Online A level Biology Tutor

View Original

Autosomal linkage - Try with 3 Alleles ...- Genetics and A-level Biology

Students find autosomal linkage a challenge ... I suspect this is because they mentally disconnect Meiosis from gamete formation.

Remember that the gametes in dihybrid inheritance result from the  independent assortment of the chromosomes in metaphase I. Consequently, if alleles are on the SAME chromosome then they cannot assort independently and must be passed to the gamete together (linked)... unless they form chiasma in Prophase one and exchange parts of the maternal and paternal chromosome (crossing over).

Here is a pdf of the question and a markscheme