspring. that's why you can get marked babies our of two self parents.
the only dominant spotting gene I know is variegated, but it looks different from piebald.


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## Fantasia Mousery (Jul 16, 2011)

I just have one correction. As you always put the dominant gene first, you write at/a and not a/at.


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## Serena (Dec 29, 2011)

as long as that's the only criticism, I can absolutely live with it


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