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MCAT Biochemistry > Biological Membrane > Flashcards

Biological Membrane Flashcards

Ch 8

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MCAT flashcards
1
Q

fluid mosaic model

A

accounts for the presence of lipids, proteins, and carbohydrates in a dynamic, semisolid plasma membrane that surrounds the cell

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2
Q

plasma membrane contains what

A

contains proteins embedded within the phospholipid bilayer

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3
Q

fatty acids

A

carboxylic acids that contain a hydrocarbon chain and a terminal carboxyl group
-can be saturated or unsaturated

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4
Q

triacylglycerols (triglycerides)

A

storage lipids involved in human metabolic processes

-contain three fatty acid chains esterified to a glycerol molecule

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5
Q

unsaturated fatty acids

A
  • regarded as “healthier” fats

- have more double bonds and exist in liquid form at room temperature

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6
Q

what are two important essential fatty acids for humans

A

alpha linolenic acid

linolenic acid

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7
Q

saturated fatty acids

A

main components of animal fats and tend to exist as solids at room temperature
-when incorporated into phospholipid membranes, saturated fatty acids decrease the overall membrane fluidity

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8
Q

glyercerophospholipid structure

A
  • also known as a phospholipid
  • by substituting one of the fatty acid chains of triacylglycerol with a phosphate group
  • polar head, nonpolar tails
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9
Q

phospholipids can assemble into

A

-micelles (small monolayer vesicles)
-liposomes (bilayered vesicles)
due to hydrophobic interactions

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10
Q

phospholipid function

A
  • membrane synthesis and can produce a hydrophilic surface layer on lipoproteins
  • primary component of cell membranes
  • second messengers in signal transduction
  • attachment point for water-soluble groups
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11
Q

waxes

A

class of lipids that are extremely hydrophobic and are sometimes found in the cell membranes of plants

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12
Q

transmembrane proteins

A

pass completely through the lipid bilayer and function as receptors or channels
-have both extracellular and intracellular domain

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13
Q

embedded proteins

A

associated with only the interior or exterior surface of the cell
involved in cellular communication

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14
Q

desmosomes

A

bind adjacent cells by anchoring to their cytoskeleton

-found at the interface between two layers of epithelial tissue

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15
Q

hemidesmosomes

A

attach to epithelial cells to underlying structures, especially the basement membrane

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16
Q

flippases

A

specific membrane proteins that maintain the bidirectional transport of lipids between the layers of the phospholipid bilayer in cells

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17
Q

cholesterol

A

present in large amount and contributes to membrane fluidity and stability

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18
Q

what are the three types of proteins within the cell membrane

A

transmembrane proteins
embedded proteins
membrane associated proteins

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19
Q

membrane associated proteins

A

as as recognition molecules or enzymes

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20
Q

what is carbohydrates function in the membrane?

A 
form a protective glycoprotein coat 
function in cell recognition
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21
Q

extracellular ligands function in the membrane

A

bind to membrane receptors, which function as channels or enzymes in second messenger pathways

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22
Q

cell-cell junctions function in the membrane

A

regulate transport intracellularly and intercellularly

23
Q

gap junctions

A

allow for rapid exchange of ions and other small molecules between adjacent cells

24
Q

tight junctions

A

prevent paracellular transport but do not provide intercellular transport

25
Q

concentration gradients

A

help to determine appropriate membrane transport mechanisms in cells

26
Q

osmotic pressure

A
  • colligative property
  • pressure applied to a pure solvent to prevent osmosis
  • used to express the concentration of the solution
  • “sucking” pressure in
27
Q

passive transport

A
  • does not require a transporter

- molecule is moving down its concentration gradient from an area of low concentration until equilibrium is achieved

28
Q

simple diffusion

A
  • does not require a transporter
  • small, nonpolar molecules passively move from an area of high concentration to an area of low concentration until equilibrium is achieved
29
Q

osmosis

A

-describes the diffusion of water across a selectively permeable membrane

30
Q

facilitated diffusion

A

-uses transport proteins to move impermeable solutes across the cell membrane

31
Q

active transport

A

requires energy in the form of ATP or an existing favorable ion gradient
-may be primary or secondary depending on the energy source

32
Q

primary active transport

A

uses ATP or another energy molecule to directly power the transport of molecules across a membrane
-involves the use of a transmembrane ATPas

33
Q

secondary active transport (coupled transport)

A

uses energy to transport particles across the membrane
-gets energy from the energy released by one particle going down its electrochemical gradient to drive a different particle up its gradient

34
Q

symport

A

when both particles flow the same direction across the membrane

35
Q

antiport

A

when particles flow in the opposite direction

36
Q

what is one example of primary active transport

A

in many tissues

primary active transport maintains the membrane potential of neurons in the nervous system

37
Q

what is one example of secondary active transport

A

the kidneys
usually driven by sodium
reabsorb and secrete various solutes into and out of the filtrate

38
Q

endocytosis

A

occurs when the cell membrane invaginate and engulfs material to bring it into the cell

39
Q

exocytosis

A

occurs when secretory vesicles fuse with the membrane, releasing material from inside the cell to extracellular

40
Q

pinocytosis

A

endocytosis of fluids and dissolved particles

41
Q

phagocytosis

A

ingestion of large solids such as bacteria

42
Q

what will initiate endocytosis

A

substrate binding to specific receptors embedded within the plasma membrane

43
Q

what is an example of exocytosis

A

important in the nervous system and intercellular signaling

ex: exocytosis of neurotransmitters from synaptic vesicles

44
Q

membrane potential

A

maintained by the sodium-potassium pump and leak channels

45
Q

nerst equation

A

calculate the electrical potential created by one ion

46
Q

goldman-hodgkin-katz voltage equation

A

calculate the resting potential of membrane eat physiological temperature

47
Q

how does the mitochondrial membrane differ from the cell membrane

A
  • outer mitochondrial membrane is highly permeable

- inner mitochondrial membrane does not contain cholesterol

48
Q

the movement of any solute or water by diffusion or osmosis is dependent on what

A

only on the concentration gradient of that molecule and on membrane permeability

49
Q

sphingolipids

A
  • contain a hydrophilic region and two fatty hydrophobic tails
    ex: gangliosides, ceramide, sphingomyelin, cerebrosides
50
Q

resting membrane potential depends on

A
  • the differential distribution of ions across the membrane
  • active transport process
  • selective permeability of the phospholipid bilayer
51
Q

what will contribute to membrane fluidity?

A

compounds that will lower the melting point or disrupt the crystal structure
ex: cholesterol and unsaturated lipids

52
Q

hypotonic

A

the concentration of soluce inside the cell is higher than the surround solution

53
Q

hypertonic

A

a solution that is more concentrated than the cell

water will move out of the cell

54
Q

isotonic

A

the solutions inside and outside are equimolar

-prevents the NET movement of particles

MCAT Biochemistry (8 decks)

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