Cell Bio Ch 10

Question 0

Membrane lipids are _____________.

Answer 0

Amphipathic

Has a polar (hydrophilic) and a non-polar (hydrophobic) end.

Question 1

Cell membrane composition

Answer 1

50% lipid molecules, the rest is made of protein.

Most abundant is phospholipids, others are cholesterol and glycolipids.

Question 2

Phospholipids are classified by their

Answer 2

Backbones

Phosphoglycerides have a glyceride backbone

Question 3

Cholesterol

Answer 3

Rigid ring structure with a single polar hydroxyl group and a non polar hydrocarbon chain
Stiffens the membrane

Question 4

Phospholipids ___________ form a bi-layer when they are ______________ shaped.

Answer 4

Spontaneously, cylinder

Question 5

Lipid bi-layer is a ______________ fluid.

Answer 5

Two-dimensional
Allows Lateral diffusion (left to right)
Rotation (360 degrees)
And Flip-flops (lipids rarely migrate between layers)

Question 6

Lipid bi-layer goes from a liquid to gel state in freezing temp

Answer 6

Phase transition

Question 7

______________ chain length allows tails to interact with each other, and __________________ bonds produce kinks making them difficult to pack.

Answer 7

Shorter, cis-double bonds

Question 8

Factors that effect the fluidity of a lipid bi-layer

Answer 8

Temperature=> higher temperature = more fluidity
Chain length=> shorter chain = more fluidity
Double bonds => more double bonds = more fluid
Cholesterol (found in eukaryotic membrane) => high concentration = keeps lipids from coming together and crystallizing, maintaining fluidity

Question 9

Bacterial membranes have _______ types of phospholipids in membrane and no _________.

Answer 9

One type, no cholesterol

Question 10

Lipid rafts

Answer 10

Specialized regions of the lipid layer that are enriched in certain phospholipids and proteins. Rafts are thicker than other parts of the lipid layer because they are enriched with sphingomyelin and cholesterol
May help organize proteins.

Question 11

The membrane is asymmetric with respect to

Answer 11

Lipid composition

And orientation of membrane proteins

Question 12

Phosphatidylinositol

Answer 12

Works with other membrane proteins to relay signals received from outside the cell

Question 13

Membrane protein functions

Answer 13

Transporters, anchors, receptors, and enzymes

Question 14

All membrane proteins together form

Answer 14

The integral membrane proteins

Question 15

Amphiphilic proteins that hydrophobic regions and two hydrophilic regions

Answer 15

Transmembrane proteins

Question 16

Proteins that do not extend into hydrophobic interiors and are bound to other membrane proteins through non-covalent bonds

Answer 16

Peripheral membrane proteins

Question 17

Transmembrane protein types

Answer 17

Single-pass - if protein passes through membrane once

Multi-pass - if protein passes through membrane multiple times

Question 18

A hydrophilic transmembrane pour can be creat by:

Answer 18

Multiple alpha helices

Question 19

Transmembrane proteins that often form channels

Answer 19

Beta barrels

Beta sheets rolled into closed barrels

Question 20

Porins

Answer 20

Pores created by beta barrels

Have non-polar side chains toward lipids and polar side chains on inside helping transport aqueous molecules

Question 21

Many membrane proteins are:

Answer 21

Glycosylated

Important for protein function, cell surface recognition, and cell to cell adhesion

Question 22

Thick carbohydrate layer due to glycosylated proteins

Answer 22

Glycocalyx

Question 23

Polysaccharide of integral membrane proteins

Answer 23

Proteoglycan

Question 24

Oligosaccharide bound to a lipid

Answer 24

Glycolipid

Question 25

Oligosaccharide bound to a membrane protein

Answer 25

Glycoprotein

Question 26

FRAP

Answer 26

Fluorescence Recovery After Photobleaching

Using GFP tagged proteins, bleach a section and measure the rate of diffusion