lecture 21 - linked genes & recombination

• How do linked genes affect the outcome of genetic crosses?

  Linked genes can result in offspring ratios that differ from those expected with independent assortment.
• What are the possible genotypes of the parents if two people with normal color vision have a son with color blindness?

  The genotypes of the parents are XNXn and XNY.
• What is the recombination frequency formula?

  Recombination frequency = (Number of recombinant offspring / Total offspring) × 100

  
• What does a recombination frequency of 17% indicate in terms of map units?

  It indicates a distance of 17 map units between the genes.

  
• What does it mean if genes are physically linked?

  It means that the genes are located on the same chromosome and tend to be inherited together.
• What does it mean for a gene to be “expressed”?

  • A gene is expressed when it is transcribed and translated into a functional protein.
• Crossover during Meiosis 1 can lead to a recombinant chromosome.
• Recombinant Chromosome


  A chromosome that has an allele combination that is not present in the parent
• What explains the proportion of "recombinant" progeny? 


  The distance between genes determines the recombination frequency.
• Recombinants happening at a lower frequency means they are likely closer together on the chromosome.
• Recombinants happening at a higher frequency means they are likely further apart on the chromosome.