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BMSC 207 > Module 2 > Flashcards

Module 2 Flashcards

1
Q

The main goal of a membrane is what?

A

Separating one compartment from another

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2
Q

List the four functions of the cell membrane.

A
  1. Physical isolation (separating ICF and ECF)
  2. Regulation of exchange with the environment
  3. Communication between cell and environment
  4. Structural support
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3
Q

In a typical cell membrane, we would expect to find roughly 55% of ____, 45% of ___, and small amounts of ___.

A

55% protein
45% lipids
small amounts of carbohydrates

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4
Q

Which of the following membranes would theoretically be the most metabolically active?

a) membrane with 35% protein comp.
b) membrane with 37% protein comp.
c) membrane with 47% protein comp.
d) membrane with 54% protein comp.

A

d) membrane with 54% protein comp.

Remember: the higher the protein=more metabolically active

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5
Q

What are the three types of lipids found in the cell membrane?

A
  1. Phospholipids
  2. Sphingolipids
  3. Cholesterol
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6
Q

What are some characteristics of phospholipids?

A

They can form bilayers, micelles, and liposomes
Amphipathic
Weak bonds
BULK OF LIPID IN CELL MEMBRANE

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7
Q

What is the structure of a phospholipid?

A

Glycerol backbone, fatty acid tail, polar head (phosphate + a molecule)

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8
Q

Which lipid is also known as lipid rafts?

A

Sphingolipids

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9
Q

What are some characteristics of sphingolipids?

A 
Can form lipid rafts 
Sphingosine backbone 
Fatty acid tail
Phosphate head
Larger than phospholipids, fewer in # 
Amphipathic 
Common to see lipid anchored proteins attached
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10
Q

What is the goal of cholesterol?

A

Increase viscosity (gives cell membrane strength and flexibility)

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11
Q

If a membrane has high cholesterol content, what would we expect to happen?

a) high viscosity, decreased permeability
b) high viscosity, increased permeability
c) low viscosity, decreased permeability
c) low viscosity, increased permeability

A

a) high viscosity, decreased permeability

as cholesterol content increases, permeability decreases

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12
Q

The current cell membrane model is known as the fluid mosaic model, describe this model.

A

Proteins dispersed throughout membrane
Extracellular surface has glycoproteins and glycolipids
Phospholipid heads face intracellular and extracellular compartments
Lipid tails form interior layer
Cholesterol inserted in lipid layer

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13
Q

Where would we expect to find integral membrane proteins?

A

integrated within the membrane

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14
Q

Where would we expect to find peripheral membrane proteins?

A

noncovalently bonded to integral proteins

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15
Q

Integral proteins are also called ___ proteins.

A

Transmembrane

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16
Q

Identify roles of integral proteins.

A 
membrane receptors
cell adhesion molecules 
transmembrane movement 
enzymes
mediators of intracellular signaling
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17
Q

Which lipid do lipid anchored proteins commonly associate with?

A

Sphingolipids

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18
Q

What is the goal of lipid rafts?

A

Cell signal transduction

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19
Q

Where would you expect to find carbohydrates on the cell membrane?

A

Extracellularly

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20
Q

Adipose tissue is 90% ___, skeletal muscle is 75% ___.

A

lipids, water

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21
Q

___ is the movement of water across a membrane in response to a solute concentration gradient.

a) tonicity
b) osmosis
c) active transport
d) osmolarity

A

b) osmosis

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22
Q

What is osmolarity?

A

The number of particles in solution

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23
Q

1OsM of glucose and 1OsM of NaCl would be ___.

a) isotonic
b) isosmotic
c) hypertonic
d) hyperosmotic

A

b) isosmotic (idential osmolarities)

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24
Q
  1. 8OsM of glucose would be ___ to 1.2OsM of NaCl.
    a) hyperosmotic
    b) isosmotic
    c) hyposmotic
    d) hypertonic
A

a) hyperosmotic

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25
Q
  1. 2OsM of NaCl is ___ to 1.8OsM of glucose.
    a) hyperosmotic
    b) isosmotic
    c) hyposmotic
    d) hypotonic
A

c) hyposmotic

26
Q

What is tonicity?

