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chrisman10

Di hybrid cross

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Does the f1 generation only occur when you have homozygous parents? Or can someone explain the concept of f1 and f2 generation?

 

What I know so far is that. Your giving to parents for e.g

 

p1 p2

 

Ww GG x ww gg < step 1

 

Gametes : WG WG wG wG wg wg wg wg Step 2

 

F1 ?... I'm confused here , what would be the f1 generation here..

 

What I do is simply do the following

 

Parent #1 can only give two gametes so which is ... WG wg and parent #2 can only give one which is wg.

 

Now I place them in the punnett square to get WG wg

 

wg WwGg wwgg

 

 

So did I do anything wrong? Like whats the f1 generation and f2 generation. I'm really confused because my book shows a two homozygous parents which go through f1 and f2 like

 

P1

Gamete

f1 Gen

f2 Gen

 

 

Thanks

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I am quite new to genetics as well so forgive me if I am wrong but you can cross heterozygous parents as well. Parent 1 would give you WG wG and parent 2 would give you wg haploid gametes. So when you plug those into the punnett square you should get 2 different diploid cells; this will be your f1 generation.

 

Now if you cross f1 X f1 you take each of those diploid genotypes and work them into 4 different haploid gametes once again. Put those in a second punnett square and you will get the f2 generation phenotypes. It is common to get a 9:3:3:1 ratio but that is if both parents are homozygous. It will be a fraction of 16 (?/16). Hope this helps.

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