Prokaryotic S&F Flashcards
List structure of plasma membrane in prokaryotes
- Phospholipid bi-layer
- Integral protein
- Peripheral protein
- Hopanoid
- Oligosaccharide
- Hydrophobic alpha helix
Describe structure of peptidoglycan layer
- NAM + NAG repeated & joined by B-1,4-glycosidic bond (like backbone)
- Peptide side (tetra AA) chain binds on NAM
- Peptide interbridge binds onto 2x peptide chains
What structure does lysozyme and penicillin act on?
Lysozyme: break B-1,4-glycosidic bonds => holes in CWall = lysis
Penicillin: break peptide interbridge => decrease structural integrity of CWall = cell die
Difference bw cell walls (CW) of gram +ve & -ve bacteria
+ve: Thick cell wall (stain purple)
-ve: Thin cell wall (stain pink). Also have outer membrane superficial to CW
Describe attachment of flagella hook to cell surface of gram -ve micro-o
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
List several functions for outer mem. (LPS) in gram -ve bacteria.
- 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.
Describe arrangement of genetic Info in bact.
Tightly coiled double-stranded circular DNA w/out membrane
Structure of capsule and slime layer
Caps: organised polysaccharides = hard to remove
Slime: unorganised = easy to remove
Function of capsule and slime layer
- Attach to surfaces
- Motility
- Protect from changes or chemicals in enviro, viral infection or predation, host defenses
How does bacterial flagellum move?
By rotation powered by proton motive force
How is a motile bacteria able to sense an attractant & move twds it?
Chemoresptors on surface cells - detect [attractant]
Function of plasma membrane
- separates cell from enviro.
- Selective permeable memb.
- Metabolic processes (e.g. endocytosis)
- Sensory
Define plasmid
Circular DNA molecules (smaller than nucleoid)
Differentiate bw gram +ve & -ve bact.
+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
Role of inclusion bodies
Stores organic or inorganic materials for future use
Role of plasmid to the bacteria’s genetics
May carry genes - carry selective adv. (e.g. drug resistance)
(Transfer of plasmid in mating)
What is the role of the cell wall in osmotic protection?
protects against osmotic lysis (hypotonic solution = Hi [solute in cell]
Which organic inclusion body is a source for C?
Poly-B-hydroxybutyrate
Which inorganic inclusion body synthesis nucleic acids?
Polyphosphate granules
Photosynthetic bacteria can store energy in inorganic inclusion bodies called?
Sulphur granules
Which organic inclusion body store CO2 & RuBisCO enzyme in photosynthetic bacteria?
Carboxysomes
Which organic inclusion body contains air for boyancy?
gas vacuole
Which inorganic inclusion body changes due to magnetic fields?
Magnetosomes
Role of nucleoid in bact. cells
Info required to make new cells
Why is peptidoglycan layer rigid?
Cross-liking w/ neighbouring NAM-NAG chains
6 types of flagella
- Monotrichous: 1 flagellum
- Polar flagellum: flagellum @ one end
- Amphitrichous: 1 flagellum @ each end of cell
- Lophotrichous: cluster of flagella at one (or both) ends
- Peritrichous: spread on entire surface of cell
- amphi-lophotrichous: 2+ from 2 ends
Describe attachment of flagella hook to cell surface of gram +ve micro-o
basal body attaches onto plasma membrane
List spore structure
Protein coat (w/ receptors), core, exosporium, cortex (contain peptidoglycan)
Why would a bacteria undergo sporogenesis? And what happens after?
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.
