Prokaryotic S&F

Question 1

List structure of plasma membrane in prokaryotes

Answer 1

• Phospholipid bi-layer
• Integral protein
• Peripheral protein
• Hopanoid
• Oligosaccharide
• Hydrophobic alpha helix

Question 2

Describe structure of peptidoglycan layer

Answer 2

1. NAM + NAG repeated & joined by B-1,4-glycosidic bond (like backbone)
2. Peptide side (tetra AA) chain binds on NAM
3. Peptide interbridge binds onto 2x peptide chains

Question 3

What structure does lysozyme and penicillin act on?

Answer 3

Lysozyme: break B-1,4-glycosidic bonds => holes in CWall = lysis
Penicillin: break peptide interbridge => decrease structural integrity of CWall = cell die

Question 4

Difference bw cell walls (CW) of gram +ve & -ve bacteria

Answer 4

+ve: Thick cell wall (stain purple)

-ve: Thin cell wall (stain pink). Also have outer membrane superficial to CW

Question 5

Describe attachment of flagella hook to cell surface of gram -ve micro-o

Answer 5

Basal body has components which attach to diff. structures in gram -ve
L ring = Lipopolysaccharides (LPS)
P ring = peptidoglycan layer
MS = plasma membrane
C = cytoplasm

Question 6

List several functions for outer mem. (LPS) in gram -ve bacteria.

Answer 6

• Protection from host defences e.g.antibodies (O antigen)
• Create -ve charge on cell surface
• Stabilise outer mem. structure (lipid A)
• Endotoxin (lipin A)
• more permeable than plasma memb.

Question 7

Describe arrangement of genetic Info in bact.

Answer 7

Tightly coiled double-stranded circular DNA w/out membrane

Question 8

Structure of capsule and slime layer

Answer 8

Caps: organised polysaccharides = hard to remove
Slime: unorganised = easy to remove

Question 9

Function of capsule and slime layer

Answer 9

• Attach to surfaces
• Motility
• Protect from changes or chemicals in enviro, viral infection or predation, host defenses

Question 10

How does bacterial flagellum move?

Answer 10

By rotation powered by proton motive force

Question 11

How is a motile bacteria able to sense an attractant & move twds it?

Answer 11

Chemoresptors on surface cells - detect [attractant]

Question 12

Function of plasma membrane

Answer 12

• separates cell from enviro.
• Selective permeable memb.
• Metabolic processes (e.g. endocytosis)
• Sensory

Question 13

Define plasmid

Answer 13

Circular DNA molecules (smaller than nucleoid)

Question 14

Differentiate bw gram +ve & -ve bact.

Answer 14

+ve: purple, thick peptidoglycan, has techoic acids, Sensitive to penicilin, no outer membrane, no LPS
-ve: pink, thin, no techoic acids, not sensitive, has outer membrane, has LPS

Question 15

Role of inclusion bodies

Answer 15

Stores organic or inorganic materials for future use

Question 16

Role of plasmid to the bacteria’s genetics

Answer 16

May carry genes - carry selective adv. (e.g. drug resistance)
(Transfer of plasmid in mating)

Question 17

What is the role of the cell wall in osmotic protection?

Answer 17

protects against osmotic lysis (hypotonic solution = Hi [solute in cell]

Question 18

Which organic inclusion body is a source for C?

Answer 18

Poly-B-hydroxybutyrate

Question 19

Which inorganic inclusion body synthesis nucleic acids?

Answer 19

Polyphosphate granules

Question 20

Photosynthetic bacteria can store energy in inorganic inclusion bodies called?

Answer 20

Sulphur granules

Question 21

Which organic inclusion body store CO2 & RuBisCO enzyme in photosynthetic bacteria?

Answer 21

Carboxysomes

Question 22

Which organic inclusion body contains air for boyancy?

Answer 22

gas vacuole

Question 23

Which inorganic inclusion body changes due to magnetic fields?

Answer 23

Magnetosomes

Question 24

Role of nucleoid in bact. cells

Answer 24

Info required to make new cells

Question 25

Why is peptidoglycan layer rigid?

Answer 25

Cross-liking w/ neighbouring NAM-NAG chains

Question 26

6 types of flagella

Answer 26

1. Monotrichous: 1 flagellum
2. Polar flagellum: flagellum @ one end
3. Amphitrichous: 1 flagellum @ each end of cell
4. Lophotrichous: cluster of flagella at one (or both) ends
5. Peritrichous: spread on entire surface of cell
6. amphi-lophotrichous: 2+ from 2 ends

Question 27

Describe attachment of flagella hook to cell surface of gram +ve micro-o

Answer 27

basal body attaches onto plasma membrane

Question 28

List spore structure

Answer 28

Protein coat (w/ receptors), core, exosporium, cortex (contain peptidoglycan)

Question 29

Why would a bacteria undergo sporogenesis? And what happens after?

Answer 29

receptors on plasma membrane detects changes in environment (w/ receptors) that makes it unfavourbale to live. If receptors detect favourable living cond. cell undergoes germination.