Genetic Linkage and Recombination Flashcards
What is genetic linkage?
The tendency of genes close together on a chromosome to be inherited together.
What disrupts genetic linkage?
Recombination (crossing over) during meiosis.
What does a recombination frequency of 50% indicate?
Genes are either unlinked or far apart on the same chromosome.
How is linkage measured?
In centimorgans (cM), where 1 cM = 1% recombination frequency.
What is a linkage map?
A chart that shows the relative positions of genes on a chromosome.
What is the chromosomal basis of Mendel’s laws?
Genes are located on chromosomes, which segregate independently during meiosis.
What is a parental type in a dihybrid cross?
Offspring with the same genotype as the parents.
What are recombinant types?
Offspring with new combinations of alleles due to crossing over.
Give an example of linked genes.
Coat color and tail length in hypothetical animals if they are inherited together.
Why are recombination events random?
Crossing over occurs at random points along chromosomes during meiosis.
How does linkage affect gamete formation in diseases like Usher syndrome and sickle cell anemia?
Linked genes on the same chromosome reduce recombination, favoring non-recombinant gametes.
How does recombination frequency influence offspring genotypes for linked genes?
Lower recombination between linked genes alters offspring ratios, increasing non-recombinant genotypes.
How does recombination affect genetic linkage?
Recombination breaks the linkage between genes by exchanging DNA between homologous chromosomes.
What is the molecular basis of crossing over?
Homologous chromosomes exchange genetic material at chiasmata during prophase I.
What is linkage disequilibrium?
A non-random association of alleles at two or more loci, often due to physical proximity on a chromosome.
