Chapter 11: Membrane Structure

Question 1

Membrane Composition

Answer 1

lipids and proteins

Question 2

Integral proteins

Answer 2

directly attached to membrane

Question 3

Peripheral

Answer 3

loosely associated with membrane

Question 4

The rearrangement of the phospholipid bilayer favors what?

Answer 4

• repair of damage
• formation of a closed compartment ( which is more favorable)

Question 5

Liposomes structure

Answer 5

phospholipid bilayer and aqueous interior

Question 6

How can phospholipids move?

Answer 6

• lateral diffusion
  -flexion
  -rotation
  -flip-floping sides ( rarely occurs)

Question 7

Phospholipid affect on membrane fluidity

Answer 7

-fatty acid chain length (shorter = more fluid)
-fatty acid
chain saturation (cis double bond = more fluid)

Question 8

Sterol affect on membrane fluidity

Answer 8

Cholesterol ( high concentration more fluid)
- if most fatty acids are unsaturated then cholesterol creates less fluidity

Question 9

Temperature affect on membrane fluidity

Answer 9

high temp ( high fluidity)
low temp ( more rigid)

Question 10

is cholesterol amphipathic

Answer 10

yes

Question 11

What is the pattern of mature membranes

Answer 11

asymmetrical

Question 12

1st step of membrane synthesis

Answer 12

in the smooth ER phospholipids are added no the cytosolic face

Question 13

2nd Step of membrane synthesis

Answer 13

scramblases randomly flip phospholipids from one face of the membrane to the other in the ER

Question 14

3rd Step of membrane synthesis

Answer 14

Flippases move specific phospholipids from the extracellular face to the cytosolic face in the Golgi. Floppases move phospholipids from the cytosolic face to the extracellular face of the Golgi

Question 15

Where do glycolipids obtain their sugar?

Answer 15

inside the Golgi

Question 16

How can integral membrane proteins be removed from membranes?

Answer 16

using detergents

Question 17

What happens when multiple amphipathic alpha helices associate?

Answer 17

form a hydrophilic pore ( integral membrane protein)

Question 18

What can a large curved beta sheet form?

Answer 18

beta barrel that spans the membrane

Question 19

Beta barrel structure

Answer 19

hydrophobic exterior and water filled interior (integral membrane protein)

Question 20

What do detergents do?

Answer 20

disrupt hydrophobic associations

Question 21

Properties of detergents

Answer 21

-Amphipathic
-Single hydrophobic chain
-Monolayer micelles

Question 22

Glycoprotein

Answer 22

protein with short, covalently attached oligosaccharide

Question 23

Proteoglycan

Answer 23

protein with one or more long oligosaccharides

Question 24

Glycolipid

Answer 24

lipid with covalently attached oligosaccharide

Question 25

Carbohydrate layer of cell surface composition

Answer 25

Glycoprotein, Proteoglycan, Glycolipid

Question 26

Carbohydrate later of cell surface function

Answer 26

protection from chemical and mechanical damage - cell to cell recognition

Question 27

Ligands for lectins

Answer 27

proteins that bind oligosaccharide chains

Question 28

Glycocalyx

Answer 28

carbohydrate layer

Question 29

What is lectin binding responsible for?

Answer 29

recruitment of white blood cells to site of infection

Question 30

Cell Cortex

Answer 30

framework of proteins that attaches to membrane proteins, restricting their mobility

Question 31

What do tight junctions preserve?

Answer 31

the asymmetric distribution of membrane proteins