Bacteria

3 common shapes of Prokaryotes

• Cocci (Spherical)

• Bacilli (Rod-shaped)

• Spirilla (Spiral)

Do bacteria have cell walls

yes, roughly 90% do

What is the benefit of a cell wall in prokaryotes

A cell wall provides structural support, maintains cell shape, and protects against osmotic pressure that could cause the cell to burst.

peptidoglycan

A strong mesh-like material made of sugars and amino acids that forms the bacterial cell wall, providing structural support

Two major categories of antibiotics act by inhibiting
peptidoglycan synthesis

• Beta lactam (β-lactam) antibiotics eg the penicillin

family

• Glycopeptide antibiotics eg vancomycin and others

What are Gram-positive bacteria?

Bacteria with a thick peptidoglycan cell wall that retain the crystal violet stain and appear purple under a microscope.

What are Gram-negative bacteria?

Bacteria with a thin peptidoglycan cell wall and an outer membrane that lose the crystal violet stain and appear pink/red after counterstaining.

What defines prokaryotes relative to eukaryotes?

Prokaryotes lack a membrane-bound nucleus and membrane-bound organelles; eukaryotes have them.

What is the form of bacterial DNA?

Usually a single, circular, double-stranded DNA chromosome located in the nucleoid region. Bacteria may also contain plasmids.

Are bacteria single-stranded or double-stranded?

Bacterial chromosomes are usually double-stranded (dsDNA).

Are bacteria diploid or haploid?

Bacteria are generally haploid, meaning they typically have one copy of their chromosome.

lysozyme

An enzyme that breaks down peptidoglycan in bacterial cell walls, weakening the wall and potentially causing the cell to burst.

How do bacteria divide?

Through binary fission, where one bacterial cell replicates its DNA and splits into two genetically similar daughter cells

Transformation

bacterium takes up free DNA from its immediate environment, and incorporates the new DNA into its genome, resulting in a change/transformation in its typical characteristics.

What is transduction?

Gene transfer between bacteria facilitated by bacteriophages (viruses that infect bacteria).

What is conjugation?

Gene transfer directly from one bacterium to another through cell-to-cell contact.