3. The Cell Membrane

Question 1

what is the structure of the cell membrane

Answer 1

phospholipid bilayer

Question 2

what does the fluid mosaic model describe

Answer 2

membrane as being fluid like with a mosaic of proteins floating inside

Question 3

what are the 4 components of the cell membrane

Answer 3

phospholipid bilayer
membrane proteins
interior protein network
cell-surface markers

Question 4

describe the phospholipid bilayer component of cell membranes

Answer 4

every cell membrane has a phospholipid bilayer and many components of membrane are embedded in this bilayer

Question 5

describe the membrane proteins component of cell membranes

Answer 5

proteins float in lipid bilayer

Question 6

what are the 2 membrane proteins in the lipid bilayer

Answer 6

integral protein

peripheral proteins

Question 7

how are the 2 membrane proteins attached in the cell membrane

Answer 7

integral proteins embedded in the membrane

peripheral proteins associated with surface of the membrane

Question 8

describe the interior protein network component of cell membranes in terms of its function

Answer 8

intracellular proteins provide structural support to the membrane

Question 9

describe the cell-surface markers component of cell membranes in terms of what it consists of

Answer 9

glycoproteins and glycolipids that act as cell identity markers

Question 10

how does phospholipids form bilayers

Answer 10

spontaneously

Question 11

what are phospholipids composed of

Answer 11

2 fatty acids and a phosphate group to a 3C glycerol molecule

Question 12

describe the solubility and polarity of the different parts of the phospholipid

Answer 12

phosphate group = hydrophilic & polar

fatty acids = hydrophobic & non-polar

Question 13

what effect does unsaturated fatty acids have on the membrane fluidity

Answer 13

more fluid

Question 14

what effect does saturated fatty acids have on the membrane fluidity

Answer 14

less fluid

Question 15

what other factor other than unsaturated/saturated fats affect the membrane fluidity

Answer 15

temperature

increase temp = increase fluidity

Question 16

what is a type of passive transport

Answer 16

diffusion

Question 17

is energy required for passive transport

Answer 17

no

Question 18

what is diffusion

Answer 18

moving a substance along chemical/electrical gradient

Question 19

what does the cell membrane act as a barrier for and what does it allow access

Answer 19

hydrophilic polar molecules blocked

hydrophobic substances allowed to diffuse through

Question 20

can ions and large hydrophilic molecules pass through phospholipid bilayer

Answer 20

no

Question 21

what assists ions and large hydrophilic molecules to pass through phospholipid bilayer - 2 types

what is this process called

Answer 21

via proteins - carrier and protein channels

facilitated diffusion

Question 22

what are the 3 types of passive transport

Answer 22

diffusion

facilitated diffusion

osmosis

Question 23

what are 2 types of passive transport proteins and how do they function

Answer 23

channels = allow diffusion of ions via protein channel

carriers = bind to molecules they transport

Question 24

what is osmosis

Answer 24

water moving across the membrane to a high conc of solutes or low conc of water

Question 25

where will water move to via osmosis

Answer 25

to area with higher solute conc or low water conc

Question 26

what is active transport

Answer 26

uses energy to move substances against conc gradient

Question 27

what are the 3 types of active transport proteins

Answer 27

uniporters symporters antiporters

Question 28

what are uniporters in terms of what they do

Answer 28

transport specific molecules in one direction

Question 29

what are symporters in terms of what they do

Answer 29

transport 2 molecules in the same direction

Question 30

what are antiporters in terms of what they do

Answer 30

transport 2 molecules in opposite directions

Question 31

what does the sodium-potassium pump do

Answer 31

uses ATP and moves sodium out of the cell and potassium into the cell against conc gradients

Question 32

how many sodium and potassium are pumped in and out via the Na-K pump

Answer 32

3 Na atoms out for every 2 K atoms that enter the cell

Question 33

can large quantities of substances pass through the membrane via diffusion

Answer 33

no

Question 34

how do large quantities of substances pass through the membrane

Answer 34

endocytosis

Question 35

how do large quantities of material leave the cell

Answer 35

exocytosis

Question 36

what is endocytosis in terms of how it works

Answer 36

cell membrane surrounding the material and pinching off to form a vesicle

Question 37

what is exocytosis in terms of how it works

Answer 37

material released from cell when vesicle fuses with the membrane