Double Codominant x Normal = 25% Double Codominant? HELP!

[ReptileJenna]

Okay, I'm usually pretty good at genetics, but I'm stumped on this one.

Okay, so how in the world does the punnett square work in this type of situation. I'm using a bumblebee x normal scenario. Okay, so how do I set that up? What do I put for the Bumble bee? Do I put N p* N s* on top and then N N on the side? And when I do, I don't end up with the right results that would give me 25% chance for a bumblebee offspring.\

I might just be really tired, but either way, I refuse to sleep until I know, ha ha

Thanks for any help.

[OhhWatALoser]

List every gene combination each parent can give, the bumblebee can do 4, pastel and spider, pastel, spider, and normal. The normal can only give normal. I do it so capital letters = morph gene and smaller letters = non-morph gene.

	PS	Ps	pS	ps
ps	PpSs	Ppss	ppSs	ppss

and feel free to check yourself

Male:	Bumblebee
Female:	Normal
Percent	Fraction	Traits
25%	1/4	Bumblebee
25%	1/4	Pastel
25%	1/4	Spider
25%	1/4	Normal
View Results Page

[ReptileJenna]

Ah, I don't get it.

There are so many P's and S's! Okay, so a bumble bee is a pastel x spider, so it would give off one spider, one pastel, one normal?

[reptileexperts]

It has the chance to give off those odds, each egg has a chance that it could be normal, spider, pastel, or bee. There are two genes that are both dominate so it only requires one copy of the gene to show. The bee can give either the pastel gene, spider gene, or normal in each case making 4 possible allelic combos. It only takes one copy to show the trait. So in the above chart - P = Pastel, p = normal, S = Spider, s = Normal.

Therefor

PS = Bee
Ps = Pastel
pS = Spider
ps = Normal

Each egg has the same probability of hitting normal as it does bee, or pastel, or spider. It does NOT mean that you will get 1/4 each in every case. I know a breeder who bred bee to a norm and got all bees out of 5 eggs. It just has to do with chance since the genes are randomly combined and selected.

Make better sense?

[OhhWatALoser]

Ah, I don't get it.

There are so many P's and S's! Okay, so a bumble bee is a pastel x spider, so it would give off one spider, one pastel, one normal?

genes comes in pairs of two, each parent gives one gene from each pair of genes to the offspring. the normal parent can only give normal genes (ppss), no morph genes. the bumblebee (PpSs) can give pastel and spider, pastel, spider, or normal. The capital letters represent morph genes. lower case are just normal genes. you need two paired genes to make a baby.

PpSs is a big P and a big S so it is a pastel spider aka bumblebee
Ppss is just a big P so its pastel
ppSs is just a big S so its a spider
ppss has no big letters, so it's a normal.

[paulh]

genes comes in pairs of two, each parent gives one gene from each pair of genes to the offspring. the normal parent can only give normal genes (ppss), no morph genes. the bumblebee (PpSs) can give pastel and spider, pastel, spider, or normal. The capital letters represent morph genes. lower case are just normal genes. you need two paired genes to make a baby.

PpSs is a big P and a big S so it is a pastel spider aka bumblebee
Ppss is just a big P so its pastel
ppSs is just a big S so its a spider
ppss has no big letters, so it's a normal.

The normal genes are just as important in a breeding problem as the mutant genes.

A bumblebee x normal mating has two gene pairs of interest.

Bumblebee python gene pair #1: a pastel gene and a normal gene

Bumblebee python gene pair #2: a spider gene and a normal gene

Normal python gene pair #1: two normal genes

Normal python gene pair #2: two normal genes

Each sperm or egg gets one gene from each gene pair.

The bumblebee's sperm (or eggs) get either a pastel gene or a normal gene from gene pair #1. The bumblebee's sperm (or eggs) also get either a spider gene or a normal gene from gene pair #2. That gives four possibilities --
1. a pastel gene from gene pair #1 and a spider gene from gene pair #2 (P S)
2. a pastel gene from gene pair #1 and a normal gene from gene pair #2 (P s)
3. a normal gene from gene pair #1 and a spider gene from gene pair #2 (p S)
4. a normal gene from gene pair #1 and a normal gene from gene pair #2 (p s)

The normal snake's eggs (or sperm) can only get a normal gene from gene pair #1. The eggs (or sperm) can also get only a normal gene from gene pair #2. That gives only one possibility --
1. a normal gene from gene pair #1 and a normal gene from gene pair #2 (p s)

Those genes give you the 4 x 1 Punnett square shown in one of the earlier posts in this thread.

[RandyRemington]

It might help to name the two different normal genes as "normal for pastel" and "normal for spider".

Once you understand this combo you can really blow your mind thinking about a breeding of a combo of mutant alleles (two different mutations of the same gene).