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MCAT: Bio/ Biochem > Membranes > Flashcards

Membranes Flashcards

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1
Q

Name the membrane component: diffuses quickly and faces the same plane as the membrane

A

Phospholipids

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2
Q

Name the Membrane Component: diffuses slowly, and faces the same plane as the membrane.

A

Lipids & Proteins (think lipid rafts)

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3
Q

Name the Membrane Component: requires flipases to diffuse to the opposite side of a membrane

A

Phospholipids

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4
Q

What are Lipid Rafts made of?

A

cholesterol & proteins

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5
Q

What enzyme allows phospholipids and lipids to flip to face the other side of a membrane, and thus keep them diffusing easily and quickly to even out their concentration all over the membrane?

A

flipases

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6
Q

Why do phospholipids move to areas of the membrane where they’re least concentrated?

A

they’re diffusing

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7
Q

What region of the membrane is made of: proteins, carbohydrates, and phospholipid heads?

A

the hydrophilic membrane region

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8
Q

The ___ ____ membrane creates hydrophilic planes in and outside of cells.

A

fluid mosaic

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9
Q

The membrane is ___ ____.

A

Selectively Permeable

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10
Q

Name the two main types of fatty acids in membranes.

A

Saturated (each carbon holds as many hydrogens as possible) and Unsaturated (double or triple bonds take the place of where some hydrogens could be bonded to carbons)

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11
Q

Why are unsaturated fatty acids harder to “stack” and therefore less solid at room temperature?

A

their double bonds create a “kink” in the hydrocarbon chain that makes it harder to stack them

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12
Q

Adding saturated fatty acids make a membrane ___ fluid, while adding unsaturated fatty acids make the membrane ___ fluid.

A

less ; more

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13
Q

Which type of fatty acid would have a higher melting point?

A

saturated fatty acids

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14
Q

Fatty acids play a role in energy storage by being converted to ___ molecules.

A

triglyceride

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15
Q

What are triglyceride molecules made of?

A

3 fatty acids attached to a sugar (glycerol) backbone

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16
Q

How are triglycerides changed into glycerophospholipids for insertion into membranes?

A

a fatty acid chain is removed so a negatively charged phosphate group can be added

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17
Q

Name the parts of a phospholipid (technically called a glycerophospholipid!)?

A

2 fatty acids ; 1 glycerol ; 1 phosphate

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18
Q

What membrane lipid stabilizes the membrane in extreme heat, and gives it fluidity in the cold?

A

cholesterol

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19
Q

What are the three main types of fats found in the membrane?

A

Sphingolipids (1) ; Cholesterol (2) ; and Waxes (3)

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20
Q

____ ____ can activate or deactivate transporters for facilitated diffusion and active transport.

A

Membrane Receptors

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21
Q

Name 3 primary roles of cholesterol

A

steroid synthesis ; stabilizing the cell membrane ; increasing cell membrane fluidity

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22
Q

What lipids are derived from sphingosine?

A

sphingolipids

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23
Q

Phospholipids have __ less fatty acids than triacylglycerol.

A

1

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24
Q

What type of fat increases rigidity in plant cells membranes by stabilizing the hydrophobic region of the cells’ membranes?

A

waxes

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25
Q

What are waxes composed of?

A

a long fatty acid chain with a long chain ester

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26
Q

Name the 4 types of sphingolipids found in a cell membrane?

A

ceramides, sphingomyelin, cerebrosides, and gangliosides

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27
Q

Where do sphingolipids differ from phospholipids (region)?

A

in their hydrophilic region (they have an ester long chain instead of a sugar and phosphate)

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28
Q

What is the point of sphingolipids?

A

to yield biologically important (necessary) lipids: ceramides, sphingomyelin, cerebrosides, and gangliosides

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29
Q

Name the 4 major molecular components of the cell membrane.

A

Proteins ; Carbohydrates ; Membrane Receptors ; Cell-Cell Junctions

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30
Q

___ (a major membrane component) are important for forming biofilms and cell membrane communication and messaging.

A

carbohydrates

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31
Q

Name the 3 major types of membrane proteins.

