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CMB (Lecture) > Unit lll - Membrane Transport and Functions > Flashcards

Unit lll - Membrane Transport and Functions Flashcards

1
Q

Cell membrane controls what enters and exits the cell to maintain an internal balance called _______.

A

homeostasis

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2
Q

It is a double layer of phospholipids

A

lipid bilayer

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3
Q

Lipid bilayer contains almost proteins called ________

A

membrane proteins

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4
Q

They predicted the bilayer membrane structure as early as 1925.

A

Gorter and Grendel

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5
Q

Structure of Cell Membrane/Lipid Bilayer

A

a. Phosphate head is polar • (water loving)
b. Fatty acid tails non-polar • (water fearing)
c. Proteins embedded in membrane

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6
Q

• Allows some molecules in and keeps other molecules out.
• The structure helps it be selective!

A

Selectively permeable

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7
Q

In 1972, _______ and _______ proposed that the membrane is a mosaic of proteins dispersed within the bilayer, with only the _________ exposed to water.

A

S. J. Singer and G. Nicolson
hydrophilic regions

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8
Q

Seymour Jonathan Singer and Garth Nicolson proposed the ________

A

Fluid Mosaic Model

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9
Q

• Lateral movements occurs ________
• Flip-flopping across the membrane is rare (_______)

A

10⁷ times per second

Once per month

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10
Q

• Most of the ____, and some _____, drift laterally.
• Rarely does a molecule flip-flop transversely across the membrane

A

lipids
proteins

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11
Q

The fluidity of membranes

A

a. Unsaturated vs Saturated Hydrocarbon chains
b. Cholesterol within the animal cell membrane

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12
Q

Variations in lipid composition of cell membranes of many species appear to be ____________

A

adaptations to specific environmental conditions

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13
Q

Types of Membrane Proteins

A

Integral Proteins
Pumps
Channel Proteins
Carrier Proteins
Enzyme Protein
Receptor Proteins

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14
Q

70% of Cell membrane proteins part and parcel of membrane structure

A

Integral Proteins

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15
Q

They transfer substances against Concentration / Electrical gradients

A

Pumps

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16
Q

Opened and closed by gates

A

Channel Proteins

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17
Q

Involved in transport of substances

A

Carrier Proteins

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18
Q

Proteins takes place in membrane reaction

A

Enzyme Proteins

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19
Q

They bear appropriate sites for recognition of Specific Ligands.

A

Receptor Proteins

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20
Q

Proteins that penetrate the hydrophobic core

A

Integral proteins

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21
Q

Proteins that are bound to the surface of the membrane

A

Peripheral proteins

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22
Q

Functions of Cell Membrane

A

a. Transport
b. Enzymatic activity
c. Signal transduction
d. Cell - cell recognize
e. Intercellular joining
f. Attachment to the cytoskeleton and extracellular matrix (ECM)

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23
Q

Cells recognize each other by binding to ________, often containing carbohydrates, on the extracellular surface of the plasma membrane.

A

surface molecules

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24
Q

Membrane carbohydrates may be covalently bonded to lipids (forming __________) or more commonly to proteins (forming __________)

A

glycolipids
glycoproteins

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25
Q

HIV can infect a cell that has ____ on its surface, as in most people.

HIV cannot infect a cell lacking _____ on its surface, as in resistant individuals

A

CCR5

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26
Q

can dissolve in the lipid bilayer and pass through the membrane rapidly, such as hydrocarbons

A

Hydrophobic (nonpolar) molecules

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27
Q

do not cross the membrane easily, such as sugar

A

Hydrophilic (polar) molecules

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28
Q

Allow passage of hydrophilic substances across the membrane

A

Transport proteins

29
Q

Have a hydrophilic channel that certain molecules or ions can use as a tunnel

A

Channel proteins

30
Q

Channel proteins called ________ facilitate the passage of water

A

aquaporins

31
Q

Bind to molecules and change shape to shuttle them across the membrane

A

Carrier proteins

32
Q

Two types of transport mechanism

A

Active process
Passive process

33
Q

Types of Active process

A

Primary transport
Secondary transport

34
Q

Types of passive process

A

Simple diffusion
Facilitated diffusion
Osmosis
Bulk flow filtration

35
Q

Substances diffuse down their _____________, the region along which the density of a chemical substance increases or decreases.

