Structural Macromolecules (Dr Alderwick): Part 1 Flashcards
What is the most well studied prokaryote?
E. coli
What is the primary role of the cytoplasmic membrane (CM)?
- separates the cytoplasm from the cells enviornment
- permeability barrier
Describe the composition of the CM
- phosphatidylethanoloamine ( fatty acids)
- arranged into phospholipid bilayer
- 6-8 nanometers wide
Describe the fluid mosaic model of the bacterial cytoplasm membrane
- contains a range of diverse membrane proteins
- enzymes ( PBPs- peptidoglycan biosynthesis )
- transporters (move molecules OUT–> IN or IN—>OUT)
- site of generation and us of the proton motive force
- 2-6 atm of osmotic trudger pressure = extremely fragile
Explain briefly the architecture of the Archeal CM
- lipid tails are attached to glycerol via an either linkage
- lipids are braced with methyl (CH3) groups- isoprenes
- Phytanyl (C20) or Biphytanyl (C40) <- glycerol on both ends
- crenarchaeol - hydrocarbon moiety contaiing 5 and 6 carbon rings
Archeal CM:
- glycerol dieters made from C20 phytanyl lipids forms a ?
lipid bilayer
Archeal CM:
- diglycerol tetra ethers made from C40 Biphytanyl lipids forms a?
- lipid monolayer
Archeal CM:
- both types of membranes are extremely resistant to ? Wide spread among?
- heat denaturation
- thermophiles
Despite chemical variation in CM lipids between Archaea and Bacteria, the CM functions to ?
- form a membrane with inner and outer hydrophilic surfaces
- allows for PERMEABILITY which has its inherent problems
- anchor for membrane proteins and membrane associated proteins
- site of generating of proton motive force
What are the three major classes of transport systems for CM?
- Simple transport
- Group Translocation
- ABC transporter
Explain simple transport
- driven by the energy in the proton motive force
Explain group translocation
- chemical modification of the transported substance driven by phosphoenolpyruvate
Explain ABC transporter
- periplasmic (outside) binding proteins are involved and energy comes from ATP
ABC = ATP Binding Cassette
With the bacterial cell wall: Peptidoglycan (aka murein) there are two major classes - what are they?
- Gram-positive (ex: S. aureus)
2. Gram - negative (ex: E. coli)
Explain the study by hans christian gram for positive and negative !
- Gram + and Gram - were tested via fixation –> crystal violet–> iodine treatment–> decolorization –> counter stain safranin
- gram+ retained the initial violet colour throughout
- *gram - the colour changed as the process went on…it changed colour after the decolourization process whereas the gram + retained it