Lecture 13

Question 1

How do bacteria invade human body

Answer 1

-Through mucus membranes (respiratory and garstrointestinal tracts, urinary tract and genital openings)
-Non intact skin (bites, wounds, injections…)

Question 2

How do bacterial pathogens damage host cells?

Answer 2

1. Invasion
2. Toxins

Question 3

What is invasion

Answer 3

Ability to spread to other loc in host by invading cells or tissues. Atp that signs of illness and disease occur

Question 4

what are Toxins

Answer 4

Very specific virulent factor produced by bacterial pathogens, poisonous substances to host

Question 5

What is toxigenicity

Answer 5

Organism’s ability to make toxins

Question 6

Two categories of toxins

Answer 6

Endotoxins and exotoxins

Question 7

Exotoxins

Answer 7

Toxin secreted by microorganism into surrounding enviro

Question 8

Endotoxin

Answer 8

Toxin release by microorganism into environment when it dies, it’s part of cell wall

Question 9

Impacts to metabolic pathways in eukaryote host by bacterial toxins

Answer 9

1. Damage cell membrane
2. Disrupt prot synthesis
3. Inhibiting function of nervous syst
4. Inhibiting activation of host immune syst

Question 10

Some pathogens

Answer 10

Gonorrhea, lyme disease, strep throat, tuberculosis, tetanus

Question 11

What are antibiotics

Answer 11

Drugs to treat infections caused by bacteria

Question 12

What is zone of inhibition (ZOI)

Answer 12

Clear zone surrounding antimicrobial agent, complete absence of bacteria

Question 13

What is a bacterial lawn

Answer 13

Dense and uniform layer of bacteria on agar plate

Question 14

What is selective toxicity

Answer 14

When agents affect pathogens and not host (by interacting with structures not present in/diff from host)

Question 15

Antibiotic modes of action

Answer 15

1. Cell wall synthesis
2. Cell membrane function
3. Metabolic reaction
4. Prot synthesis
5. Dna synthesis

Question 16

Inhibitors of cell wall synthesis (ex penicillin)

Answer 16

Targets cell wall(critical for survival of bacteria)

Question 17

Inhibitors of cell membrane function:

Answer 17

Content of cell will leak out and cell dies. However, often poorly selective and can be toxic for systemic use in mammalian host -> only topical

Question 18

Inhibitors of metabolic processes:

Answer 18

Inhibits certain pathways necessary for bacteria survival

Question 19

Inhibitor of prot synthesis

Answer 19

Target ribosome components (diff from eukaryotic) and leads to death bc prot synthesis is necessary for multiplication/survival of bacteria

Question 20

Inhibitors of nucleic acid synthesis

Answer 20

Binding to components involved in process of dna or rna -> hinders multiplication

Question 21

Cell wall function

Answer 21

Very strong, resists bursting/maintains shape, structural support and protection

Question 22

What is composed of peptidoglycan

Answer 22

Cell wall in bacteria

Question 23

What is the gram stain

Answer 23

Determines gram positive (purple) and gram negative (red) bacteria and proper antibiotic to choose

Question 24

Which bacteria stain purple (gram positive)

Answer 24

Those with thick peptidoglycan walls

Question 25

Which bacteria stains red (gram negative?

Answer 25

Those with thin peptidoglycan wall with thick outer layer of lipids and carbohydrates

Question 26

Gran stain process steps

Answer 26

1. Crystal violet added (primary stain) 2. Iodine makes purple stick to peptidoglycan layer (if present) 3. Alcohol is decolourizing agent (gram - lose colour) 4. Safranin sticks to gram- cell walls

Question 27

Gran stain process steps

Answer 27

1. Crystal violet added (primary stain) 2. Iodine makes purple stick to peptidoglycan layer (if present) 3. Alcohol is decolourizing agent (gram - lose colour) 4. Safranin sticks to gram- cell walls

Question 28

Penicillin kills which gram bacteria

Answer 28

Gram positive

Question 29

Which bacteria-toxin

Answer 29

Endotoxin = gram negative Exotoxin = gram positive

Question 30

Narrow Spectrum antibiotics

Answer 30

Affects small range of bacteria (each target specific one)

Question 31

Broad spectrum antibiotic

Answer 31

Affects large range of bacteria, also kills natural microbiota -> increases risk of opportunistic infections (ex yeast infections)

Question 32

Penicillin mechanism

Answer 32

Cell wall inhibitors (gram positive)

Question 33

Streptomycin (antibiotic) mechanism

Answer 33

Inhibits protein synthesis (broad spectrum, tuberculosis

Question 34

Where is the chromosome in prokaryotes

Answer 34

Nucleoid region

Question 35

Plasmids are and can

Answer 35

Smaller circular dna fragments (no genes essential for survival) and can be transferred between bacterial cells (conjugation)

Question 36

Why carry plasmid through evolution if not necessary?

Answer 36

Bc could be advantageous (ex antibiotic resistant gene -> gets passed on and more have it)

Question 37

Antibiotic resistant bacteria grow how

Answer 37

The more antibiotics used, the greater the "selective pressure". Antibiotics create an enviro which favours growth of resistant bacteria by killing non resistant ones

Question 38

How fast can antibiotic resistant bacteria multiply

Answer 38

Once resistance established, rapidly evolves bc rapidly multiplies. Overnight, one can multiply to become a million