A

concentration gradient

36
Q

The diffusion of a substance across a biological membrane is _________ because no energy is expended by the cell to make it happen.

A

passive transport

37
Q

Factors that influence diffusion rates

A

• Distance
• Molecular size
• Temperature
• Steepness of Concentration Gradient
• Membrane of Surface Area

38
Q

______________
___________ can enter cells easily because they diffuse through the lipid portion of the membrane

A

Simple diffusion
Lipophilic substances

39
Q

Membrane channels are transmembrane proteins

Used by ions, very small water-soluble compounds

Much more complex than simple diffusion.

A

Channel-Mediated Diffusion

40
Q

Diffusion Through the Plasma Membrane (3)

A

• Simple diffusion
• Channel-mediated facilitated diffusion
• Carrier-mediated facilitated diffusion

41
Q

It is the diffusion of water across a selectively permeable membrane

A

Osmosis

42
Q

Water Balance of Cells Without Walls

A

Tonicity
Isotonic solution
Hypertonic solution
Hypotonic solution

43
Q

is the ability of a surrounding solution to cause a cell to gain or lose water

A

Tonicity

44
Q

Solute concentration is the same as that inside the cell; no net water movement across the plasma membrane

A

Isotonic solution

45
Q

Solute concentration is greater than that inside the cell; cell loses water

A

Hypertonic solution

46
Q

Solute concentration is less than that inside the cell; cell gains water

A

Hypotonic solution

47
Q

Effects of tonicity in animals and plants

A

a) animal cell (lysed, normal, shriveled)

b) plant cell (turgid, flaccid, plasmolyzed)

48
Q

• A plant cell in a hypotonic solution swells until the wall opposes uptake; the cell is now ______ (firm)

A

turgid

49
Q

• If a plant cell and its surroundings are isotonic, there is no net movement of water into the cell; the cell becomes ______ (limp), and the plant may wilt

A

Flaccid

50
Q

In a hypertonic environment, plant cells lose water; eventually, the membrane pulls away from the wall, a usually lethal effect called ________.

A

plasmolysis

51
Q

In __________, transport proteins speed the passive movement of molecules across the plasma membrane

A

facilitated diffusion

52
Q

moves substances against their concentration gradients

A

Active transport

53
Q

allows cells to maintain concentration gradients that differ from their surroundings

A

Active transport

54
Q

The __________ is one type of active transport system.

A

sodium-potassium pump

55
Q

Process of active transport

A
  1. Insert Na
  2. Insert ATP
  3. Release Na
  4. Attach K
  5. Attach ATP
  6. Attach K
56
Q

is the voltage difference across a membrane

A

Membrane potential

57
Q

is created by differences in the distribution of positive and negative ions across a membrane

A

Voltage

58
Q

Two combined forces, collectively called the ___________, drive the diffusion of ions across a membrane

A

electrochemical gradient

59
Q

the ion’s concentration gradient

A

Chemical force

60
Q

the effect of the membrane potential on the ion’s movement

A

electrical force

61
Q

It is a transport protein that generates voltage across a membrane.

A

Electrogenic pump

62
Q

The main electrogenic pump of plants, fungi, and bacteria is a ________.

A

proton pump

63
Q

It maintains membrane potential

A

Ion pumps

64
Q

occurs when active transport of a solute indirectly drives transport of other solutes.

A

Cotransport

65
Q

Bulk transport across the plasma membrane occurs by _______ and _______

A

exocytosis
endocytosis

66
Q

• Small molecules and water enter or leave the cell through the ______ or via _________
• Large molecules, such as polysaccharides and proteins, cross the membrane in _____ via ______
• Bulk transport requires energy

A

• lipid bilayer or via transport proteins
• bulk via vesicles

67
Q

In _______, transport vesicles migrate to the membrane, fuse with it, and release their contents • Many secretory cells use ________ to export their products

A

exocytosis

68
Q

In _______, the cell takes in macromolecules by forming vesicles from the plasma membrane

A

endocytosis

CMB (Lecture) (5 decks)

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