lecture 4

Question 1

what are the 3 protein classes within the membrane

Answer 1

integral
peripheral
lipid anchored

Question 2

what are 30% of protein encoded in an animals genome?

Answer 2

membrane proteins

Question 3

what are the functions of integral proteins (3)

Answer 3

receptors
channels
transporters

Question 4

are integral proteins amphipathic

Answer 4

yes

Question 5

what kind of interactions are within the transmembrane domain (integral proteins)

Answer 5

van Der wall

Question 6

are integral proteins fixed in their location

Answer 6

no

Question 7

what is 60% of all current drug targets

Answer 7

integral proteins

Question 8

how are peripheral proteins associated with the membrane

Answer 8

weak non covalent bonds

Question 9

what are cytosolic peripheral proteins

Answer 9

enzymes / factors that transmit transmembrane signals

Question 10

how are lipid anchored proteins associated with the membrane

Answer 10

covalently bonded

Question 11

where can lipid anchored proteins be on the membrane

Answer 11

intracellular or extracellular

Question 12

what is the glycocalyx

Answer 12

the sugary layer on the outside of the membrane

Question 13

where are membrane carbohydrates (glycocalyx) primarily located?

Answer 13

extracellularly

Question 14

what does the cell cortex do

Answer 14

provides strength and support to the plasma membrane

Question 15

what cells have the cell cortex? why?

Answer 15

animal cells

all the others have cell walls, we do not

Question 16

what is spectrin

Answer 16

Fibres stretching through the membrane to create the supportive skeleton (cell cortex)

Question 17

whats the most studied animal cell

Answer 17

red blood cells

Question 18

what is ankyrin

Answer 18

a protein that anchors spectrin to the plasma membrane

Question 19

what does “fluid” mean within the membrane

Answer 19

that components can move laterally

Question 20

what does “mosaic” refer to

Answer 20

the phospholipids and proteins

Question 21

when the membrane Is cold and there is no cholesterol, what is it like

Answer 21

very rigid, might break

Question 22

when it is hot and there is no cholesterol in the membrane, what does it look like?

Answer 22

too fluid and doesn’t hold together

Question 23

what are the 3 factors that influence membrane fluidity

Answer 23

temperature
cholesterol
saturated and unsaturated fatty acids

Question 24

how can phospholipids move (direction)

Answer 24

laterally

Question 25

how would a phospholipid move from one leaflet to the other

Answer 25

flippases

Question 26

does it take longer for a phospholipid to travel laterally or between the leaflets

Answer 26

much longer between leaflets

Question 27

what is cell fusion

Answer 27

when 2 different types of cells can be fused to produce one cell

Question 28

what does cell fusion reveal

Answer 28

mobility of membrane proteins from 2 different species/cell types

Question 29

what can protein movement be limited by

Answer 29

membrane skeleton neighbouring proteins extracellular interactions

Question 30

whats the main obstacle that protein encounter

Answer 30

the membrane skeleton/cell cortex

Question 31

are epithelial cell polarized or unpolarized

Answer 31

polarized

Question 32

whats the apical membrane facing

Answer 32

the lumen/inside of tube

Question 33

whats the basal membrane facing

Answer 33

outside of tube

Question 34

what is the lateral plasma membrane for

Answer 34

cell contact/communication

Question 35

are steroid hormones free to pass the membrane

Answer 35

yes

Question 36

can glucose/sucrose pass the membrane freely

Answer 36

their transport is very slow and barely free (third one)

Question 37

what cannot pass unless a transporter is used

Answer 37

ions/charged molecules

Question 38

what molecules can freely pass

Answer 38

hydrophobic molecules

Question 39

where is there a high concentration of potassium

Answer 39

in the cell

Question 40

where is there a high concentration of chlorine and sodium

Answer 40

outside the cell

Question 41

what is simple diffusion movement dictated by

Answer 41

concentration gradients that exist

Question 42

what are the 2 passive diffusion

Answer 42

simple diffusion facilitated diffusion (carriers)

Question 43

does water diffuse

Answer 43

no it does osmosis

Question 44

what is the different between semi permeable membrane and selectively permeable membrane

