unit 1

Question 1

describe gram neg structure

Answer 1

PM, PG with no gly5, OM with porins made of Lipid A, KDO, Core, O antigen (LPS)

Question 2

gram staining. whats each colour?

Answer 2

positive - purple
negative - pink

Question 3

4 gram staining steps

Answer 3

1. crystal violet
2. iodine
3. alcohol
4. safranin

Question 4

mycolic acid is found where

Answer 4

arabinogalactan layer of acid fast bacteria

Question 5

autoclave conditions

Answer 5

121degrees, 15psi, 20 mins

Question 6

flagella biosynthesis genes

Answer 6

early: flhc and flh d make FlhD2C2, which recruits sigma 70 and RNA pol to make middle gene

middle: sigma F and FlgM (anti-sigma factor, gets excreted through T3SS once structures built), then sigmaF binds late gene promoter

Question 7

describe transformation, transduction, conjugation and transposition

Answer 7

transformation: DNA taken up from environment and incorportaed in genome

transduction: DNA from bacteriophage gets incorporated into genome or stays in own plasmid

conjugation: DNA enters via pilus cell-cell contact (usually F plasmid transfered)

transposition: DNA (transposon) cut from one location and move to another

Question 8

name an antibiotic resistance test that compares gradients

Answer 8

kirby bauer test

Question 9

purpose of clavulanic acid

Answer 9

synthetic b lactamase competitor. added to antibiotics so b lactam ring cant get chopped by b lactamase

Question 10

What’s SCC Mec?

Answer 10

large genetic element that has mecA gene, makes PBP2a and inhibits B lactam antibiotics

Question 11

what drug works on MRSA? how?

Answer 11

teixobactin: affects PG synthesis of gram +

Question 12

molecular koch postulates vs organismal

Answer 12

1. gene linked to disease in animal
2. removal of gene = loss or reduction of virulence
3. returing gene in organism restores full virulence

organismal:
1. agent absent in healthy and present in diseased.
2. agent isolated and grown in culture
3. causes disease when reintroduced in person
4. agent must be re-isolated

Question 13

give an example of an AB toxin and describe how it works

Answer 13

Diphtheria toxin - inhibits protein synthesis.

A subunit inactivates elongation factor 2 by transferring ADP-ribose on it. thus stops protein elongation, killing the cell

Question 14

shiga toxin is an example of an ab or ab5 toxin? what disease causes it?

Answer 14

ab5 caused by pathogenic E.coli (0157:h7)

Question 15

ab5 toxin example and mechanism

Answer 15

cholera toxin.

a1 cleaved after phag, adp-ribosilated G protein, acenylyl cyclase activated, cAMP increased, cell secretes fluit and salt

Question 16

pathogenicity islands have high ______ content

Answer 16

GC

Question 17

describe STEC infection process

Answer 17

pili attaches to host, activates T3SS, Tir inserts into host, acts as receptor for intimin, then actin-based pedestal formed, curli aids in biofilm formation, stec releases shiga toxins which binds Gb3, stx binds ribosome and stops protein synthesis

Question 18

the purpose of ____ secreting gbpA is ____

Answer 18

v.cholerae ; facilitate binding to chitin or small intestine

Question 19

cholera process

Answer 19

cholera binds to GbpA, uses TCP to make stronger attachment, forms biofilm, secretes toxin, B5 binds GM1, toxin taken into cell where activates adenyl cyclase and increases cAMP, water and salt secreted from cell, diarrhea

Question 20

listeria is a gram ___ bacteria

Answer 20

positive

Question 21

3 listeria monocytogenese virulence factors

Answer 21

1. internalin B: binds to met to internalize listeria
2. LLO (exotoxin) forms pore in vacuole when pH drops to let lysteria out
3. ActA - actin modulating protein that moves bacteria in cell

Question 22

staph aureus bacteria type

Answer 22

gram positive