BIOL-2420 Unit 3A Review

This set of flashcards covers key concepts regarding DNA mutations, gene transfer mechanisms in prokaryotes, and gene regulation.

What defines a mutation?

A heritable change in DNA sequence.

What are the types of point mutations?

Missense, nonsense, and silent mutations.

What is a missense mutation?

A mutation that results in the addition of a different amino acid in a protein.

What is a nonsense mutation?

A mutation that creates a stop codon, leading to shorter, non-functional proteins.

What are silent mutations?

Mutations that do not affect protein function, often due to the degeneracy of the genetic code.

What is horizontal gene transfer?

Gene transfer between species of the same generation in prokaryotes.

What is bacterial conjugation?

The transfer of DNA from a donor to a recipient cell through direct contact, usually involving a pilus.

What occurs during transduction?

A bacteriophage transfers DNA from one bacterium to another.

What is transformation in bacteria?

The process by which a competent bacterium takes up free DNA from its environment and incorporates it into its genome.

What is catabolite repression?

Regulation of transcription by both repressors and activators, leading to a bifasic growth pattern in the presence of glucose.

What is the role of operons in gene regulation?

Operons allow coordinated regulation of genes with related functions.

What distinguishes repressible from inducible operons?

Repressible operons are turned off by the product of the pathway, while inducible operons are activated by substrate presence.

Explain the significance of the trp operon.

The trp operon contains genes for tryptophan synthesis and is regulated based on tryptophan availability.

Explain the significance of the lac operon.

The lac operon is regulated by the presence of lactose and glucose, controlling the metabolism of lactose.

What are the products of the lac operon when lactose is present?

Enzymes that facilitate the use of lactose as an energy source.

What is a frameshift mutation?

A mutation caused by insertion or deletion of bases not in multiples of three, leading to nonfunctional proteins.

What is a conditional mutation?

A mutation that only shows its effects under certain environmental conditions.

What is the significance of beneficial mutations?

They can confer advantages such as increased resistance to diseases like HIV.