Lipids and Membranes Flashcards Preview

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Flashcards in Lipids and Membranes Deck (39):
1

How does cholesterol affect a membrane?

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

2

Are lipids soluble?

No

3

Are lipids polymers?

No

They are not made of monomers

4

What do phospholipids and fats have in common?

A glycerol backbone

5

Steroid structure

Four hydrophobic rings

addition of a hydrophilic hydroxyl group

6

What is cholesterol?

A steroid

7

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

Amphipatheic

8

What is the most permeable type of bilayer?

short and unsaturated

the kinks in unsaturated create more space

9

What is the least permeable type of bilary?

long and saturated

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

10

What crosses lipid bilayers the fastest?

Small, nonpolar molecule (O2)

11

What crosses bilayers the slowest?

ions

12

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

Unsaturated phospholipids

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

13

Is facilitated diffusion passive?

Yes

14

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

Hypotonic

(lower in solute so water moves into hypertonic cell)

15

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

Hypertonic

(higher in solute so water moves out of the hypotonic cell)

16

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

Hypertonic

(higher in solute so water rushes in)

17

Fats structure

Composed of 3 fatty acids linked to glycerol

18

What do fatty acids have?

A carboxyl group attached to the hydrocarbon chain

19

What is glycerol?

An alcohol

20

How are fats formed?

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

21

Are fats amphipathic?

No since oxygen is buried within molecule

22

What are fats good for?

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

23

Are steriods amphipathic?

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

24

Why do steroids need to be polar?

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

25

uses of sterioids

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

26

Fluid mosaic model

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

27

Channel Proteins

facilitate diffusion

help ions diffuse in a directional manner through electrochemical gradient

28

Integral membrane proteins

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

29

Peripheral membrane proteins

bind to membrane without passing through it

30

Detergent

small, amphipathic molecule that can form miscelles

water soluble

31

aquaporins

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

32

Gated channels

open and close in response to a signal

33

Carrier proteins

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

34

Pumps

perform active transport and go against the concentration gradient

Ex: sodium-potassium pump

35

What do all forms of facilitated diffusion require?

A carrier protein

36

Secondary transport

uses another molecule's concentration gradient to pump uphill

37

Primary transport

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

38

How does sodium potassium pump work?

three sodium cations are pumped out

two potassium cations are pumped in

39

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

Net negative