DLA 4

Question 1

What is a planar lipid raft?

Answer 1

They are short-lived

They contain cholesterol, glycosphingolipids, and sphingomyelin

Question 2

What are Caveolae?

Answer 2

Lipid rafts that form invaginations in the PM

it is long-lived and stabilized by caveolins

Question 3

What is the function of lipid rafts?

Answer 3

They can facilitate signal transduction

viral infection

Question 4

What if a membrane does not have any cholesterol?

Answer 4

FA composition controls fluidity

Question 5

What are the high affinity transporters of glucose?

Answer 5

GLUT 1,3, and 4

Question 6

What are the low affinity transporters of glucose?

Answer 6

GLUT 2 and 5

Question 7

What makes up the GLUT transporters?

Answer 7

12 transmembrane alpha helices

Question 8

What GLUT transporters have constant uptake of glucose even at low concentrations?

Answer 8

GLUT 1 and 3

Question 9

GLUT-1 is found where?

Answer 9

RBC, BBB, and kidneys

Question 10

GLUT-3 is found where?

Answer 10

The brain

Question 11

Explain GLUT-1 deficiency

Answer 11

A rare metabolic encephalopathy that can be tested using RBC

symptoms:

microcephaly
epilepsy-like seizures

Question 12

GLUT-2

Answer 12

can transport large amount of glucose

found in intestinal cells- release of mono into portal vein

liver- glucose uptake

pancreatic beta cells- measuring glucose levels in the blood

renal tubular cells- re-uptake of glucose

Question 13

GLUT-4

Answer 13

Found in fat cells, skeletal cells, and heart

Insulin mobilizes GLUT-4 and allows for influx of glucose into the cell

Question 14

Steps of GLUT-4 mobilization?

Answer 14

1. insulin binds to receptor
2. recruitment of glucose transporters to PM
3. increased uptake of glucose
4. decreased insulin = glucose transporters will leave PM
5. form to endosome

Question 15

GLUT-5

Answer 15

Low-affinity

prefers fructose but will transport glucose if in high levels

found in intestinal cells and seminal vesicles

Question 16

What is primary active transport?

Answer 16

For each pumping process 1 ATP is needed to move a molecule against the gradient

Question 17

What is secondary active transport?

Answer 17

SCT is coupled with the Na/K ATPase

transports both sodium and another molecule

Question 18

What is a ABC transporter?

Answer 18

ATP binding cassette

Question 19

Why are ABC transporters used?

Answer 19

ABC transporters allow the active transport of
molecules from the cytosol to the extracellular space:
this process needs hydrolysis of ATP.

normally lipids

Question 20

Describe the CFTR?

Answer 20

it is a gated channel with a pore for Cl- ions

it will open and close with a stimulus

some ATP is cleaved, but still considered passive transports

Question 21

cystic fibrosis and CFTR deficiency?

Answer 21

Salty skin is a indicator of a CFTR deficiency of a newborn

other symptoms:

poor growth
lung infections
male infertility 
chronic pancreatitis 
steatorrhea

Question 22

What happens during a CFTR deficiency?

Answer 22

Cl- and Na+ are stuck in the sweat, but these ions normally flow back into the cells

Question 23

Test to determine cystic fibrosis?

Answer 23

Sweat test

measure the amount of NaCl in the sweat