Lipids and Cell Membranes

Question 1

What are the three main categories of molecules found in the lipid bilayer?

Answer 1

Glycerophospholipids, sphingolipids, cholesterols

Question 2

Three things in a glycerophospholipid/phosphoglyceride:

Answer 2

-Glycerol, phosphate, and one or more fatty acids

Question 3

Two types of fatty acids and what they look like

Answer 3

• Saturated: no double bonds

- Unsaturated: one or more double bonds that has cis config (creates a bend in fatty acid)

Question 4

How are glycerophospholipids/phosphoglycerides related to fats? How do they differ?

Answer 4

• Both have a glycerol and backbone and two fatty acids.

- They differ in having a phosphate group attached to position #3 of the glycerol

Question 5

How do you name a glycerophospholipid /phosphoglyceride? Give example

Answer 5

You call it “phosphatidyl-X” where X is the name of the molecule attached to the phosphate. Ex: Phosphotidylserine has serine attached to phosphate.

Question 6

What is the name of the glycerophospholipid/ phosphoglyceride with no molecule attached to the phosophate? What is this molecule important for?

Answer 6

Phosphotidic acid. It is an important intermediate for the synthesis of phosphatidyl lipids as well as other fats.

Question 7

What are sphingolipids related to and what are they based off of?

Answer 7

Related to glycerophospholipids and based on sphingosine.

Question 8

What is sphingomyelin?

Answer 8

A component of the myelin sheath of nerve cells.

Question 9

Sphingolipids containing single sugars are called:

Sphingolipids containing a complex carbohydrate moiety are called:

Answer 9

• cerebrosides

- gangliosides

Question 10

Steroids are:

Answer 10

Lipids that are not derived from fatty acids. In animals derived from cholesterol.

Question 11

Cholesterol is important for:

Makes up how much of the brain?

Answer 11

• Membrane stability. And is prominent part of the brain.

- 14% of dry weight of brain

Question 12

Fatty acids (single) form what?

Answer 12

Single lipid layer called a Micelle. Also known as soap.

Question 13

Integral membrane protein:

Difficult to remove from membrane?

Answer 13

protein projects through both sides of the membrane

-Yes

Question 14

Peripheral membrane protein:

Difficult to remove from membrane?

Answer 14

protein projects into only one side of the membrane. Often associated with integral membrane protein.
-No

Question 15

Anchored membrane protein:

Answer 15

protein is linked to a molecule embedded in the lipid bilayer, like a fatty acid.

Question 16

Associated membrane protein:

Difficult to remove from membrane?

Answer 16

protein associates by hydrogen bonding with an integral membrane protein.
-No

Question 17

What is an integral membrane protein that uses light, chemistry, and mechanics to move protons across a membrane barrier

Answer 17

Bacteriorhodopsin

Question 18

One can assemble artificial lipid bilayers containing compounds as a means of delivering materials into cells. These artificial systems are called:

Answer 18

Liposomes.

Question 19

These molecules are associated with numerous physiological phenomena, including uterine contraction. They are also associated with pain.

Answer 19

Prostaglandins

Question 20

What are prostaglandins made from? (the conversion of this to prostaglandins causes pain) What catalyzes the reaction?

Answer 20

Arachidonic acid in a reaction catalyzed by peripheral membrane protein known as prostaglandin synthase (COX enzyme).

Question 21

COX enzymes are inhibited by what drugs? Why?

Answer 21

Non-steroidal anti-inflammatory drugs (NSAIDS). aspirin or ibuprofen to get rid of pain.

Question 22

NSAIDS can cause what? and why?

Answer 22

Some prostaglandins are necessary for synthesis of intestinal tissue, so inhibition of them by aspirin may cause stomach irritation.

Question 23

Medications like VIOXX and CELEBREX where born and many had to be recalled, due to having a side effect of damaging heart tissue. What were they targeting?

Answer 23

COX-2 enzyme commonly found in joints, thought to cause joint pain.

Question 24

Fluidity of membrane is related to their composition.

• Shorter and unsaturated fatty acids cause membranes to be:
• Longer and saturated fatty acids cause:

Answer 24

• shorter retains fluidity at lower temperature

- longer is more rigid at lower temperature.

Question 25

The midpoint of the conversion between the solid and the fluid state is referred to as the:

Answer 25

Tm

Question 26

What does cholesterol in the membrane do to the Tm?

Answer 26

It widens the range of the transition temperature between solid and fluid state.

Question 27

Transverse diffusion:

Answer 27

Flip-flop movement of a lipid from top to bottom or vice versa of lipid bilayer.

Question 28

Lateral diffusion:

Answer 28

Lipids move along the same layer.

Question 29

What does the Na/K ATPase (Sodium Potassium ATPase) do?

Answer 29

Transports three sodiums out of the cell and two potassiums in for each cycle? It is an antiport (moving things in opposite directions).

Question 30

What type of mechanism does Na/K ATPase use and what drives the process?

Answer 30

This is an electrogenic transport mechanism and uses hydrolysis of ATP to drive the process

Question 31

Why is movement of Na and K essential for the cell?

Answer 31

To maintain osmotic balance.

Question 32

What is an example of letting molecules in without protein receptors?

Answer 32

Cholesterol entering via LDLs which attach to a receptor on cells surface and enters via receptor mediated endocytosis.