Unit 5.4 (part 2) - AP Biology

Alterations of chromosome structure

Alterations of chromosome structure

• chromosome breakage can lead to 4 types of changes in chromosome structure: deletion, duplication, inversion, and translocation

Recombination of genes

• genetic recombination is the production of offspring w/ combinations of traits differing from either parent

  • offspring w/ phenotype matching one of the parent phenotypes are called parental types

  • Offspring e/ no parental phenotypes (new combinations of traits) are called recombinants

Gene linkage

• linked genes located very close together on the same chromosome tend to be inherited together

  • ex. Body color and wing size in fruit flies

• Linked genes that lead to ratios of offspring that are NOT what we’d predict w/ Punnet square

The farther apart two genes are, the higher the probability that a crossover will occur between them and therefore the high the recombination frequency

Mapping the distance between genes

• a linkage mal is genetic map of chromosome based on recombination frequencies

• Distances between genes can be expressed as map units

  • 1 map unit represents 1% recombination frequency