Skill:
• Identification of recombinants in crosses involving two linked genes
Recombinants of linked genes are those combinations of genes not found in the parents
- Recombinants occur as a result of crossing over of genetic material during prophase I of meiosis
- If linked genes become separated by a chiasma, there will be an exchange of alleles between the non-sister chromatids
- This creates new allele combinations that are different to those of the parent
Identifying Recombinants from Genotype
The frequency of recombinant phenotypes within a population will typically be lower than that of non-recombinant phenotypes
- This is because crossing over is a random process and chiasmata do not form at the same locations with every meiotic division
The relative frequency of recombinant phenotypes will be dependent on the distance between linked genes
- Recombination frequency between two linked genes will be greater when the genes are further apart on the chromosome
- This is because there are more possible locations where a chiasma could form between the genes
Recombinant phenotypes can be identified by performing a test cross (crossing with a homozygous recessive for both traits)
Identifying Recombinants from Phenotype
