BIO3310 – Chapter 9: Horizontal Gene Transfer, Evolution, and Classification

17 question-and-answer flashcards covering transformation, conjugation, transduction, mobile genetic elements, microbial evolution, endosymbiosis, and microbial taxonomy from BIO3310 Chapter 9 lecture notes.

What is bacterial transformation?

The process by which a bacterial cell imports free (extracellular) DNA fragments or plasmids from its surroundings.

During transformation, what type of genetic material do bacteria commonly take up?

DNA fragments and plasmids released from nearby dead cells.

Which form of horizontal gene transfer requires direct cell-to-cell contact?

Conjugation.

What tubular structure is produced by donor cells to initiate conjugation?

A conjugation (sex) pilus.

How is DNA moved from donor to recipient during conjugation?

The donor sends DNA through the conjugation pilus into the recipient cell.

What are bacteriophages?

Viruses that infect bacterial cells.

What happens in generalized transduction?

A phage capsid mistakenly packages a fragment of bacterial DNA instead of phage DNA, transferring it to another bacterium.

What characterizes specialized transduction?

A phage genome first integrates into a specific site in the host genome and later transfers adjacent bacterial genes when it excises.

What are transposable elements (transposons)?

Genes that can move ("jump") from one DNA location to another within a genome or between a chromosome and a plasmid.

What is transposition?

The process by which transposable elements move to new positions in DNA.

List three major mechanisms that drive microbial divergence (evolution).

Random mutation, natural selection, and reductive (degenerative) evolution.

What is reductive evolution?

The loss of traits or genes that are no longer beneficial, often because the host provides the needed functions.

Define endosymbiosis.

A mutualistic relationship in which a host and its internal symbiont depend on each other for normal growth and development.

In taxonomy, what is meant by classification?

Organizing living organisms into hierarchical groups (taxa).

What is phylogeny?

The study of the evolutionary history and relatedness among organisms.

What is nomenclature in biological taxonomy?

The standardized system for naming living organisms.

Clicker review: Which horizontal gene-transfer mechanism uniquely depends on a conjugation pilus?

Conjugation.