Module 9

Question 1

Composition of cell membranes

Answer 1

Lipid Bilayer

Question 2

Phospholipids

Answer 2

Glycerol backbone attached to a phosphate group of 2 fatty acids

Question 3

Phosphate head

Answer 3

Hydrophilic and polar
H-bond with H20

Question 4

Amphipathic

Answer 4

Both hydrophobic and hydrophilic ends

Question 5

Hydrophilic Heads

Answer 5

Outside surface, interacts with H20

Question 6

Hydrophobic Tails

Answer 6

Isolated from contact with H20

Question 7

Liposomes

Answer 7

When phospholipids are placed in H20 with a pH of 7, they spontaneously form a cell shape

Question 8

Dynamic Cell Membranes

Answer 8

Lateral movements of lipids and other components within the membrane

Question 9

Dynamic membrane allows what

Answer 9

VESICLES to easily detach and rejoin, cells to change SHAPE and cells to ENGULF other cells and particles

Question 10

How do phospholipids move

Answer 10

Move with their tails interacting
laterally with the plane of the membrane
Rapidly

Question 11

How can Lipids move

Answer 11

Rapidly around their vertical axis, spinning around
Fatty acid rails flex and bend

Question 12

What influences the membrane fluidity

Answer 12

Composition of the membrane
Longer fatty acid tails= less fluid
NUmber of C-C bonds in the fatty acids tails

Question 13

Why are longer fatty acid tails less fluid?

Answer 13

Longer tails= more surface area for Van der Waals bonding with other tails, holding each other in place

Question 14

What makes the membrane less fluid

Answer 14

More bonding and interactions between fatty acid tails.

Question 15

What type of fatty acids have stronger Van der Walls, why?

Answer 15

Saturated fats have stronger Van Der waals
They are straight and able to pack more tightly –> More stable, less fluid

Question 16

Have one or more C-C double bonds

Answer 16

Unsaturated fatty acids
Cannot pack as tightly because of weaker Van der Waals; less stable

Question 17

What kind of fat is Animal Fat

Answer 17

Saturated, less fluid
solid at room temp

Question 18

What kind of fat is plant fat

Answer 18

Unsaturated, fluid
Liquid at room temp

Question 19

30% of membranes mass

Answer 19

Cholesterol; inserts itself into the lipid bilayer

Question 20

Is cholesterol hydrophilic or hydrophobic

Answer 20

BOTH
Amphipathic

Question 21

High temp effect on fluidity

Answer 21

Increased fluidity

Question 22

High temp effect on fluidity with the presence of cholesterol

Answer 22

Decreased fluidity, pulling phospholipids closer together

Question 23

How is homeostasis maintained by cholesterol

Answer 23

Prevents dramatic transitions in fluidity as temp increases

Question 24

Lipid Rafts

Answer 24

Defined patches of lipids that are assemble together

Question 25

Are cell membranes always uniform

Answer 25

NO

Question 26

Functions of protiens

Answer 26

Transport molecules Pass electrons to harness energy for photosynthesis and CR Enzymes Anchor other proteins to maintain cell structure and shape

Question 27

What accounts for 50% of mass of RBC membranes

Answer 27

protiens

Question 28

Transport protiens

Answer 28

Move ions and other molecules across the membrane

Question 29

Receptor protein

Answer 29

Allow the cell to receive SIGNALS from the environment

Question 30

Integral membrane proteins

Answer 30

PERMANENTLY ASSOCIATED with cell membranes -transmembrane proteins

Question 31

Transmembrane proteins

Answer 31

Span entire lipid bilayer

Question 31

What happens if you try to remove an integral protein

Answer 31

Destroys the membrane

Question 31

3 regions of integral membrane proteins

Answer 31

2 hydrophilic regions 1 hydrophobic region

Question 31

2 Hydrophilic regions on integral membrane proteins

Answer 31

Protrude from each face of the membrane in contract with the aqueous environment inside and outside the cell

Question 32

Hydrophobic region

Answer 32

Spans the hydrophobic interior of the membrane

Question 32

Peripheral membrane proteins

Answer 32

TEMPORARILY associated with the lipid bilayer or integral membrane proteins Easily removed, leaving membrane unharmed