6.1.2(b) - inheritance, AUTOSOMAL LINKAGE

for this to occur:

genes can undergo independent assortmore at metaphase 1 of meiosis

genes are unlinked

genes located on diff chromosomes

9:3:3:1 - standard F1 cross when e.g. AaBb x AaBb

autosomal linkage

  • Genes found on the same chromosome are said to be linked.

  • Where genes are on the same autosome (not sex chromosomes) it is called autosomal linkage

  • Linked genes will NOT be inherited independently of each other (no independent assortment at metaphase I). 

  • In other words, any 2 genes (that you look at) will tend to be inherited together.

  • The human genome contains over 20,000 genes, but we only have 23 pairs of chromosomes, so a large number of genes are found on each chromosome.

  •  All the genes on one chromosome will be inherited together and form a linkage group.

  • The person is heterozygous so genotype AaBb

  • One chromosome = AB the other is ab

  • Alleles A and B will tend to be inherited together and a and b will tend to be inherited together.

  • Most gametes will therefore be AB or ab
    (The line underneath denotes linkage)

AB, ab are parental type gametes