Pumps & Transporters

Question 1

What is the two types of membrane transport diffusion

Answer 1

1. Simple diffusion
2. Facilitated diffusion

Question 2

Define simple diffusion

Answer 2

Molecules move on own from high to low concentration until equilibrium is reached

Question 3

What molecules can pass w/ simple diffusion

Answer 3

Non polar & lipid soluble molecules that can penetrate lipid bilayer

Question 4

What sets the rate of simple diffusion

Answer 4

Concentration of solute

Question 5

Define facilitated diffusion

Answer 5

Hydrophilic molecules that can not pass through lipid bilayer & requires channels & transporters

Question 6

What is the two different types of facilitated diffusion & define

Answer 6

Passive diffusion: high to low concentration
Active transport: low to high concentration & requires energy

Question 7

What sets the pace for passive diffusion

Answer 7

It is selective & saturable (concentration does not increase rate)

Question 8

What is the two types of active transport

Answer 8

Primary transport: used energy directly
Secondary transport: transport that uses energy indirectly using the electrochemical gradient

Question 9

What is the 3 classes of transport w/ examples

Answer 9

1. Uniporter: one molecule & GLUT1
2. Anti porter: 2 molecules in different directions & Na/K ATPase
3. Symporter: 2 molecules move in same direction & SGLT1

Question 10

What is difference between paracellular & transcellular transport

Answer 10

Paracellular transport: between cells w/ gap & tight junctions a passive process due to [ ]
Transcellular transport: across cells & active process w/ pumps, transporters & channels

Question 11

What is the four transporters used in glucose transport

Answer 11

GLUT2
Na/K ATPase
SGLT1
CFTR

Question 12

What is the method of glucose uptake

Answer 12

1. Facilitated transport via symporter SGLT1 of glucose & Na due to e chemical gradient created by Na/K ATPase
2. Active transport via antiporter for Na/K ATPase
3. Facilitated transport via uniporter GLUT2 for glucose, galactose & fructose into blood & maintain low glucose [ ]
4. CFTR for Cl transport from high to low [ ] - move out of cell

Question 13

What channels regulate CFTR

Answer 13

Phosphorylation of protein kinase

Question 14

What is the effect of phosphorylation on CFTR

Answer 14

Increase channel permeability & expression that increase chloride transport

Question 15

What is the 2 structure of inactive G protein

Answer 15

G protein subunits: alpha, beta & gamma
Alpha subunit bound to GDP

Question 16

How is a G protein activated

Answer 16

1. Ligand binds to receptor
2. Alpha subunit release GDP & binds to GTP & release from beta & gamma subunit

Question 17

How is a G protein inactivated

Answer 17

Alpha subunit interact & hydrolyse GTP to GDP & recombine to other subunits

Question 18

What is the 3 different types of G protein

Answer 18

1. Gq: activated phospholipase C
2. Gs: stimulate adenylyl cyclase
3. Gi: inhibit adenylyl cyclase & - feedback to Gs

Question 19

How does a G protein activate CFTR

Answer 19

1. Gs stimulate adenylyl cyclase
2. Adenylyl cyclase binds to cAMP
3. cAMP activates protein kinase A & phosphorylate CFTR that allows Cl transport

Question 20

What is the effect of cholera

Answer 20

1. Cholera activates cAMP & activates CFTR
2. Cholera release toxins that binds to enterocytes
3. The endocytosis & cleave A1 & 2
4. A1 activates enzymes, Gs protein & adenine dinucleotide & locks into activate form
5. CFTR allows for Cl efflux, waters & Na follows leading to diarrhoea