TOPIC 4: Nutrient Transport

Question 1

describe the cell wall of gram positive bacteria

Answer 1

glycosyl chains
s-layer
teichoic acids/peptidoglycan
cell membrane (+ proteins)

Question 2

describe the cell wall of gram negative bacteria

Answer 2

s layer
LPS
outer membrane
lipoproteins
peptidoglycan/periplasm
inner membrane (+ proteins)

Question 3

describe peptidoglycan

Answer 3

porous and permeable

Question 4

describe the outer membrane (gram negative)

Answer 4

contains porins, allows passage of nutrient molecules which are small and hydrophilic

Question 5

describe osmosis

Answer 5

movement of water from low [solute] to high [solute]

Question 6

what are aqua pores?

Answer 6

4nm
hydrophobic amino acids speed water through pores

Question 7

what is a hypertonic solution?

Answer 7

higher concentration of solute OUTSIDE cell
water moves OUT of cell

Question 8

what is a hypotonic solution?

Answer 8

lower concentration of solute OUTSIDE cell
water moves INTO cell

Question 9

what is facilitated diffusion?

Answer 9

involves a substrate specific permease/transporter
driven by concentration gradient (high to low)
permeases are HIGHLY specific and form channels t allow passage of specific solutes
substrate binding and CONFORMATIONAL changes

Question 10

what are the mechanisms of active transport?

Answer 10

COUPLED –> movement of one molecule down a concentration gradient provides energy to move a second molecule against a concentration gradient

ATP binding CASSETTE –> hydrolysis of ATO provides energy

GROUP TRANSLOCATION –> chemically modifies molecule as it enters the cell to maintain gradient