A

How a solution would affect cell volume if a cell were placed in the solution

27
Q

What are the three tonicity terms?

A

isotonic, hypotonic, hypertonic

28
Q

What are the units for tonicity?

a) mg/g
b) mol
c) mOsm/L
d) it has no units

A

d) it has no units

29
Q

What is simple diffusion?

A

The movement of molecules from an area of higher concentration to an area of lower concentration, typically used for small uncharged, lipophilic molecules (O2, CO2, NH3, lipids, steroids)

30
Q

What are some circumstances that would make diffusion faster?

A

Higher concentration gradient
Over shorter distance
At higher temperatures
For smaller molecules

31
Q

Simple diffusion across a membrane depends on what?

A 
Concentration gradient across membrane 
Membrane surface areas 
Thickness of membrane 
Lipid solubility 
Composition of lipid layer
32
Q

What does membrane permeability depend on?

A

The molecules lipid solubility
The molecules size
The lipid composition of the membrane

33
Q

What is a channel protein?

A

Membrane spanning protein subunits that create a cluster of cylinders with a pore through the center

34
Q

What determines what passes through a channel protein?

A

Size of the pore and charge at the center of the pore

35
Q

Leak channels are typically in a ___ state, Gated channels are typically in a ___ state.

A

open, closed

36
Q

How do carrier proteins move molecules?

A

They change their conformation

37
Q

Contrast uniport carriers, symport carriers, and antiport carriers

A

Uniport carriers: transport only one kind of substrate
Symport carriers: move two or more substrates in the same direction
Antiport carriers: move substrates in opposite directions

38
Q

What is active transport?

A

Moving molecules against their concentration gradient, uses carrier proteins, support a state of disequilibrium

39
Q

Contrast between primary and secondary active transport.

A

Primary: energy to move molecules comes from ATPase
Secondary: uses the potential energy of one molecule to push another molecule

40
Q

What is the result of the N+/K+ ATPase?

A

3 Na+ released into ECF, 2 K+ released into ICF

41
Q

The sodium glucose transporter (SGLT) is an example of ___ transport.

A

Secondary active transport

42
Q

A carrier having a preference for a certain substrate over another substrate is known as ___.

A

Competition

43
Q

If a transporter will move molecule A but not molecule B, this is called ____.

A

Specificity

44
Q

Specificity, competition, and saturation are all key properties of both active and passive _____.

A

Carrier mediated transport

45
Q

If a macromolecule cannot fit through a carrier or channel, what type of transport is used?

a) Vesicular
b) Passive
c) Active
d) Epithelial

A

a) vesicular

46
Q

Bringing a molecule into the cell via vesicle is known as ____.

A

endocytosis

47
Q

What are the two types of endocytosis?

A 
Non selective (pinocytosis) 
Selective (receptor mediated)
48
Q

Typically, what will be seen brought into the cell via endocytosis?

A

Small proteins, antibodies, hormones, growth factors

49
Q

Transport out of the cell is known as ___.

A

Exocytosis

50
Q

Which mineral can regulate exocytosis?

a) Na+
b) Ca2+
c) K+
d) Fe

A

b) Ca2+

51
Q

The apical surface is:

a) facing lumen
b) facing away from lumen
c) in contact with ECF
d) in contact with ICF

A

a) facing lumen

52
Q

Which compartment does the basolateral membrane come in contact with?

A

ECF

53
Q

What are the three types of epithelial transport?

A

Paracellular
Transcellular
Transcytosis

54
Q

The ECF has a slight excess of ___, the ICF has a slight excess of ___.

A

cations, anions

55
Q

What is membrane potential?

A

The electrical disequilibrium that exists between the ECF and ICF.

56
Q

The membrane potential of a cell when it is not active is called what?

A

Resting membrane potential

57
Q

What determines the membrane potential?

A

Na-K ATPase

58
Q

What is the resting membrane potential?

A

-70mV

59
Q

What are the two factors that influence a cell’s membrane potential?

A

Concentration gradients of different ions across the membrane
Permeability of the membrane to those ions

60
Q

What is depolarization?

A

Membrane potential becomes less negative than the resting potential

61
Q

What is hyperpolarization?

A

Membrane potential becomes more negative

BMSC 207 (6 decks)

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