L3 - Membranes, Ions, Waters and Proteins

Question 1

Water

Answer 1

O carries slight negative charge

Soild = crystal structure - floating ice acts as insulator .

Question 2

The ions

Answer 2

APs + Energy store (secondary active)

Physiological: Na, K, Cl
Biochemical: Mg
Both: Ca.

Question 3

Ions in aqueous solution

Answer 3

Positive ions - O align to maximise interaction, creates primary hydration shell and H creates the secondary and vice versa.

Question 4

Ion radius

Answer 4

Charge density

Smaller ion = higher the density = larger shell = lower mobility .

Question 5

Ion concentration inside/outside the cell (Na, K, Ca, Cl)

Answer 5

Na 150-15 (10:1)
K 5-100 (1:20)
Ca 2-0.0002 (10000:1)
Cl 150-13 (11.5:1).

Question 6

Pumps (5)

Answer 6

Against gradient

ATP

Primary active transport

Slow

Mostly cations.

Question 7

Na-K-ATPase (Sodium) pump (2)

Answer 7

25% of cell ATP

1 ATP = 3 Na out/2 K in .

Question 8

Carriers (3)

Answer 8

Secondary active transport

Energy used from conc gradient

Efficient .

Question 9

Ion channels (4)

Answer 9

Transmembrane

Passive

Selective

Gating (Voltage/Ligand).

Question 10

Voltage-gated channels

Answer 10

Pore > Sensor > Coupling mechanism > INACTIVATION mechanism

Tetramer (4 equivalent subunits).

Question 11

Ligand-gated channels

Answer 11

Pore > Ligand site > Coupling mechanism > DESENSITISATION mechanism

Pentamer (5 similar subunits).