Microbial Structure

Question 1

capsule

Answer 1

loose polysaccharide structure
protects cell from phagocytosis
protects cell from desiccation

Question 2

pili/fimbriae

Answer 2

composed of oligomeric piling proteins
appendage used for bacterial conjugation forms tube/bridge to enable transfer of plasmids between bacteria
highly antigenic
plays role in attachment

Question 3

Flagellae

Answer 3

organs of locomotion
composed of flagellin protein
20nm thick helical tube
driven by rotary engine at anchor point on inner cell membrane

Question 4

spores

Answer 4

hard multilayered coats making spore difficult to kill
adapted for long term survival allowing regrowth under suitable conditions
triggered by adverse environmental conditions

Question 5

slime

Answer 5

polysaccharide material
secreted by some bacteria growing I biofilms
protects against immune attack
protects against eradication by antibiotics

Question 6

What is gram staining based off

Answer 6

chemical and physical properties of the cell walls

Question 7

primary stain: crystal violet dye

Answer 7

stains all bacterial cells purple

Question 8

trapping agent: grams iodine

Answer 8

forms CVI complexes in the cell wall

Question 9

decolorisation: alcohol/acetone

Answer 9

interacts with lipids In cell wall
GRAM -VE = loses outer LPS layer; exposes thin inner PGN layer; coloured complexes mainly wash away
GRAM +VE = becomes dehydrated and traps the complexes in thicker PGN layer of cell wall

Question 10

Counterstain: safranin

Answer 10

GRAM -VE = pink/reddish

GRAM +VE = Purple

Question 11

Name me the cell wall components

Answer 11

Peptidoglycan PGN
Lipoteichoic Acid LTA
Lipopolysacchride LPS
Outer membrane proteins OMPS

Question 12

Bacteria replication process

Answer 12

Reproduce by binary fission
Genetic information found in circular DNA
DNA is a self replicating molecule
Circular DNA - replication starts at ‘origin’
replicates in two directions
2 forks split off from origin and meet at bottom

Question 13

4 phases of bacterial growth

Answer 13

Lag - small increase (active growth, reproduction)
Log - big increase (uniform replication)
Stationary - flat (exhaustion of nutrients)
Death - decrease

Question 14

define transformation

Answer 14

some bacteria are capable of taking up DNA from their environment

Question 15

define transduction

Answer 15

involves the exchanging of bacterial DNA through bacteriophages

Question 16

conjugation

Answer 16

one bacterium connects itself to another through pilus

Question 17

cocci

Answer 17

spherical

Question 18

bacilli

Answer 18

rod shaped

Question 19

spiral

Answer 19

helical rod

Question 20

viral structure components

Answer 20

nucleic acid
capsid
envelope
spikes

Question 21

capsid

Answer 21

protein coat/shell
protein subunits capsomeres - aggregated protomeres
shapes:
- rod like 
- polyhedral
-complex

Question 22

envelope

Answer 22

amorphous structure
lipid
protein
carb
eg herpes

Question 23

spikes

Answer 23

Glycoprotein projections arising from envelope

Glycoprotein projections arising from envelope

Question 24

6 steps of viral replication

Answer 24

assembly - viral components and enzymes are produces and begin to assemble
maturation - virus fully develops
release

Question 25

adsorption

Answer 25

virus binds to host/highly specific

Question 26

penetration

Answer 26

virus injects into genome by:

• fission
• binding
• ingestion

Question 27

replication

Answer 27

capsid digested by proteolytic enzymes, viral genome replicates using host cellular machinery

Question 28

assembly

Answer 28

viral components and enzymes are produces and begin to assemble

Question 29

release

Answer 29

occurs at site of nucleic acid replication
viral enzymes break down bacterial wall
from RNA as they are and DNA as cells autolyse and in inclusion bodies
• Viruses migrate to either plasma membrane or nuclear membrane
• Envelopes formed around nucleocapsids by “budding” of cell membrane
• Slow continuous release of mature viral particles • No inclusion bodies

Question 30

3 main helminth groups important in humans

Answer 30

– Cestoda: tapeworms
– Trematoda: flukes
– Nematoda: roundworms