Answer 44

semi permeable permits h2o but not solutes selectively permeable permits some solutes but not others - biological membranes

Question 45

what are the substances transported across membrane by simple diffusion (4)

Answer 45

gases lipid solutes (steroid hormones, fatty acids) other organic molecules

Question 46

whats the concentration gradient of osmosis

Answer 46

low to high

Question 47

what is osmosis for

Answer 47

to dilute concentrated area

Question 48

what are aquaporins

Answer 48

small integral proteins that allow water to flow passively

Question 49

how many subunits do aquaporins have

Answer 49

4

Question 50

what are aquaporin subunits lined by

Answer 50

hydrophobic amino acids

Question 51

what kind of transport are ion channels

Answer 51

passive transport

Question 52

what do ion channels look like

Answer 52

they transverse the lipid bilayer

Question 53

what is the driving force of ion channels

Answer 53

electrochemical gradient of the ions

Question 54

what 3 states can voltage gated channels be in

Answer 54

open, inactivated, and closed

Question 55

how is an inactivated state different than a closed state

Answer 55

if closed, it can be opened again if inactivated, it cannot be opened again

Question 56

what is activation

Answer 56

the opening of a channel in response to stimuli

Question 57

what does the bacterial KcsA Potassium channel allow through

Answer 57

only allows K+ through

Question 58

what does selectivity refer to

Answer 58

the ability of a channel to pass a particular particle

Question 59

why can't sodium go through the bacterial KcsA potassium channel

Answer 59

because it has a hydration sphere that wouldn't allow it to fit through

Question 60

are carrier proteins specific

Answer 60

yes

Question 61

how do glucose and amino acids get through the membrane `

Answer 61

carrier proteins

Question 62

can carrier proteins be saturated

Answer 62

yes

Question 63

whats different between simple and facilitated diffusion

Answer 63

facilitated diffusion shows saturation kinetics because there is a limited amount of carriers/transporters

Question 64

how are electrochemical gradients generated

Answer 64

active transport

Question 65

what are electrochemical gradients

Answer 65

differences in electrical charge and solute concentration

Question 66

which transport uses ATP

Answer 66

primary active transport

Question 67

what is protein in active transport

Answer 67

both an enzyme and a transporter (pump)

Question 68

where is the energy provided by in active transport

Answer 68

the hydrolysis of ATP by the ATPase on the transport protein

Question 69

what does active transport typically transport

Answer 69

inorganic ions

Question 70

what is electroneutral

Answer 70

no overall change in the cells electrical properties

Question 71

what is electrogenic

Answer 71

change in cells electrochemical properties

Question 72

whats an important point about active transport

Answer 72

the pumps move ions that can influence the cells electrical properties

Question 73

what electrogenic pump is only found in animal cells

Answer 73

Na/K ATPase

Question 74

what does the parietal cell H/K ATPase do

Answer 74

exchanges 2 H for 2 K in the stomach

Question 75

what drives the co transport of glucose

Answer 75

diffusion of Na down a concentration gradient

Question 76

what does secondary active transport use

Answer 76

a sodium gradient

Question 77

what is a symporter

Answer 77

2 molecules going through the same direction

Question 78

define neurons

Answer 78

specialized cells that use changes in membrane potential to transmit information

Question 79

what do dendrites do

Answer 79

receive incoming information

Question 80

what does the cell body do

Answer 80

contains the nucleus and metabolic centre of the cell

Question 81

what is the axon

Answer 81

a long extension for conducting outgoing impulses

Question 82

what is most important to generating resting membrane potential

Answer 82

K (potassium)

Question 83

does a nerve impulse retain intensity/strength with propagation

Answer 83

yes

Question 84

what are nodes of ranvier

Answer 84

where there are unwrapped gaps in myelinated axons

Question 85

where's the only site where action potentials can be generated

Answer 85

nodes of ranvier

Question 86

what is saltatory conduction

Answer 86

process by which action potentials are rapidly propagated along a myelinated axon by "jumping" from one node of Ranvier to the next