Lecture 5 — Microbial Genetics

The study of inheritable traits as expressed in an organism’s genome.

DNA → RNA → protein.

The process of copying information from DNA into RNA.

RNA polymerase.

The process of using mRNA instructions to build a protein.

The ribosome.

RNA provides a working copy of genetic instructions while DNA remains the stored copy.

An organism’s genetic makeup.

The observable characteristics produced by an organism’s genes and environment.

The set of rules that relates mRNA codons to amino acids.

A sequence of three nucleotides in mRNA.

$AUG$.

$5′ \rightarrow 3′$.

It has the same sequence except RNA uses U instead of T.

A group of genes regulated together under shared control.

An operon that is usually off and can be switched on.

An operon that is usually on and can be switched off.

Regulation in which a repressor protein reduces gene expression.

Regulation in which an activator protein increases gene expression.

Regulating genes involved in lactose use.

The repressor binds the operator and blocks transcription.

Lactose-derived allolactose binds the repressor, allowing transcription.

Regulating genes involved in tryptophan synthesis.

Tryptophan helps activate the repressor, reducing transcription.

A change in the nucleotide sequence of DNA.

A mutation that occurs naturally, often because of an error during DNA replication.

Approximately once per \(10^9\) nucleotides copied.

Mutations caused by external factors such as radiation or chemicals.

DNA segments that can move and insert themselves into different locations in a genome.

High-energy radiation such as X-rays and gamma rays can damage or break the DNA backbone.

It can cause adjacent thymine bases to form thymine dimers.

They distort DNA and can interfere with replication and transcription.

Rare beneficial mutations can provide advantages that natural selection acts on.

No. Most are harmful or have little effect; a small number can be advantageous.

The movement of genetic material between organisms rather than inheritance from parent to offspring.

The transfer of genetic information from parent to offspring.

The uptake of free DNA from the environment by a cell.

DNA transfer between bacterial cells through direct cell-to-cell contact.

The transfer of bacterial DNA from one cell to another by a bacteriophage.

A phage accidentally packages bacterial DNA, potentially transferring different regions of the bacterial genome.

A phage transfers specific bacterial genes near the site where its DNA was integrated.

A small, independently replicating DNA molecule, commonly found in bacteria.

It can introduce new traits, including traits that may improve survival or cause disease.