Bacterial Cell Division and Reproduction

Study Notes

A bacterial genome includes all genetic information in a cell, plus plasmids, transposons, and phages.
Bacteria reproduce by binary fission, involving cell elongation, chromosome duplication, and separation of daughter cells.
Each daughter cell inherits a copy of the mother cell's chromosome.

DNA replication starts at the origin of replication (oriC) and terminates at the terC.
The process involves the separation of the original chromosome's two strands and replication through DNA polymerase III.
Errors during DNA replication can result in mutations, which are inherited by daughter cells.
Mutations can alter the amino acid coding sequence of a gene, affecting the polypeptide sequence of the encoded protein.
The redundancy in the genetic code means some mutations are silent.

Mutations within the 16S rRNA gene can be used to measure the difference between organisms that have diverged from a common ancestor.
The sequence of the core genome (shared genes) can be compared to identify mutations and measure differences between closely related organisms.

Horizontal gene transfer accounts for the amount of genetic diversity within bacteria above and beyond what occurs through mutation.
There are three main mechanisms of horizontal gene transfer: conjugation, transduction, and transformation.

Conjugation involves the transfer of plasmids, which are extra-chromosomal pieces of DNA.
Transduction involves the integration of bacteriophages (bacterial viruses) into the host cell chromosome, potentially carrying DNA from previous hosts.
Transformation involves the uptake of DNA from the environment by bacterial cells in a special state known as competent.

Mobile genetic elements include insertion sequences, transposons, and bacteriophages.
Transposons are DNA elements that can move within a genome or be carried from one genome to another, often carrying antibiotic resistance genes and virulence determinants.