Cell Membranes & Transport Thru Review

Question 1

what are the 3 categories of cell membrane lipids

Answer 1

phospholipids
glycolipids
cholesterol

Question 2

examples of phospholipids

Answer 2

glycerophospholipid

sphingomyelin

Question 3

glycerophospholipid structure

Answer 3

2 fatty acids connected to glycerol

pi connected to glycerol

alcohol attached to pi

Question 4

glycerophospholipid – common alcohols attached

Answer 4

amino acid serine
sugar alcohols
–inositol, glycerol

organic alcohols
–ethanolamine, choline

Question 5

sphingomyelin

Answer 5

fatty acid attached to an amine

found in myelin sheaths

Question 6

examples of glycolipids

Answer 6

they contain sugars
glycosphingolipid
glycoglycerolipids

Question 7

glycosphingolipids

Answer 7

found in mammals

fatty acid + glucose or galactose

Question 8

glycoglycerolipids

Answer 8

found in plants/bacteria

carb attached to glycerol w/ 2 fatty acid chains

Question 9

cholesterol

Answer 9

or sterols
give rigidity to memb

OH connected to 4 carbon rings
fatty acid chain on other end of rings

OH is polar head, the rest in nonpolar

Question 10

width of bilayer

Answer 10

60 - 100 A

hydrophobic 30A

Question 11

carbohydrate side chains of glycoproteins and the cell membrane

Answer 11

carb side chains always extend into EC matrix

Question 12

list membrane protein functions

Answer 12

• -receive signals
• -transmit signals to cytosol or other cells
• -allow passage
• -help determine memb thickness and rigidity

Question 13

membrane fluidity – lipids, bacteria, humans

Answer 13

1. are 2D fluids and only allow lat mvt
2. memb rigidity is determined by fa composition
3. memb rigidity is determined by cholesterol content

Question 14

define passive transport

Answer 14

no nrg needed

solute travels down conc gradient

Question 15

define active transport

Answer 15

coupled w/ ATP hydrolysis

solute travels up conc gradient

Question 16

what are the 3 general modes of transport

Answer 16

antiporter
symporter
uniporter

Question 17

what are the 3 general categories of transporters?

Answer 17

pumps
---primary active transport
carriers
---traverse memb w/o needing nrg
channels
---passive transport

Question 18

examples of primary active transport - pumps

Answer 18

p type pump
ABC transporter
Na/K pump
SERA

Question 19

p type pump

Answer 19

phosphorylates itself

Question 20

SERA pump

Answer 20

moves Ca from SR into cytosol of muscle

uses ATP to cause conformational change to release Ca to cytosol

Question 21

Na/K pump

Answer 21

2 Na moved to EC
3K moved to IC

uses ATP

Question 22

application of primary active transport - Na/K pump

Answer 22

digitalis and ouabain drugs
lock pump in E2 state
Na trapped IC

excess Na removed by Ca/Na pump
excess Ca leads to heart contraction

Question 23

ABC transporters and examples

Answer 23

ATP binding cassette to move small molecules

ex. MDR protein and Msba

E1 = open to EC
2 ATP used to invert to E2

Question 24

define secondary active transport

Answer 24

–using the gradient caused by primary active transport going against a gradient

–a passive channel/carrier can move ions down the gradient

Question 25

all secondary active transporters are _______.

Answer 25

symporters

Question 26

examples of secondary active transport

Answer 26

Na-glucose co-transporter

lactose permease

Question 27

Na-glucose transport

Answer 27

from lumen of intestines thru apical domain into cell

lose Na thru basal domain Na/K pump and glucose to blood via Glut-2

powered by primary Na/K pump

Question 28

lactose permease

Answer 28

1. an empty carrier
2. H+ binds and affinity for lactose increase
3. lactose binds-evert to E2 open to EC
4. lactose released
5. deprotonation and invert to E1 open to IC

Question 29

list some factors that affect rate of simple diffusion

Answer 29

1. conc gradient
2. size
3. shape
4. temp
5. density of solvent
6. solubility of solute
7. distance

Question 30

list types of ion channels

Answer 30

voltage gated
ligand gated
non-gated
mechanically gated

Question 31

how do ion channels choose what goes thru?

Answer 31

selectivity filter
ex. K+ channels are non-gated but only K gets thru

electrostatic repulsion only lets K+ thru

Question 32

neuromuscular transmission – describe the pathway of channels

Answer 32

1. depolarization opens v gated Ca channels
2. exocytosed ACH opens ligand gated Na channels
3. local potential opens adjacent v gated Na channels
4. depolarization spreads and Ca channels continue to open
5. coupled Ca release channels embedded in SR open

Question 33

gap junctions

Answer 33

facilitated diffusion

a hole between neighbor cells

allows the sharing of cytoplasm w/ no selectivity filter

Question 34

aquaporins

Answer 34

always open
only polar water can pass

have Asn residues that align water

water moves along using H bonds