UCR- BIO 106:Genetics Midterm #2

Why is knowing a gene's chromosomal position valuable for geneticists?

• They can determine recombination frequency.

• They can observe chiasmata formation.

• They can isolate and study gene function.

• They can examine crossing over between sister chromatids.

Why is the recombination frequency between two genes always under 50%?

• F1 gametes equally inherit alleles from both parents.

• A 50% frequency suggests the genes are unlinked.

• F1 gametes contain a 50/50 mix of parental and recombinant types.

• Chromosomes are limited to 50 map units in size.

What enables linkage map construction using recombination frequencies?

• Higher recombination suggests greater distance between genes.

• Lower recombination indicates greater gene distance.

• Frequencies correspond to physical distances in nanometers.

• Frequencies reveal gene sequences.

Which describes complete dominance?

• Homozygotes and heterozygotes have identical phenotypes.

• Both alleles are equally expressed in heterozygotes.

• Each wild type allele adds a fixed protein dose.

• Mutant alleles do not influence phenotype.

Under what condition does the 9:3:3:1 Mendelian ratio occur?

• Gene interaction exists, and mutations are on the same chromosome.

• No gene interaction and mutations are on different chromosomes.

• Gene interaction results in synthetic lethality.

• No gene interaction but synthetic lethality occurs.

What are the offspring phenotypes when two tailless Manx cats mate?

• 33% long tail, 66% tailless

• 100% long tail

• 50% long tail, 50% tailless

• 75% long tail, 25% tailless

Which Okazaki fragment would form when DNA is replicated left to right over this segment?

• 5′…ACCAGCACGTCAGACT…3′

• 5′…TCAGACTGCACGACCA…3′

• 5′…AGTCTGACGTGCTGGT…3′

• 5′…TGGTCGTGCAGTCTGA…3′

How did Watson and Crick determine base pairing using DNA’s width?

• Width suggests purines pair with pyrimidines.

• Only pyrimidine stacking causes grooves.

• Pyrimidine pairing produces a too-wide structure.

• Width determines 5' to 3' orientation.

Which feature allows RNA to form diverse 3D structures?

• A flexible double strand

• A flexible single strand

• Ribose sugar

• Uracil base

Which is not unique to RNA?

• Ribose

• Uracil

• Single-stranded

• Phosphate group