BIOG251 Chapter 8: Microbial Genetics

Covers DNA replication in prokaryotes, the basics of transcription and translation in prokaryotes, and horizontal/vertical gene transfer between bacteria.

Vertical gene transfer

Gene transfers from parent to offspring

Horizontal gene transfer

Transfer of DNA between two living organisms that did not come from the parent

Competent cells

Cells that can accept genetic material and integrate it into their chromosome

Operons

Systems of genes that function as a unit; are only found in bacteria and archaea

Transduction, Transformation, and Conjugation

The three types of horizontal gene transfer

Plasmids

Used for horizontal gene transfer

Chromosomal fragments

Must integrate into the bacterial chromosome in order to be replicated

F factor (fertility factor)

Allows the synthesis of a conjugate pious, recipient cell has a recognition site on its surface

F+ factor

Cell that has and donates a plasmid

F-

A cell that lacks a plasmid and receives genetic information

Transformation

A cell picks up a dead bacteria’s genetic bacteria and integrates it

R (resistant) plasmid

Plasmid that causes antibacterial resistance occurs and spreads to other bacteria

Conjugation

Genetic material travels from the F+ cell to the F- cell, requires a pilus

Transduction

A virus passes genetic material from one bacteria to another

Generalized transduction

Any bacteriophage that takes a host’s genetic material and passes it to another; can only occur between similar bacteria

Specialized transduction

A temperate phage that was in a lysogenic state passes a combination of viral and bacterial genetics to another bacterium

The Lac Operon

A set of genes that transport and metabolize lactose

Regulator

Can recognize and bind to the operator or the small molecule

Lac I

The regulator in the Lac Operon; can bind to the operator or allolactose

Allolactose

A small molecule that is only present when lactose is present

When the regulator and the operon bind…

Transcription does NOT occur

When the regulator and small molecule bind…

Transcription does occur

What sections overlap?

The operator and the promoter