8.

Question 1

nutrient transport

Answer 1

all systems in prokaryotes require energy in some form, usually proton motive force or ATP

Question 2

simple transport

Answer 2

driven by the energy in the proton motive force

H+ on outside and OH- on inside

Question 3

Group translocation

Answer 3

chemical modification of the transported substance driven by phosphoenolypyruvate

Question 4

ABC transporter

Answer 4

periplasmic binding proteins are involved and energy comes from ATP

Question 5

Nutrient transport events

Answer 5

uniport
symport
antiport

Question 6

uniporters

Answer 6

transport in one direction across the membrane

Question 7

symporters

Answer 7

function as co transporters

Question 8

antiporters

Answer 8

transport a molecule across the membrane while simultaneously transporting another molecule in the opposite direction

Question 9

simple transport

Answer 9

lac permease of escherichia coli

• lactose in transported into e.coli by the simple transporter lac permease, a symporter - two molecules move across membrane in same direction
• activity of lac permease is energy-driven
• transports lactose and a H+ into the cell simultaneously

Question 10

group translocation

Answer 10

eg. phosphotransferase in e. coli
- sugar is phosphorylated during transport across the membrane
- moves glucose, fructose and mannose
- phosphoenolpyruvate (PEP) donates a P to a phosphorelay system
- P is transferred through a series of carrier proteins and deposited onto the sugar as it is brought into the cell

Question 11

ABC (ATP-binding cassette) transport systems

Answer 11

• involved in uptake of organic compounds (e.g. sugars, amino acids,), inorganic nutrients (e.g. sulphate, phosphate) and trace metals
• typically display high substrate specificity
• gram-negatives employ periplasmic-binding proteins and ATP-driven transport proteins
• gram-positives employ substrate-binding lipoproteins (anchored to external surface of cell membrane) and ATP-driven transport proteins

Question 12

ABC transporters

Answer 12

• solute binding protein
  
  • periplasm
  • binds specific substrate
• integral membrane (proteins) (transporter)
• ATP-hydrolyzing proteins (supply energy for the transport event)

Question 13

carrier mediated transport systems

Answer 13

• show saturation effect

- highly specific