Genetics Exam 3 Practice Questions

Which of these is NOT a reason that mutations are important

• Mutations provide genetic stability

• Mutations can cause diseases and disorders

• Mutations are the raw material of evolution

• Mutations help researchers understand biological processes

T/F: In humans, somatic cell mutations are passed on to the progeny of the individual with the somatic cell mutation.

• True

• False

Which of the following types of gene mutation in a protein-coding gene usually have the least severe (i.e., deleterious) effect on the phenotype?

• base deletions

• nonsense substitutions

• missense substitutions

• expansion of a trinucleotide repeat

A mutation in gene X overrides the effect of a previous mutation in gene Y and restores the wild-type phenotype. The mutation in gene X is called a(n) ________ mutation

• reverse

• intragenic suppressor

• intergenic suppressor

• neutral

The kind of gene whose product interacts with other nucleotide sequences to affect their transcription or translation is a _______ gene.

• constitutive

• regulatory

• structural

• protein-coding

DNA-binding proteins interact _______ with DNA, usually via ________ bonds.

• dynamically / hydrogen

• dynamically / covalent

• permanently / hydrogen

• permanently / phosphodiester

For a(n) _______ operon, transcription normally takes place, and it is turned off by a(n) _______.

• inducible / activator

• inducible / repressor

• repressible / activator

• repressible / repressor

Low levels of glucose lead to all of these EXCEPT

• cAMP levels increase

• permease levels increase

• CAP-cAMP loses its affinity to DNA

• lac operon is activated

When tryptophan concentrations are high in an E. coli cell, what happens?

• Tryptophan binds the repressor and it can repress trp

• attenuation causes premature termination of transcription of the trp operon

• the tryptophan synthesis genes are not transcribed

• all of the above

Both miRNA and siRNA production include the chopping of double-stranded RNA molecules by the dicer enzyme. How long are these new, tiny strands that go on to combine with proteins to form the RISC comple?

• miRNA 7-11 nucleotides, siRNA 21-25 nucleotides

• miRNA 21-25 nucleotides, siRNA 7-11 nucleotides

• Both 21-25 nucleotides