Dihybrid Crosses

What is a dihybrid criss?

• a genetic cross used to observe the inheritance of alleles and phenotypes for 2 genes

What is a dihybrid test cross?

• Same as a monohybrid test cross, the test cross is made with an individual which is homozygous recessive for both traits

What is a linked gene?

• Linked genes are genes located close together on the same chromosome, meaning they are more likely to be inherited together.

What are recombinants?

• Recombinants are chromosomes or gametes with new combinations of alleles that were created through genetic recombination, such as crossing over.

What are non-recombination?

• Non-recombinants are chromosomes or gametes that retain the original combinations of alleles found in the parental chromosomes.

• Same/similiar phenotypes to parents

Assuming the genes are not linked (independently assorted) (separate chromosomes), what would the ratio be?

1:1:1:1

What are unlinked genes?

• Unlinked genes are genes located on different chromosomes or far apart on the same chromosome, meaning they generally assort independently and are less likely to be inherited together.

What would the ratio be if the genes are linked?

1:(very very few):(very very few):1

How do you find out how many map units apart alleles are on chromosomes?

Find the % of recominates, and that is how many map units apart they are

What are monohybrid crosses?

• A monohybrid cross is a genetic cross that examines the inheritance of one characteristic (one gene) between two individuals.

On a monohybrid cross, how do you write a punnet square? (autosomal)

• For the mother 50% of her eggs would be B, 50% would be b, so you write B b

• For the father 50% of his sperm would be B, 50% would be b, so you write B b

On a monohybrid cross, how do you write a punnet square? (sex)

• Write the sex chromosomes, the the autosome as a superscript