#1

So I'm doing a tetrahybrid cross in biology where both parents are heterozygous for 4 traits, the traits being:

Dimpled chin dominant to non-dimpled chin

Brown eyes dominant to blue

Rollers dominant to non-rollers

Widows peak dominant to straight hair line

So the cross would be: DdBbRrWw x DdBbRrWw.

I need to know what the phenotypic ratio for this is, as I'm doing a poster where I have to do solve this with a punnet square and product rule, and list the genotypic ratio and phenotypic ratio for both. Does anyone know the number formula for this is, like for a dihybrid cross it would be 9-3-3-1?

Dimpled chin dominant to non-dimpled chin

Brown eyes dominant to blue

Rollers dominant to non-rollers

Widows peak dominant to straight hair line

So the cross would be: DdBbRrWw x DdBbRrWw.

I need to know what the phenotypic ratio for this is, as I'm doing a poster where I have to do solve this with a punnet square and product rule, and list the genotypic ratio and phenotypic ratio for both. Does anyone know the number formula for this is, like for a dihybrid cross it would be 9-3-3-1?

#2

Yes, it would.

#3

I think so

#4

Yes.

#5

#6

I should report your post as potentially dangerous. It isn't safe for pit monkeys to take in this kind of stuff, their heads might explode.

#7

Good lordy, Tetrahybrid?

If you don't know, just do a punnet square.

..I'm assuming you do know what a punnet square is.

EDIT: If you're making a poster, it might be a good idea to make that Punnet square, just to show your working, etc. But generally, I think, if it's a cross between two heterozygous parents, the phenotypic ratio should be 9:3:3:!

EDIT2: If you do a punnet sqaure, anyway, you can work out the phenotypic ratio!! Quit being lazy and get to work (That is kind of the point of punnet squares..)

If you don't know, just do a punnet square.

..I'm assuming you do know what a punnet square is.

EDIT: If you're making a poster, it might be a good idea to make that Punnet square, just to show your working, etc. But generally, I think, if it's a cross between two heterozygous parents, the phenotypic ratio should be 9:3:3:!

EDIT2: If you do a punnet sqaure, anyway, you can work out the phenotypic ratio!! Quit being lazy and get to work (That is kind of the point of punnet squares..)

*Last edited by dannyboy14 at Nov 19, 2008,*

#8

I don't think any of the above actually read the whole post.

Sorry i did all that last year and forgot it all

Sorry i did all that last year and forgot it all

#9

I already did the punnet square and found the GR, but now I need to find the PR, and I'm trying to find it without having to go through all the GR entries and possibly make a mistake.

#10

Am I the only one who saw the title of this thread and thought it was about marijuana?

#11

I already did the punnet square and found the GR, but now I need to find the PR, and I'm trying to find it without having to go through all the GR entries and possibly make a mistake.

Ok, I did this stuff in yr. 12 biology in Australia, so the course is slightly different to what you're doing. What do you mean by Product Rule?

#12

The product rule is when you take one trait's alleles from both parents, multiply them by a fraction of either 1/1 if its homozygous (AA, aa) or 1/2 if its heterozygous (Aa) So for a monohybrid with parents AA x AA, you multiply 1/1A x 1/1A and the gr is 1/1AA. It's difficult to explain, so sorry if it's still unclear to you. >.>

#13

boy oh boy am i glad that there are people that study this so i don't have to

#14

The product rule is when you take one trait's alleles from both parents, multiply them by a fraction of either 1/1 if its homozygous (AA, aa) or 1/2 if its heterozygous (Aa) So for a monohybrid with parents AA x AA, you multiply 1/1A x 1/1A and the gr is 1/1AA. It's difficult to explain, so sorry if it's still unclear to you. >.>

Ah sorry man, we didn't do that where I was. Probably the only way I can suggest is to just take the alleles from the punnet square and do you little multiplication above. (Just because I didn't ever do the product rule). Because the phenotypic ratio does not delve into being homozygous dominant/heterozygous, whereby the traits will appear the same, there probably isn't a sound way to base the product rule off the phenotypic ratio.. (That I know of, anyway).

Just make sure you record the total number of each allele, and make sure this checks out with your calculations.

Sorry I can't be more help.

#15

Good lordy, Tetrahybrid?

If you don't know, just do a punnet square.

..I'm assuming you do know what a punnet square is.

EDIT: If you're making a poster, it might be a good idea to make that Punnet square, just to show your working, etc. But generally, I think, if it's a cross between two heterozygous parents, the phenotypic ratio should be 9:3:3:!

EDIT2: If you do a punnet sqaure, anyway, you can work out the phenotypic ratio!! Quit being lazy and get to work (That is kind of the point of punnet squares..)

a punnet square for all heterozygous traits? that'd be ****ing hell

the best advice i can give ya is to find the ratios by multiplication. Assuming its complete dominance, know that for every trait, the dominant phenotype is 3/4 and the recessive phenotype is 1/4. so from there, just figure out the different possible phenotypes and multiply each traits chance

#16

Well thanks for the help guys, lol, but I found a source that said the ratio is 81-27-27-27-27-9-9-9-9-9-9-3-3-3-3-1, and it adds up to the total number of squares. so yay!

#17

Where is that one guy with the avatar and the sword and he is really giood art science when you need him?

#18

a punnet square for all heterozygous traits? that'd be ****ing hell

the best advice i can give ya is to find the ratios by multiplication. Assuming its complete dominance, know that for every trait, the dominant phenotype is 3/4 and the recessive phenotype is 1/4. so from there, just figure out the different possible phenotypes and multiply each traits chance

Hell is right. It took me 2 and a half hours filling in the punnet square. >.>

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