A

Integral Proteins (Transmembrane & Embedded, I think?) and Peripheral (Membrane Associated)

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32
Q

Are transmembrane and embedded proteins both integral proteins?

A

idk ask

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33
Q

What type of membrane protein is Cytochrome C? (Hint: it’s vital for making ATP)

A

it’s a membrane-associated (peripheral) protein

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34
Q

What type of membrane protein is Cytochrome C Oxidase?

A

Membrane-Associated (peripheral) protein

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35
Q

What type of membrane protein goes through both ends of a membrane, and likely carries out tasks on both sides?

A

Transmembrane Proteins

36
Q

What type of membrane protein is an Aquaporin?

A

transmembrane protein

37
Q

What kind of membrane protein is the Sodium-K Pump?

A

transmembrane protein

38
Q

What kind of membrane proteins are chloride channels?

A

transmembrane proteins

39
Q

What kind of membrane protein is found on the outer edges of the membrane and is not associated with the membrane’s interior?

A

Membrane-Associated (Peripheral) Proteins

40
Q

What kind of membrane protein can associate with the interior or exterior of a cell membrane, but not both?

A

Embedded Proteins

41
Q

What kind of membrane protein are prostaglandin syntheses 1 and 2? (Hint: these make the proteins that cause smooth muscle contraction in the outer bilayer.)

A

Embedded Proteins

42
Q

Why are membrane carbohydrates generally hydrophilic?

A

they tend to have lots of oxygen molecules

43
Q

What types of carbohydrates tend to attach to proteins on extracellular surfaces?

A

membrane carbohydrates

44
Q

True / False: membrane carbohydrates form the cell coats found in biofilms, which compose plaques on our teeth?

A

True!

45
Q

True / False: Blood types come from surface carbohydrates!

A

true!

46
Q

___ (membrane component molecule) can be recognized by both the immune system and microbes.

A

True!

47
Q

Name the 3 types of cell-cell membrane junctions.

A

Gap Junctions (1) ; Desmosomes (2) ; and Tight Junctions (3)

48
Q

In __ diffusion, permeable (?) substances follow their concentration gradients across the membrane.

A

Simple Diffusion (a type of passive transport)

49
Q

In ___ diffusion, energy could be supplied by concentration gradients or entropy changes, but NOT ATP.

A

Simple Diffusion

50
Q

Can water move along it’s own concentration gradient?

A

yes

51
Q

What is Osmosis?

A

diffusion of water

52
Q

When the solute concentration is equal inside and outside of a cell, what kind of state is the cell in?

A

Isotonic

53
Q

True / False: If the environment around a cell is hypotonic, then that cell has a lower water concentration than it’s surroundings.

A

True!

54
Q

True / False: If the environment around a cell is hypertonic, then that cell has a higher water concentration than it’s surroundings.

A

True!

55
Q

____ ____ (pi) is the driving force behind osmosis.

A

Osmotic Pressure (Pi)

56
Q

Is Osmotic Pressure (Pi) a colligative property?

A

Yes

57
Q

What is the formula for Osmotic Pressure (Pi)?

A 
Pi  = iMRT 
i = Van't Hoff Factor (number of particles that dissociate into solution) because Osmotic Pressure is a colligative property 
M = Molarity
R = Ideal Gas Constant 
T = Temperature in Kelvin
58
Q

How can you quickly tell which solution of ions will have the highest or lowest ionic pressure?

A

the solution that dissociates into the most ions with the highest molarity will have the highest ionic pressure

59
Q

___ ___ uses membrane proteins to transport molecules that are otherwise impermeable to the membrane.

A

Facilitated Diffusion

60
Q

The ___ ___ of the cell membrane is too high for large / polar / charged molecules to pass through it freely so that a membrane protein is needed to help these across.

A

Energy Barrier

61
Q

What type of transport could move ions across a membrane without the input of energy?

A

Facilitated Diffusion ; sodium ions are impermeable, so you need a protein to transport them

62
Q

What is Simple Diffusion in reference to solute transport across membranes?

A

small, non polar molecules (like diatomic oxygen and carbon dioxide) are able to diffuse across the membrane according to their concentration gradients.

