Microbiology

Question 1

Prokaryotic

Answer 1

• Nucleoid (double stranded DNA)
• 70s
• Cell membrane
• Cell wall (peptidoglycan - may be degraded by lysosomes)
• Flagella/pilli
• Plasmid (addition DNA capable of autonomous replication in g-ve)
• Mesosome (vesicles formed by invagination of plasma membrane - cell wall formation/chromosome rep)

Question 2

What does pro lack that eu has

Answer 2

Nuclear membrane
Membrane-bound organelles
Nucleolus

Question 3

peptidoglycan

Answer 3

• provides rigidity
• important for rep and survival in hostile conditions
• infection causes peptidoglycan to interfere with phagocytosis, stim mitosis of lymphocytes and becomes pyrogenic

Question 4

g+ve

Answer 4

predominantly aerobic

- turns purple with stain (trapped in THICK pep wall)

Question 5

g-ve

Answer 5

predominantly anaerobic

• counterstained into red
• THIN pep wall

Question 6

bac cell division

Answer 6

= binary fission

- septum (cross wall) produced

Question 7

morphological classification of pro

Answer 7

from incomplete cleavage of septum

coccus → spherical (staphylococcus)

bacillus → rod-shaped (e coli)

spirillum → snake-like/helical (t pallidum)

Question 8

spores

Answer 8

g+ve (NOT g-ve)

• encases bac/fungal → resistant to env factors
• DORMANT

Question 9

morphological classification of bac

Answer 9

• coccus (spherical) - staphylococcus (chain); streptolococcus (cluster)
• Bacillus (rod-shaped) - e.coli
• Spirillum (helical) - T.pallidum

Question 10

virulence factor of bacteria

Answer 10

invade, infect, evade

Question 11

local effects of bac

Answer 11

• prod enz (exotoxins→prod by g-/+ve)
• damage host cells & cellular components
• forms an abscess (from pus prod bac)

Question 12

systemic effects of bac - septicaemia

Answer 12

wide spread destruction caused by absorption of bac/toxins in blood

Question 13

systemic effects of bac -endotoxin

Answer 13

released by g-ve → triggers immune response → BV dilated → sepsis

Question 14

virus capsid

Answer 14

protein coat containing nucleic acid genome

- withstands harsh env

Question 15

virus envelope

Answer 15

lipid membrane coat

- maintained in aq solution→transmit via fluids

Question 16

genetic form of viruses

Answer 16

DNA or RNA

Question 17

function of viruses

Answer 17

true parasites

- insert genome→hijack host cells→replicate→damage/kill cells

Question 18

viral rep

Answer 18

early phase - penetrate membrane→ release genome
late - genome rep
latent - extracellular infectious viruses not detected

Question 19

viral pathogenesis

Answer 19

acquisition - entry into body
1o site - infection/inflam
2o site - virus amplified & spread→ the incubation period

Question 20

what is convalescence

Answer 20

body repairs the damage

Question 21

herpes simplex viruses type 1 (HSV1)

Answer 21

normally benign, but life threatening in newborn or immunocompromised person

Question 22

rubella in pregnant women

Answer 22

genetic malformation in fetus → developmental effects

Question 23

fungi

Answer 23

• non-motile, aerobic (yeast)

- reproduce by forming spores → increase surv and spread

Question 24

pathogenesis of fungi

Answer 24

mycoses (fungal infection)

- penetrate, colonise, repro

Question 25

protozoa

Answer 25

lacks cell wall→rapid and flexible

develops into a cyst→survives harsh conditions

Question 26

what is a vector

Answer 26

something that carries a virus

Question 27

pathogen

Answer 27

organism that evades various normal defenses→causes infection

Question 28

infection

Answer 28

organism enters body→increase number and damage host

Question 29

commensalism

Answer 29

host and bac live tgt with no effect on each other’s life cycle

Question 30

parasitism

Answer 30

un-equal, live off expense of another

Question 31

symbiosis

Answer 31

mutual benefit

Question 32

opportunistic

Answer 32

healthy defences weakened→infect

Question 33

nosocomial

Answer 33

infection transmitted in hospital

Question 34

staphylococcus aureus

Answer 34

common cause of hospital infection

resistant to treatment (MRSA)

Question 35

predictors of MRSA carriage

Answer 35

hospital setting→prolonged/antimicrobial therapy…

community→recent hospitalisation/catheter

Question 36

antibiotic resistance

Answer 36

• loss effectiveness
• innate→intrinsic resistance based on mech of drug
• acquired→of resistance gene, from stimulus (exposure), changes in cell membrane, prod. enz altering antibiotic structure