Genetics

Question 1

What are the mechanisms by which linkage disequilibrium can occur?

Answer 1

physical linkage of genes (on same chromosome), on different chromosomes due to mutations, genetic drift, migration, selection pressure, and non-random mating

Question 2

How do you estimate the probability of two alleles occurring together? What is it called when the genes occur together at a lower frequency than expected?

Answer 2

multiply their occurrence rates; linkage disequilibrium refers to situations when alleles occur at rates greater or lesser than estimated from individual occurrence rates

Question 3

Why can’t the Hardy-Weinberg principal be used when assessing whether two alleles are in linkage equilibrium?

Answer 3

It does not apply when comparing allelic frequency from two distinct loci

Question 4

What is heteroplasmy?

Answer 4

the presence of different organellar genomes (e.g. mutated and wild type) within a single cell - often applied to explain differences in severity of mitochondrial diseases

Question 5

What is the law of segregation?

Answer 5

in gametogenesis, paired chromosomes are separated so that offspring inherit half of each parent’s DNA

Question 6

What’s it called when one mRNA encodes for multiple proteins? When does this occur?

Answer 6

polycistronic mRNA; while most prokaryotic mRNA is polycistronic, this is a rare property in eukaryotes

Question 7

What are 3 characteristics of most autosomal dominant diseases?

Answer 7

late onset, episodic, and variable expression