The Bacterial cell

Question 1

What are drug (antibiotic) targets in bacteria?

Answer 1

Cell wall (PG, gram neg. OM)
Ribosomes (70S)

Question 2

What is the composition of the gram negative cell wall?

Answer 2

Capsule
OM
PG
Periplasm
IM

Question 3

What is the composition of gram positive cell wall?

Answer 3

Capsule
PG
Periplasm
IM

Question 4

Name components of inner membrane

Answer 4

Phospholipid bilayer
Membrane proteins

Question 5

Name functions of inner membrane

Answer 5

Permeability barrier
Transport solutes
Location of enzyme systems

Question 6

Name bacterial lipids

Answer 6

Phosphatidylglycerol
Diphosphatidylglycerol
Phosphatidylethanolamine

Question 7

Describe the periplasmic space

Answer 7

Aqueous
Densely packed with proteins
Sequesters potentially harmful enzymes

Question 8

What are the differences between G. neg and G. pos cell walls?

Answer 8

G. neg
- thin
G. pos
- thick
- - techoic aicds

Question 9

What does the cell wall prevent?

Answer 9

Prevents osmotic lysis

Question 10

What does the gram negative OM doe?

Answer 10

Anchor for adhesin proteins
Prevents bile salts, antibiotics and lysozymes

Question 11

Describe lipopolysaccharides (LPS)

Answer 11

Composed of O-antigen (variable chain of sugars)
Aids in immune evasion and forms selective permeability barrier

Question 12

True or false: Low stimulation to innate immune system when LPS is detected

Answer 12

False: Highly stimulatory to our innate immune system

Question 13

Explain PAMP

Answer 13

Molecule immune systems to see and react to pathogen
Overstimulation of immune system

Question 14

What is PAMP?

Answer 14

Pathogen-associated molecular pattern (PAMP)

Question 15

Explain endotoxin

Answer 15

Released via OM vesicles or cell lysis
Activator of macrophages, cytokines, inflammatory reponse

Question 16

What are porins?

Answer 16

Transmembrane proteins that form a H2O-filled pore
Passive diffusion

Question 17

What do lysozymes and antibiotics attack?

Answer 17

PG cell wall
Major target for antibiotics (Penicillin)

Question 18

What are the glycan (carbohydrates) of the PG made from?

Answer 18

N-acetylglucosamine + N-acetylmuramic acid

Question 19

How many amino acids constitute the PG peptide chain?

Answer 19

5 - tetrapeptide

Question 20

Explain the PG biosynthesis

Answer 20

NAM-NAG subunits are transported across membrane which are assembled and crosslinked

Question 21

What assembled the NAM-NAG chain?

Answer 21

Transglycosylase with glycosidic bonds

Question 22

What cross links peptide sidechains?

Answer 22

Transpeptidase enzyme

Question 23

What do Penicillin binding proteins do?

Answer 23

Catalyse transglycosylation and transpeptidation

Question 24

True or false: PBS are targets for alpha lactam antibiotics

Answer 24

False: targets for beta-lactam antibiotics

Question 25

Explain techoic acids

Answer 25

Found in g. positive Lysis and release into blood stream Rigidity

Question 26

Is a bacterial capsule a pathogenicity factor?

Answer 26

Yes because not all bacteria have capsule which aids in immune evasion

Question 27

How does the capsule aid in immune evasion?

Answer 27

Prevent phagocytosis

Question 28

Explain how the bacterial ribosome is a drug target

Answer 28

Antibiotics disrupt protein synthesis Tetracyclines bind to 30S synthesis Macrolides block exit tunnel of ribosome

Question 29

Explain mobile genetic elements

Answer 29

Carries genes (AMR)

Question 30

What is bacterial conjugation?

Answer 30

Process by which genetic material is transferred from one bacteria to another

Question 31

Explain narrow host range and broad host range plasmids

Answer 31

NHR: only replicate in certain species BHR: replicate in many species

Question 32

Explain bacterial metabolism

Answer 32

Bacterias can metabolise various sugars Ability to utiilise different sugars (lactose, sorbitol) Used for diagnostic purpose (MacConkey agar)

Question 33

What do proteases do?

Answer 33

Degrade proteins in ECM which contribute to bacterial virulence

Question 34

How are proteins secreted in bacteria?

Answer 34

SEC (general secretion) pathway - if g. positive then job done Translocation across g. neg IM