Okay so in a punnett square, how do you calculate the F1 generation?

Question

I'm in biology right now and I'm SO desperate to get this done, so if anyone can help me you'd be my seriously new best friend. So.

"Pure green apples are crossed with pure red apples. What color apples will result if green apples are dominant?"

I made my little Punnett Square and figured that the parental cross would be CC x cc. I'm kind of working off of that though. Can someone tell me if I'm right or wrong? I think I can go from there . . . But then it continues.

"The resulting apples from the cross in #5 (the quoted problem above) are crossed with each other. What types of apples will result?"

That's the F1 generation . . . right? I'M SO CONFUSED!

Answer 1

It depends on which type of apples are recessive and which are dominant. But if you crossed that, then you would get: Cc for all the crosses. Please add some more information.

The F1 generation is the 1st generation of offspring obtained from an experimental cross of two organisms.

Answer 2

You seem to be on the right track here.

The pure green apples and the pure red ones are your parental (P) generation.

I'm not sure why you're using the letter "C" to designate the colors (I'll assume this is in your book), but usually you'd use the letter of the dominant trait, in this case "G" for green (and "g", the lower case of the same letter, would be red).  Maybe "C" is meant to stand for "color".

But using "C" so you don't get confused, your parental cross is indeed CC x cc.  So you would set up your Punnett square as:

___|_c_|_c_|

_C_|___|___|

_C_|___|___|

(NOTE:  it doesn't matter which parent goes across the top and which is on the side - just separate the letters so each is in a separate row or column for a monohybrid cross [only one trait is used].)

Then you combine the letters from the top and side for each section in the square.  This will give you the 4 possible combinations.  The results you get inside the sections (in this case, they'd all be the same) are your F1 generation (you're correct here again).

Your results here should all be Cc (the C from the side + the c from the top).  So to cross your F1 results (Cc x Cc), you could use another Punnett square:

___|_C_|_c_|

_C_|___|___|

_c_|___|___|

Your results here are your F2 generation, and this time they won't all be the same.  You should get 3 different combinations for the GENOTYPE.  Now to figure out the PHENOTYPE, take your results from the last Punnett square and figure out what each would look like.  Remember, as long as you have one allele (gene) that's dominant, the dominant color will be the one expressed.  So even though you have 3 genotypes, you'll only have 2 phenotypes.

This link will give you some practice problems where you can check your work online:  http://www.ksu.edu/biology/pob/genetics/...  It also gives you hints if you aren't sure how to work the problem.

Answer 3

the F1 generation is the first generation of your cross.....it may help to know that F stands for filial or son ( meaning offspring) in latin

Maybe try to chose letters that mean more like G for green ( dominant) and g for red

AS you have correctly said GG = green ( pure breeding  or homozygous dominant), Gg will be green ( if this is complete dominance and not co dominance/incomplete dominace) but heterozygous and gg will be red ( or homozygous recessive.... this is to differentiate from GG)

your first cross ( to get the F1 generation) is GG x gg

or as you wrote CC x cc

in this cross ALL F1 offpsring will be Gg or Cc....heterozygous BUT show the dominant character which is GREEN.

What people like to ask after this first initial cross is to see what happens when you cross two F1's together so it will be Gg xGg.......WHY? This cross will give you the classic 3:1 ratio eg

-----G---------g

G--GG-------Gg

g---Gg-------gg

So you will get 3 out of the 4 showing the dominant trait and 1 showing the recessive ( this can also be asked in percentages so 75% show the dominant trait and 25% show the recessive trait.

THis will be called the F2 generation as it is you SECOND generation cross of this particular trait.....Break down the questrion.....they like to ask the same question in lots of ways...get a study book and look for the question, you will see it over and over again...just worded differently.