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MCAT Biochemistry > Biological Membrane > Flashcards

Biological Membrane Flashcards

Ch 8

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
concentration gradients
help to determine appropriate membrane transport mechanisms in cells
26
osmotic pressure
- colligative property - pressure applied to a pure solvent to prevent osmosis - used to express the concentration of the solution - "sucking" pressure in
27
passive transport
- does not require a transporter | - molecule is moving down its concentration gradient from an area of low concentration until equilibrium is achieved
28
simple diffusion
- 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
osmosis
-describes the diffusion of water across a selectively permeable membrane
30
facilitated diffusion
-uses transport proteins to move impermeable solutes across the cell membrane
31
active transport
requires energy in the form of ATP or an existing favorable ion gradient -may be primary or secondary depending on the energy source
32
primary active transport
uses ATP or another energy molecule to directly power the transport of molecules across a membrane -involves the use of a transmembrane ATPas
33
secondary active transport (coupled transport)
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
symport
when both particles flow the same direction across the membrane
35
antiport
when particles flow in the opposite direction
36
what is one example of primary active transport
in many tissues | primary active transport maintains the membrane potential of neurons in the nervous system
37
what is one example of secondary active transport
the kidneys usually driven by sodium reabsorb and secrete various solutes into and out of the filtrate
38
endocytosis
occurs when the cell membrane invaginate and engulfs material to bring it into the cell
39
exocytosis
occurs when secretory vesicles fuse with the membrane, releasing material from inside the cell to extracellular
40
pinocytosis
endocytosis of fluids and dissolved particles
41
phagocytosis
ingestion of large solids such as bacteria
42
what will initiate endocytosis
substrate binding to specific receptors embedded within the plasma membrane
43
what is an example of exocytosis
important in the nervous system and intercellular signaling | ex: exocytosis of neurotransmitters from synaptic vesicles
44
membrane potential
maintained by the sodium-potassium pump and leak channels
45
nerst equation
calculate the electrical potential created by one ion
46
goldman-hodgkin-katz voltage equation
calculate the resting potential of membrane eat physiological temperature
47
how does the mitochondrial membrane differ from the cell membrane
- outer mitochondrial membrane is highly permeable | - inner mitochondrial membrane does not contain cholesterol
48
the movement of any solute or water by diffusion or osmosis is dependent on what
only on the concentration gradient of that molecule and on membrane permeability
49
sphingolipids
- contain a hydrophilic region and two fatty hydrophobic tails ex: gangliosides, ceramide, sphingomyelin, cerebrosides
50
resting membrane potential depends on
- the differential distribution of ions across the membrane - active transport process - selective permeability of the phospholipid bilayer
51
what will contribute to membrane fluidity?
compounds that will lower the melting point or disrupt the crystal structure ex: cholesterol and unsaturated lipids
52
hypotonic
the concentration of soluce inside the cell is higher than the surround solution
53
hypertonic
a solution that is more concentrated than the cell | water will move out of the cell
54
isotonic
the solutions inside and outside are equimolar | -prevents the NET movement of particles

MCAT Biochemistry (8 decks)

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