Chapter 7: Membrane Structure and Function

Question 1

plasma membrane

Answer 1

boundary that separates living cell from its surroundings

Question 2

most abundant lipid in membrane

Answer 2

phospholipids

Question 3

amphipathic

Answer 3

contains hydrophilic (head) and hydrophobic (tail) regions

Question 4

fluid mosaic

Answer 4

membrane is fluid structure with mosaic of protein

Question 5

who discovered the fluid mosaic model

Answer 5

singer and nicolson

Question 6

what type of studies supported fluid mosaic model

Answer 6

freeze-fracture

Question 7

as temp cools what happens to membrane

Answer 7

becomes less fluid, more solid; membrane can solidify

Question 8

which types of membranes are more fluid

Answer 8

rich in unsaturated fatty acids

Question 9

function of cholesterol in membrane

Answer 9

prevent membrane from becoming too solid when cold, too lquid when warm

Question 10

why do variations of lipid composition of membrane occur

Answer 10

adaptations to environment

Question 11

peripheral proteins

Answer 11

bound to surface of membrane, sticks out on one side

Question 12

integral proteins

Answer 12

penetrate hydrophobic core (transmembrane)

Question 13

glycolipid

Answer 13

has carbohydrate chain instead of hydrophilic head

Question 14

glycoproteins

Answer 14

carbohydrate chain bonded to protein

Question 15

6 functions of membrnae proteins

Answer 15

transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, attachment to cytoskeleton and extracellular matrix

Question 16

external carbohydrates may vary among

Answer 16

species, individuals, and cell types

Question 17

HIV requires what to enter cell

Answer 17

CD4 and CCR5 receptors

Question 18

why are some individuals resistant to HIV

Answer 18

do not have CCR5 receptors

Question 19

assymetrical distribution of proteins, lipids,and carbs in membrane determined when

Answer 19

membrane is built by ER and golgi bodies

Question 20

hydrophobic molecules can

Answer 20

dissolve in lipid bilayer and pas through membrane

Question 21

what type of molecules do not cross through membrane easily

Answer 21

polar molecules

Question 22

transport proteins

Answer 22

allow passafe of hydrophilic substances across membran; specific to a substance

Question 23

two types of transport proteins

Answer 23

channel, carrier

Question 24

channel protein

Answer 24

have hydrophilic channel that certain molecules/ions can use s tunnel

Question 25

aquaporins

Answer 25

channel protein for water

Question 26

carrier protein

Answer 26

bind to molecules, change shape, brins molecules into cell

Question 27

diffusion

Answer 27

tendency for moecules to spread out evenly into available space

Question 28

diffusion in relation to concentration gradient

Answer 28

diffuses down gradient

Question 29

osmosis

Answer 29

diffusion of water across selectively permeable membrane

Question 30

tonicity

Answer 30

ability of surrounding solution to cause cell to gain or lose water

Question 31

osmoregulation

Answer 31

control of solute concentration and water balance

Question 32

paramecium are hypertonic to environment; how do they maintain homeostasis

Answer 32

contractile vacuole

Question 33

cell wall prevents

Answer 33

lysing

Question 34

turgid

Answer 34

when no more water can diffuse into the cell (in a hypotonic solution)

Question 35

flaccid

Answer 35

limp (in an isotonic solution)

Question 36

plant cell in a hypertonic solution

Answer 36

cells undergo plasmolysis - plant wilts

Question 37

facilitated diffusion

Answer 37

transport proteins speed passive movement of molecules across membrane

Question 38

facilitated diffusion makes use of

Answer 38

channel proteins

Question 39

ion channels

Answer 39

gated channels for specific ions

Question 40

active transport

Answer 40

moves sustances against gradient, allows cell to maintain gradient different from enviroment

Question 41

active transport requires

Answer 41

energy

Question 42

examples of active transport

Answer 42

sodium-potassium pumps

Question 43

membrane potential

Answer 43

voltage difference across a membrane created by difference in distribution of anions and cations across a membrane

Question 44

electrochemical gradient drives

Answer 44

diffusion of ions across a membrane

Question 45

electrogenic pump

Answer 45

transport protein that generate voltage across a membrane

Question 46

electrogenic pump in animals

Answer 46

sodium-potassium

Question 47

electrogenic pump in plants,fungi, bacteria

Answer 47

proton pump

Question 48

electrogenic pumps help store

Answer 48

energy that can be used for work

Question 49

cotransport

Answer 49

when active transport of a solute indirectly drives transport of other solutes

Question 50

example of cotransport

Answer 50

plants use H+ gradient generated by proton pump to drive active transport of nutrients into cell

Question 51

small molecules/water tracel through membrane via

Answer 51

protein

Question 52

large molecules cross membrane in bulk via

Answer 52

vesicle

Question 53

bulk trnaspsort requires

Answer 53

energy

Question 54

exocytosis

Answer 54

transport vesicles outside cells - secretory cells

Question 55

endocytosis

Answer 55

cells takes in mecromolecules by forming vesicles from membrane

Question 56

types of endocytosis

Answer 56

phagocytosis, pinocytosis, receptor-mediated

Question 57

phagocytosis

Answer 57

cell eating - large molecules

Question 58

pinocytosis

Answer 58

cell drinking - smalll molecules

Question 59

receptor-mediated

Answer 59

recognizes/bonds to substance that is needed; binding of ligand triggers vesicle formation

Question 60

ligand

Answer 60

molecule that bonds to receptor