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MCAT biochem > biological membranes > Flashcards

biological membranes Flashcards

(54 cards)

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1
Q

fluid mosaic model

A

describes the structure of the plasma membrane
-lipids and proteins diffuse freely
- lipid bilayer

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2
Q

lipid bilayer

A

two layers of phospholipids with polar heads facing environment and hydrophobic FA tails facing internal space

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3
Q

what force is PRIMARILY responsible for the formation of the lipid bilayer

A

hydrophobic interactions

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4
Q

other forces that contribute to the lipid bilayer

A

van der walls, hydrogen bonding, noncovalent

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5
Q

lipid rafts

A

held together by large amounts of cholesterol and high concentrations of sphingomyelins and diffuse in lipid bilayer to INCREASE FLUIDITY OF THE MEMBRANE and regulate signaling processes

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6
Q

cholesterol effect on memrbane at HIGH TEMPERATURES

A

decreases fluidity

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7
Q

cholesterol effect on membranes at LOW TEMPERATURES

A

increases fluidity

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8
Q

cholesterol effect on membranes at LOW TEMPERATURES

A

increases fluidity

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9
Q

purpose of unsaturated fatty acids in the plasma membrane

A

promote fluidity by preventing the tails from stacking as happens with saturated fatty acids

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10
Q

which direction in the membrane are phospholipids mobile

A

horizontal

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11
Q

flippases

A

allow phospholipids to shift from one face of the membrane to another (energetically costly)

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12
Q

3 main classes of lipids in the plasma membrane

A
  1. phospholipids –> major component
  2. sterols –> cholesterol
  3. glycolipids –> signalling
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13
Q

sphingosine

A

lipid with a sphingosone backbone instead of glycerol

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14
Q

which orientation are unsaturated fatty acids in the plasma membrane almost always?

A

cis

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15
Q

embedded proteins

A

proteins on the interior or exterior surface of the membrane but do not span it

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16
Q

transmembrane/ integral proteins

A

membrane spanning protein with a hydrophobic and hydrophilic region
major examples: GPCR and ion channels

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17
Q

peripheral proteins

A

attatched to integral protein or associate with peripheral region of the membrane

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18
Q

lipid anchored proteins

A

covalently bound to a small lipid molecule and anchored to protein within the membrane without the protein physically coming into contact with the membrane
- g proteins

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19
Q

majority of glycosylations are

A

O linked
- bound to a serine or a threonine

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20
Q

N glycosylations

A

bount to N on asparagine

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21
Q

o glycosylations

A

o linked to serine or threonine

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22
Q

example of glycoproteins

Study These Flashcards
A

ABO blood system

23
Q

liposomes

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A

lipid bilayers enclosing a spherical space , derived in lab

24
Q

how are liposomes formed in lab

Study These Flashcards
A
  1. suspend lipid in aqueous solution
  2. agitate mixture –> results in a vesicle
25
micelle
aggregate composed of a single layer of lipids with hydrophobic tails pointed toward the interior
26
micelles vs liposomes
liposomes are double membranes and micelles are single membranes
27
simple diffusion
nonpolar, small, uncharged particles can pass through membrane without facilitation down their concentration gradients ex: O2 and CO2 for gas/waste exchange , water, ethanol, urea
28
osmosis
special form of simple diffusion that applies specifically to solvents (water) - THE SOLVENT MOVES (WATER ) NOT THE SOLUTE Water moves from high to low concentration of solute via simple diffusion to equalize the solute concentrations
29
isotonic solution
extracellular space has the same solute concentration as the intracellular space
30
hypotonic solution
solution has a lower concentration of solute than the intracellular space - EC has more water than IC
31
hypertonic solution
solution has a higher concentration of solute than the cell
32
what happens when a cell is placed in a hypotonic solution
water rushes from solution into the cell and causes cell burst --> cytolysis
33
what happens when a cell is placed in a hypertonic solution
water moves from the cell into the EC and causes cell shrinkage - plasmolysis
34
when is equillibrium reached during osmosis
when hydrostatic pressure of water becomes large enough that it prevents more net osmosis from occuring --> pressure is osmotic pressure
35
osmotic pressure eqn
π = iMRT m is concetration of solute R is gas constant t is time in kelvin i is number of particles that result from a substance being placed into a solution (nacl would be 2, glucose would be 1 )
35
osmotic pressure eqn
π = iMRT m is concetration of solute R is gas constant t is time in kelvin i is number of particles that result from a substance being placed into a solution (nacl would be 2, glucose would be 1 )
36
what kind of property is osmotic pressure
colligative because it depends on solute concentration
37
facillitated diffusion
trasport from high to low concentration using a transport protein
38
aquaporins
specifically transport water
39
ion channels
facillitate diffusion of ions
40
active transport
energy is used (ATP) to force molecules against their concentration gradients
41
primary active tranport
energy is used to pump against concentration gradient
42
secondary active transport
energy to pump against graident is stored in an electrochemical gradient
43
example of primary transport enzymes
atpases: hydrolyze atp to pump things Na/K atpase
44
what does na/K atpase do
uses atp to pump 3 na out of cell and 2 k into cell
45
what kind of active transport is used in ETC
primary active transport redox reations harnessed via NADH e- and FADH2 and translocate H+
46
cotransport
secondary transport: relies on electrochemical differences to couple transport
47
antiporters
secondary transporters that transport 2 molecules in opposite directiosn. one is going with its gradient and the other isnt EX: sodium calcium transport
48
symport
both molecules are sent in the same direction, one is going in the direction of its gradient and the other is not SLGLT --> glucose and 2 na into cell
49
is endocytosis active or passive transport
active, requires energy to do pinocytosis and phagocytosis
50
early endosomes
pass molecules of interest onto late endosomes and recycle material back to the plasma membrane
51
late endosomes
pass material onto lysozome
52
lysozomes
final component of endocytic pathway - hydrolytic compartment of the cell - breaks down waste products - highly acidic (4.8).
53
constitutive exocytosis
preformed regularly by all cells to release material to the EC to deliver membrane proteins to the plasma membrane

MCAT biochem (11 decks)

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