Cell Processes: Structure and Function of the Cell

Question 1

Width of the cell membrane

Answer 1

8nm

Question 2

Are proteins free moving in the plasma membrane

Answer 2

Yes

Question 3

Composition of lipids and proteins in membrane

Answer 3

50 % lipid & 50 % protein

with hydrogen bonds

Question 4

What are the three lipids in the plasma membrane

Answer 4

cholesterol, phospholipids, glycolipids

Question 5

Arrangement of lipids in plasma membrane

Answer 5

Cholesterol and glycolipids scattered among a double row of phospholipid molecules

Question 6

How many membrane lipids are phospholipids?

Answer 6

75%

Question 7

How many layers are in a phospholipid bilayer

Answer 7

2 parallel layers

Question 8

Are phospholipids polar or non polar?

Answer 8

They are amphipathic (have both a polar & nonpolar region)

Question 9

What do phospholipids do when put in water?

Answer 9

they will orientate themselves to make the lowest energy structure (nonpolar tails will spontaneously face away from water)

Question 10

What is a membrane leaflet

Answer 10

One side of the phospholipid bilayer

Question 11

Are membranes fluid

Answer 11

Yes

Question 12

How can lipids move in the membrane?

Answer 12

They can move around within the plane of the membrane leaflet

Question 13

Can lipids change between leaflets

Answer 13

Lipids rarely flip flop between membrane leaflets therefore the lipid composition of the leaflets can be asymmetric

Question 14

What effect does the a longer lipid tail have on fluidity of the membrane

Answer 14

It makes the membrane less fluid

Question 15

What do more double bonds do to the fluidity of the membrane

Answer 15

It makes it more fluid

Question 16

What forms in the membrane due to double bonds

Answer 16

Double bonds make kinks, making them pack less tightly giving more fluidity (membrane less stable)

Question 17

What are integral proteins

Answer 17

Membrane proteins that extend into or completely cross the cell membrane (they are embedded in the hydrophobic core)

Question 18

What is a transmembrane protein

Answer 18

An integral membrane protein that goes completely across the plasma membrane

Question 19

What are peripheral proteins

Answer 19

Membrane proteins attached to either inner or outer surface of cell membrane and are easily removed from it

Question 20

How can you remove a peripheral protein from a plasma membrane

Answer 20

Easily removed by changing in ionic strength as you breaking an ionic bond

Question 21

Are integral proteins polar or nonpolar?

Answer 21

They are amphipathic

Question 22

What do the hydrophobic regions of integral proteins contain?

Answer 22

non polar amino acids coiled into helices

Question 23

How to get membrane protein out of the membrane

Answer 23

break interactions between hydrophobic lipids and hydrophobic amino acids

Question 24

What is an ion channel protein?

Answer 24

An integral membrane protein that allows specific substances to move through a water-filled pore

Question 25

What is a transporter protein?

Answer 25

An integral membrane protein that changes its shape to move molecules across the membrane

Question 26

What is the membrane permeable too?

Answer 26

nonpolar uncharged molecules, small polar uncharged molecules, lipid soluble molecules

Question 27

What is the membrane NOT permeable too?

Answer 27

large uncharged polar molecules, ions

Question 28

How do lipid soluble molecules get across plasma membrane?

Answer 28

Lipid soluble molecules can interact with hydrophobic core and pass through the lipid bilayer

Question 29

How can ions and glucose cross the plasma membrane?

Answer 29

Through transmembrane proteins: Membrane proteins mediate the transport of substances across the membrane that can not permeate the hydrophobic core of the lipid bilayer

Question 30

What is the principal of diffusion

Answer 30

the random mixing of particles in a solution as a result of the particle’s kinetic energy

Question 31

How to molecules move across the concentration gradient?

Answer 31

molecules move away from an area of high concentration to an area of low concentration

Question 32

What does a grater distance in concentration between two side of the membrane do to diffusion rate?

Answer 32

it will increase the rate of diffusion

Question 33

What does increasing the temperature do to the rate of diffusion

Answer 33

increase the rate of diffusion

Question 34

What do increasing the size of a diffusing substance do to diffusion rate?

Answer 34

slows the rate of diffusion

Question 35

What does increasing surface area do to the rate of diffusion?

Answer 35

It will increase the rate of diffusion

Question 36

What do increasing the diffusion distance do to the rate of diffusion

Answer 36

it slows the rate of diffusion

Question 37

Physical limit to cell size, due to diffusion

Answer 37

20 µm

Question 38

What does a thick membrane do to the rate of diffusion

Answer 38

it slows the rate of diffusion

Question 39

What is a concentration gradient?

Answer 39

non charged molecules will diffuse down their concentration gradients (passive transport)

Question 40

What is an electrical gradient?

Answer 40

ions will be influenced by membrane potential in addition to their concentration gradient (Movement of ions will be influenced by the electrochemical gradient)

Question 41

Concentration of Na+ outside of the cell

Answer 41

150mM

Question 42

Concentration of K+ outside of the cell

Answer 42

5mM

Question 43

Concentration of Cl- outside of the cell

Answer 43

150mM

Question 44

Amount of resting energy that a cell uses to maintain a separation of charge between the cytoplasm and extracellular fluid

Answer 44

30%

Question 45

What does a gradient represent?

Answer 45

Stored energy

Question 46

Where do Na+ ions diffuse to

Answer 46

Into cell

Question 47

Where do K+ ions diffuse to

Answer 47

out of cell

Question 48

Where do Cl- cells diffuse to

Answer 48

in and out cell

Question 49

What is osmosis

Answer 49

The net movement of water through a selectively permeable membrane from a high [water] to a low [water].

Question 50

When will osmosis occur?

Answer 50

When there is a solute difference

Question 51

What feature does a membrane need to have to carry out osmosis?

Answer 51

Water permeable