EXAM1_L5_Membranes_yTransport

Question 1

Which can pass the membrane?
O2, CO2, N2, Steroid Hormones, H20, EtOH, Glycerol, Urea, Glucose, Galactose, Fructose, H+, Na+, HCO3-, K+, Ca2+, Cl-, amino acids.

Answer 1

O2, CO2, N2, Steroids, H20, EtOH, Glycerol, Urea
NO CHARGE
SMALL
(small polar)

Question 2

Carriers vs Channels

Answer 2

CHANNELS- passive only- no binding/interaction (straight through) ie: ACH-gated Na+ channel, intestinal GLUT-2

CARRIERS: Active or passive- binding/interaction
(ie- na-k-atpase; Na-driven-glucose carrier)

Question 3

PC,PS,PI and PE are examples of ? Phosphatidylcholine example of ?

Answer 3

sphingolipids. glycerolphospholipids

Question 4

Why is there no symmetry between cytosolic side and outside?

Answer 4

glycerolphospholipids and phingolipids don’t naturally flip-flop. (Ie: PC on outside, PS on inside)
Flippases- used in apoptosis

Question 5

which molecule is thought to naturally flipflop?

Answer 5

cholesterol

Question 6

What increases membrane fluidity?

Answer 6

short Fatty acyl chains, poly-unsaturdated lipids, High temp

Question 7

give an example of a membrane protein Covalently bound? what are they considered? is it normal?

Answer 7

• lipid-linked proteins (GGT). integral protein (inside)
• Peripheral proteins are hydrogen bonded (enzymes like sucrase, lactase, maltase etc).

Peripheral proteins hydrogen bonded can be washed off with water.

Question 8

Where are membrane carbohydrates found?

What are membrane carbs made of?

Answer 8

Outside monolayer of Plasma membrane (ie glycocalyx)-

- made of glycolipids and glycoproteins (glycosylated proteins).

Question 9

Roles of glycocalyx

Answer 9

• cell recognition
• slimy lubricant
• blood clotting, egg-sperm interaction

Question 10

GLUT2 is what kind of protein?

How to get glucose in the enterocyte?

Answer 10

Glut2-Passive glucose Carrier protein (high to low).

-Na used to drive secondary active transport to move glucose against gradient into the cell.

Question 11

What keeps Glut2 and Na_glucose carrier in place? What happens if disrupted?

Answer 11

Tight junctions keep cell polarity. If disruption, intercellular transport disrupted.

Question 12

A person drinks poison suspected of disrupting cellular structure. superCool tests indicate claudin and occludin is present in urinalysis. What problems are expected?

Answer 12

A. decreased enterocyte absorption

b.

Question 13

Peripheral proteins vs Integral proteins

Answer 13

Integral- transmembrane and lipid linked proteins (channels/carriers/ggt)
Peripheral- enzymes H-bound to integral proteins (sucrase, lactase, maltase)