63
Q

In what type of transport does water move down it’s own concentration gradient across the membrane through specialized proteins? Hint: water always moves aganst the concentration gradient of solute.

A

Osmosis

64
Q

Water always moves (with / against) the concentration gradient of the solute.

A

AGAINST

65
Q

For ___ ___ the solute still moves across the membrane down it’s concentration gradient (no ATP is used), but needs to travel through a protein channel or a carrier protein because it is impermeable to the membrane.

A

Facilitated Diffusion

66
Q

Symport and Antiport are two processes associated with what kind of solute transport across membranes?

A

Secondary Active Transport

67
Q

What is Symport?

A

a type of secondary active transport in which the particles being moved are moving in the same direction across the membrane

68
Q

What is Antiport?

A

a type of secondary active transport in which the particles are moving in opposite directions across the membrane

69
Q

What are the two types of active transport?

A

Primary Active Transport: uses ATP
Secondary Active Transport: uses one molecule flowing down it’s concentration gradient to fuel transporting another molecule going against it’s concentration gradient

70
Q

EX: Na+ ions are flowing down their concentration gradient through a membrane protein, that uses this flow to move in an amino acid against it’s concentration gradient (in the opposite direction of the sodium ions). What type of transport is this?

A

Secondary Active Transport: the Na+ concentration gradient fuels the amino acid going against it’s own gradient.

71
Q

What is the driving energy source behind secondary active transport, since ATP cannot be used to fuel it?

A

the entropy change of allowing a solute to go with it’s concentration gradient (same driving force as facilitated diffusion and passive transport!)

72
Q

What is Primary Active Transport? What proteins does it typically use?

A

a type of active transport (moves solute against it’s concentration gradient) using ATP as it’s fuel ; typically done using transmembrane ATPases (the membranes that accomplish this are called this???)

73
Q

What is Secondary Active Transport?

A

a type of active transport (moves solute against it’s concentration gradient) using the energy from the entropy change of ANOTHER molecule flowing down (with) it’s concentration gradient

74
Q

What’s our quick and dirty way to see what solute has the most osmotic pressure?

A

look at it’s molarity and the number of ions it will dissociate into, that quantity (roughly multiplied) is directly proportional to osmotic pressure!!

75
Q

Osmosis is driven by ___ ___.

A

Osmotic Pressure

76
Q

While passive transport is driven by entropy change, what drives active transport? (in terms of energetic quantities)

A

enthalpy and temperature

77
Q

Facilitated Diffusion transports impermeable solute across membranes using what two proteins?

A

Protein Channels: can be open or closed in response to diverse signals
Carrier Proteins: work like revolving doors so that a solute enters from one side, and the protein shuts behind it before opening it’s other side to let the solute exit

78
Q

What is the Occluded State? Hint: it applies to Carrier Proteins.

A

the occluded state is when the protein is not open to either side. this state occurs in between letting the protein enter and letting it exit. Remember, revolving door.

79
Q

True / False: gong down one’s concentration gradient creates more disorder (S) and is therefore favorable.

A

hell yasss

80
Q

True / False: as temperature increases so does the rate of passive transport!

A

True

81
Q

Delta G is negative and positive for what kinds of transport, respectively?

A

delta G is negative for favorable processes, no energy input, spontaneous = Passive Transport

Delta G is positive for non spontaneous processes, need energy input, non spontaneous = Active Transport

82
Q

White blood cells eating pathogens is exocytosis or endocytosis? Specify.

A

endocytosis, specifically phagocytosis

83
Q

Neurotransmitter release at the synapse is an example of exocytosis or endocytosis?

A

Exocytosis

84
Q

There are tow main reasons that a cell would choose endo/exocytosis for transport. Name them

A

the particles being transported are:

  • too big to be transported by a protein
  • too big of a quantity to effectively transport any other way
85
Q

What is Pinocytosis?

A

the cell is getting fluids and dissolved compounds

86
Q

What is Phagocytosis?

A

pac man ; cells eats solids

87
Q

Do phagocycotis and pinocytosis use vesicles?

A

yes ; vesciles are necessary for this process

MCAT: Bio/ Biochem (7 decks)

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