# Tetrahybrid Cross

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dbzmaniac1000

11-19-2008, 08:26 PM

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?

heaven's gate

11-19-2008, 08:27 PM

Yes, it would.

DaveM666

11-19-2008, 08:32 PM

I think so

Xiaoxi

11-19-2008, 08:36 PM

Yes.

dbzmaniac1000

11-19-2008, 08:42 PM

:facepalm:

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.

dannyboy14

11-19-2008, 08:50 PM

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 :p: (That is kind of the point of punnet squares..)

haveaniceday233

11-19-2008, 08:53 PM

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

Sorry i did all that last year and forgot it all

dbzmaniac1000

11-19-2008, 08:56 PM

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.

kosmic

11-19-2008, 08:59 PM

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

:sad:

dannyboy14

11-19-2008, 09:00 PM

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?

dbzmaniac1000

11-19-2008, 09:06 PM

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. >.>

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

dannyboy14

11-19-2008, 09:14 PM

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.

cap'n curry

11-19-2008, 09:19 PM

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 :p: (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

dbzmaniac1000

11-19-2008, 09:20 PM

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!

tayroar

11-19-2008, 09:21 PM

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

dbzmaniac1000

11-19-2008, 09:26 PM

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. >.>

A8039077

11-19-2008, 09:26 PM

http://en.wikipedia.org/wiki/Wikipedia:Reference_desk/Archives/Science/2007_September_6#Mendelian_tetrahybrid_cross_ratio

That may help

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