How Do You Calculate Genotype and Phenotype Ratios in a Trihybrid Cross?

  • Thread starter Worthless
  • Start date
  • Tags
    Cross
In summary, to determine the genotypes and phenotypes for the cross of TTBbRr with TtbbRr, you can use the probability method. This involves calculating the ratio of outcomes with a particular phenotype or genotype to the total number of outcomes. For example, in a cross of Aa x Aa, AA would have a probability of 1/4, Aa would have a probability of 1/2, and aa would have a probability of 1/4. This method can be more efficient for crosses with a large number of genes.
  • #1
Worthless
3
0

Homework Statement



How would you figure out the genotypes and phneotypes if you Cross TTBbRr with TtbbRr?
Trihybrid cross


Homework Equations




Cross TTBbRr with TtbbRr




The Attempt at a Solution



I did the crossing, but i don't know how to do the genotypes nor the phenotype ratio
 
Physics news on Phys.org
  • #2
[tex]\frac{Number \left \left of \left \left outcomes \left \left with \left \left a \left \left particular \left \left phenotype/genotype}{Total \left \left number \left \left of \left \left outcomes}[/tex]
For example, if you performed Aa x Aa, then there are four possible outcomes, AA, Aa, aA and aa. These are all equally likely, and two are the same. So, for AA, it appears once as an outcome of four possible outcomes, thus you get 1/4. For, Aa (aA is the same), is appears twice out of four possible outcomes, thus 2/4, or 1/2. For aa, it appears once out of four possible outcomes, thus 1/4.
I think that's what you were looking for. For crosses where a large number of genes is being considered, punnett squares and writing out the possibilities can be tiresome; and just using probabilities is easier (although possibly more prone to error).
 

1. What is the purpose of crossing TTBbRr with TtbbRr?

The purpose of crossing TTBbRr with TtbbRr is to observe the inheritance patterns of different traits in the offspring. This can help to understand how genes are passed down from parents to offspring and how different traits are expressed.

2. What traits are being crossed in this experiment?

The traits being crossed in this experiment are the presence or absence of the dominant allele T and the recessive allele t, as well as the presence or absence of the dominant allele B and the recessive allele b.

3. How many possible genotypes can result from this cross?

This cross can result in 16 different possible genotypes. This is because there are 4 possible genotypes for each of the 4 alleles being crossed (TT, Tt, tt, and Tt), and 4 x 4 = 16.

4. What is the expected phenotypic ratio of the offspring?

The expected phenotypic ratio of the offspring is 9:3:3:1. This means that for every 16 offspring, 9 are expected to exhibit both dominant traits (TTBB or TtBB), 3 are expected to exhibit one dominant and one recessive trait (TTBb, TtBb, TTBb, or Ttbb), 3 are expected to exhibit the other dominant and recessive trait (TTbb, Ttbb, TtBb, or Ttbb), and 1 is expected to exhibit both recessive traits (ttbb).

5. How can the results of this cross be used in practical applications?

The results of this cross can be used in practical applications such as breeding programs in agriculture and animal husbandry. By understanding the inheritance patterns of different traits, breeders can selectively breed for desired traits in offspring. This can lead to the development of new varieties of crops or the improvement of certain characteristics in livestock. Additionally, this type of cross can also be used in medical research to study the inheritance of genetic disorders and diseases.

Similar threads

  • Biology and Chemistry Homework Help
Replies
6
Views
4K
  • Biology and Chemistry Homework Help
Replies
3
Views
1K
  • Biology and Chemistry Homework Help
Replies
1
Views
1K
  • Biology and Chemistry Homework Help
Replies
1
Views
2K
  • Biology and Chemistry Homework Help
Replies
1
Views
6K
  • Biology and Chemistry Homework Help
Replies
1
Views
2K
Replies
1
Views
3K
  • Biology and Chemistry Homework Help
Replies
1
Views
3K
  • Biology and Chemistry Homework Help
Replies
8
Views
3K
  • Biology and Chemistry Homework Help
Replies
1
Views
2K
Back
Top