Microbiology Lecture Notes September 21

• E. Coli bacteria are killed by a virus
o Virus = T4 bacteriophage
 Infection of E. Coli q/ T4 bacteriophage
 E. Coli is gram (-)
 Gram negative bacteria picture
 Proteins allow things to go in/out of cell in cell wall and outer membrane as well as plasma membrane
• Allow transport of chemicals in/out of bacterial cell
 1st step: T4 bacteriophage adheres to a protein on the outer surface of the bacteria
• Ribosomes and Enzymes used for DNA replication
• Sticks to protein in the outer membrane of the E. Coli bacterium
 2nd Step: T4 bacteriophage through that interaction pokes a hole through all of the layers of the cell envelope of the E. Coli Bacterium
• Through that hole it injects its DNA
 3rd Step: The DNA belonging to the virus that kills the E. Coli is going to be copied by the enzymes and translated by bacterial ribosomes
• Gives a whole bunch of many copies of the T4 bacteriophage inside the bacterium
 4th Step: bacterial cells bursts because its full of the viral T4 bacteriophage
• Releases viruses out into the world

• E. Coli bacteria are killed by a virus
o Virus = T4 bacteriphage
o Questions – Can E. Coli become resistant to T4?
 Assuming they do become resistant to T4: why is it?
• Are they “immune” after virus attack & able to pass that acquired immunity on to offspring
• Is it just that some E. Coli are randomly “born” resistant to T4?
 If so, is it
• “acquired immunity”
• Bacterial communication/gene sharing
• All just random who lives and dies
• Adhesins:

Are ribosomes a good target for antibacterial drugs?
1. Bacterial adhesion to surfaces
a. “Adhesins” are usually integral or peripheral membrane proteins
i. Membrane/Cell Wall proteins used by bacteria to stick to surfaces
ii. More often they are peripheral membrane proteins
1. Peripheral Membrane proteins picture
2. Protein is in part of the membrane and does not go all the way through
b. Pili
i. Attachment to surfaces and motility
ii. Use on conjugation (bacterial sex) by some species
1. How they share plasmids with abx resistance
2. Pillus extension reaches over and sticks to another bacterium plasmid is copied and the copy of the plasmid is sent across the bridge to the other bacterium
2. Motility: flagella and pili
a. Pili
i. Example: adhesions on ends of pilli:
1. Are retractable extensions from bacterial cell envelope
b. Flagella (NOTe: bacterial flagella are NOT THE SAME as eukaryotic flagella)
i. Flagelar arrangements
1. Polar (ex. P aeruginosa)
2. Pertirchous (ex. E. Coli)
ii. Flagellin
iii. Basal body and hook
iv. Use of ATP
v. Similarity to secretion systems
vi. Similarity to ATP synthase of eukaryotic mitochondria
1. A brief digression on mitochondria and what bacteria do not have them

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