lecture 27 - prokaryotic cells Flashcards
What proportion of the earth’s biomass are made up of bacteria?
~50%
What are the 3 distinct types of shape possible for bacteria?
Cocci, rod, spiral
What is the structure of the bacterial chromosome?
bacteria have a single, circular chromosome of DNA
Do bacteria have a nuclear membrane?
No
How is the bacterial genome contained when there is no nuclear membrane?
It is restricted to the nucleoid
What are plasmids?
Small, circular, self-replicating DNA molecule found in the cytosol of a bacterial cell
What type of nucleic acid is in a plasmid?
Circular, double stranded DNA
What are bacterial cell walls made up of?
Peptidoglycan
What is peptidoglycan?
A rigid macro molecular layer that makes up the bacterial cell wall.
What is the function of the bacterial peptidoglycan cell wall?
Provides strength, prevents osmotic lysis/rupture, confers cell shape.
What is the structure of peptidoglycan?
Polysaccharide chains - alternating NAG and NAM - cross linked by peptides that have amino acid side chains (cross linking via transpeptidase)
What enzyme is involved in the peptide cross bridges between polysaccharide chains in peptidoglycan?
Transpeptidase
What is gram staining?
A laboratory staining process that will turn certain bacterial purple, and others pink
What type of bacteria will turn purple during gram staining?
Gram positive bacteria
Why type of bacteria will turn pink during gram staining?
Gram negative bacteria
What agent is initially used in gram staining to give the purple colour?
Crystal violet