Microbiology: Microbial Genetics Flashcards

Which type of RNA serves as the template for reverse transcriptase in retroviruses?

Answer: mRNA

Retroviruses carry single-stranded mRNA genomes that reverse transcriptase uses as a template to synthesize complementary DNA.

In bacterial conjugation, the F factor can integrate into the host chromosome, forming what type of cell?

Answer: Hfr cell

When the F factor integrates into the bacterial chromosome, it creates an Hfr (high-frequency recombination) cell capable of transferring chromosomal genes at elevated rates.

A frameshift mutation is most likely caused by which of the following?

Answer: Insertion of two nucleotides

Frameshift mutations result from insertions or deletions that are not multiples of three, shifting the reading frame; insertion of two nucleotides disrupts the triplet codons downstream.

Which enzyme is responsible for removing RNA primers during DNA replication in bacteria?

Answer: DNA polymerase I

DNA polymerase I removes RNA primers using its 5'→3' exonuclease activity and fills in the resulting gaps with DNA.

In Lederberg and Tatum's experiment demonstrating bacterial recombination, auxotrophic strains were used. What is an auxotroph?

Answer: An organism that requires an external supply of a specific nutrient

An auxotroph has lost the ability to synthesize a specific nutrient and must obtain it from the environment to grow.

The SOS response in bacteria is triggered by which of the following?

Answer: Accumulation of single-stranded DNA from replication blocks

Extensive DNA damage causes stalled replication forks and accumulation of single-stranded DNA, which activates RecA protein and induces the SOS repair response.

Which of the following best describes a missense mutation?

Answer: A codon changes to specify a different amino acid

A missense mutation causes a codon to specify a different amino acid, potentially altering protein function.