Lipids and Membranes

Question 1

How does cholesterol affect a membrane?

Answer 1

Since it is amphipathic it can fit between the phospholipids and it makes it harder to move things across (less permeable)

Question 2

Are lipids soluble?

Answer 2

No

Question 3

Are lipids polymers?

Answer 3

No

They are not made of monomers

Question 4

What do phospholipids and fats have in common?

Answer 4

A glycerol backbone

Question 5

Steroid structure

Answer 5

Four hydrophobic rings

addition of a hydrophilic hydroxyl group

Question 6

What is cholesterol?

Answer 6

A steroid

Question 7

What aspect of phospholipids is the most important to formation of bilayers?

Answer 7

Amphipatheic

Question 8

What is the most permeable type of bilayer?

Answer 8

short and unsaturated

the kinks in unsaturated create more space

Question 9

What is the least permeable type of bilary?

Answer 9

long and saturated

the long tail increases the force of Van der Waals interactions between the hydrophobic tails

Question 10

What crosses lipid bilayers the fastest?

Answer 10

Small, nonpolar molecule (O2)

Question 11

What crosses bilayers the slowest?

Answer 11

ions

Question 12

What do you want more of in the bilayer when it is cold?

Answer 12

Unsaturated phospholipids

more kinks=more space=less van der waals force=more permeability

Question 13

Is facilitated diffusion passive?

Answer 13

Yes

Question 14

If water rushes into the cell, what does that make the solution on the outside of the cell?

Answer 14

Hypotonic

lower in solute so water moves into hypertonic cell

Question 15

If water rushes out of the cell, what does that make the solution on the outside of the cell?

Answer 15

Hypertonic

higher in solute so water moves out of the hypotonic cell

Question 16

If water rushes into the cell, what does that make the solution on the inside of the cell?

Answer 16

Hypertonic

higher in solute so water rushes in

Question 17

Fats structure

Answer 17

Composed of 3 fatty acids linked to glycerol

Question 18

What do fatty acids have?

Answer 18

A carboxyl group attached to the hydrocarbon chain

Question 19

What is glycerol?

Answer 19

An alcohol

Question 20

How are fats formed?

Answer 20

Dehydration reaction between carboxyl group of fatty acid and hydroxyl group of glycerol

Question 21

Are fats amphipathic?

Answer 21

No since oxygen is buried within molecule

Question 22

What are fats good for?

Answer 22

Long term energy storage due to all the energy stored in the nonpolar bonds

Question 23

Are steriods amphipathic?

Answer 23

They normally have a polar group attached to the four ring structure

Question 24

Why do steroids need to be polar?

Answer 24

In order to move in and out of cells if they are going to be used as a hormone

Question 25

uses of sterioids

Answer 25

1. hormones
2. constituents of cell membrane
3. starting point for synthesis of molecules

Question 26

Fluid mosaic model

Answer 26

the membrane is not a solid barrier, molecules are free to move around like buoys

Question 27

Channel Proteins

Answer 27

facilitate diffusion

help ions diffuse in a directional manner through electrochemical gradient

Question 28

Integral membrane proteins

Answer 28

proteins that have segments facing both the interior and the exterior of the cell

Question 29

Peripheral membrane proteins

Answer 29

bind to membrane without passing through it

Question 30

Detergent

Answer 30

small, amphipathic molecule that can form miscelles

water soluble

Question 31

aquaporins

Answer 31

channels that allow water to cross the plasma membrane 10x faster than by diffusion alone

Question 32

Gated channels

Answer 32

open and close in response to a signal

Question 33

Carrier proteins

Answer 33

carrier proteins undergo shape changes that selectively pick up a solute on one side of the membrane and then drop it off on the otherside

still works by diffusion

Question 34

Pumps

Answer 34

perform active transport and go against the concentration gradient

Ex: sodium-potassium pump

Question 35

What do all forms of facilitated diffusion require?

Answer 35

A carrier protein

Question 36

Secondary transport

Answer 36

uses another molecule’s concentration gradient to pump uphill

Question 37

Primary transport

Answer 37

pumping solutes from an area of lower concentration to higher concentration using energy

Question 38

How does sodium potassium pump work?

Answer 38

three sodium cations are pumped out

two potassium cations are pumped in

Question 39

What does the sodium potassium pump make the inside of the cell?

Answer 39

Net negative