Term 1- Lec 6- Membrane Transport

Question 1

What type of molecules pass the cell membrane via simple diffusion?

Answer 1

Small, non-polar (hydrophobic) molecules

Question 2

What are the two types of membrane proteins that mediate transport?

Answer 2

Channel and Carrier proteins

Question 3

Another name for Passive Diffusion

Answer 3

Facilitated Diffusion

Question 4

Passive transport

Answer 4

Does not require energy and the molecules move down their concentration/electrochemical gradients

Question 5

Direction of molecules in Active Transport

Answer 5

Against their respective gradients

Question 6

T/F: Uncharged molecule transport is determined by their concentraion and electrochemical gradients

Answer 6

FALSE; Uncharged molecules do not have a charge therefore an uneffected by electrochemical gradients.

Question 7

The types of active transport and their differences

Answer 7

• 1º active transport: Uses ATP as it’s E source

* 2º active transport: Uses E from an electrochemical gradient.

Question 8

T/F: Channel proteins bind to thier solutes

Answer 8

False; their solutes pass through them as long as their open.

Question 9

Acetylcholine-gated ion channels

Answer 9

Located in muscle cells, when acetylcholin binds to the channel, the gate opens and Na+ enters the cell

Question 10

Uniport Carriers

Answer 10

A single molecule moves

Question 11

Symport Carriers

Answer 11

Simultaneous transport of 2 different molecules. A form of Coupled Transport

Question 12

Antiport Carriers

Answer 12

Transport of two different molecules in opposite directions. aka “Exchangers”. A form of Coupled Transport

Question 13

The GLUT protein family proteins are what type of __-port carrier

Answer 13

They are all Uniporters

Question 14

The GLUT protein family proteins exhibit what kind of transport

Answer 14

Passive Transport—Carrier Proteins

Question 15

Low Km = what affinity

Answer 15

High affinity

Question 16

High Km = what affinity

Answer 16

Low affinity

Question 17

Location of GLUT1

Answer 17

Brain, Erythrocyte, placenta, fetal tissue

Question 18

Location of GLUT2

Answer 18

Liver, Kidney, Intestine, Pacreatic ß-cells

Question 19

Location of GLUT3

Answer 19

Brain

Question 20

Location of GLUT4

Answer 20

Muscle, adipose tissue.

Question 21

Km of GLUT1

Answer 21

High affinity/ Low Km- allows for constant uptake

Question 22

Km of GLUT2

Answer 22

Low affinity/ High Km

Question 23

Km of GLUT3

Answer 23

High affinity/ Low Km- allows for constant uptake

Question 24

Km of GLUT4

Answer 24

Intermediate affinity (insulin regulated). They are recruited to cell surface by insulin signal

Question 25

What is unique about GLUT4 compared to the rest of it's protein family?

Answer 25

GLUT4 is not always present on it's cell's surfaces. It is insulin-regulated. It is in vesicles awaiting an insulin signal to bring it to the surface.

Question 26

Tight Junctions do what two things in epithelial cells?

Answer 26

1. Establish directionallity in cells | 2. Prevent apical proteins from migrating to basolateral locations (establishing direction)

Question 27

Glucose transport between adjacent cells

Answer 27

Paracellular Transport

Question 28

Glucose transport in via apical membrane and out via basolateral membrane

Answer 28

Transcellular Transport

Question 29

What are the three membrane proteins used in Glucose transport from lumen to bloodstream? What type of transport are they?

Answer 29

Apical: Na-Glucose Transporter—2º active transport—Symport Basolateral: Na/K ATPase—1º active transport—Antiport & GLUT2—Passive transport—Uniport

Question 30

Movement of Na+ at apical surface

Answer 30

2 Na+ move Into the enterocyte ALONG it's gradient. E used to move Glucose into enterocyte

Question 31

Movement of Na+ at basolateral membrane

Answer 31

3 Na+ move out of the enterocyte AGAINST it's gradient. Uses ATP to maintain Na+ gradient.

Question 32

Movement of K+ and where does this occur

Answer 32

Basolateral membrane. 2 K+ moves into the enterocyte.