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Dihybrid Cross
Next Generation: HS.LS3.3 HS.LS3.3

Dihybrid Cross

Author: Nathan Lampson
Description:

Similar to a Punnet square, a dihybrid cross tracks genetic traits passed from parents. A dihybrid cross, however, tracks two traits, not just one. This tutorial demonstrates how to find all possible gametes, explains the role of alleles and introduces how to write ratios of the different phenotypes as a result of a dihybrid cross.  

 

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Tutorial

 

A Dihybrid Cross is a type of punnett square used to determine multiple genetic traits at once.

Two traits of two parents are visualized by a dihybrid cross punnett square.  A dihybrid cross is larger than a monohybrid cross because two traits are being visualized at the same time.

 

Genotypes are letters used to represent physical traits.

S is the genotype used to represent a cat with a short tail.

 

Phenotypes are physical traits.

A short tail is a phenotype.

 

Law of Independent Assortment

Traits are inherited independent of one another.  The inheritance of one trait does not effect the inheritance of another.

Cats that have short tails are equally likely to have brown fur or white fur.

 

In this example, a cat with a short tail and white fur is crossed with a long tailed and brown furred cat.  

Offspring possessing a dominate S allele will have a short tail.  Offspring possessing a dominant B allele will have brown fur.