exam question

Question 2

Explain why crossing over between two different genes, located on a pair of homologous chromosomes, results in a maximum of 50% of gametes with the recombinant alleles.

Answer 2

-crossing over occurs between the 2 chromosomes in the same homologous pair
-so after anaphase II half the chromosomes will be recombinant chromosomes, therefore 50% of gametes will have recombinant alleles
-crossing over doesn’t always take place so it may be that less than 50% of gametes have recombinant alleles

Question 3

Explain how meiosis results in genetic variation in the gametes

Answer 3

-meiosis results in recombination of alleles
-due to crossing over, which is when genes are swapped between chromosome in the same homologous pair
-and due to independent assortment, when it is completely random which side of the equator the chromosomes in a homologous pair end up