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VP Cell Physiology > Test 2 Cell Membrane > Flashcards

Test 2 Cell Membrane Flashcards

1
Q

What is the purpose of the cell membrane?

A
  1. Separation of antiparallel processes (avoiding competition).
  2. Separation of similar reactions for different purposes.
  3. Energy efficiency.
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2
Q

What is the purpose of the plasma membrane?

A

Regulate movement in/out of cell. Facilitates electrical signaling between cells. Defines boundaries of organelles and separates complex chemical reactions.

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3
Q

What is the purpose of proteins within the cell membrane?

A

Mediate transport and catalysis of reactions. Structural links for connecting the cytoskeleton to the extracellular matrix or an adjacent cell. Serve as receptors to detect and transduce signals.

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4
Q

What are the components of a biological membrane?

A

Lipids, proteins, carbohydrates, water, divalent cations, and cholesterin.

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5
Q

What (3) main lipids make up the plasma membrane?

A

Phospholipids, sphingolipids, and cholesterol.

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6
Q

What are the (4) major phospholipids found in mammalian plasma membranes?

A

Phosphoglycerides: Phosphatidylethanolamine, Phosphatidylserine, Phosphatidylcholine.
Sphingolipids: Sphingomyelin.

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7
Q

What do phospholipids do in an aqueous environment?

A

Spontaneously form micelles or bilayers.

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8
Q

What type of molecules can pass through the cell membrane?

A

Uncharged small molecules.

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9
Q

What is a RBC’s cell membrane covered in?

A

Membrane proteins.

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10
Q

What technique is used to view both layers of the lipid bilayer?

A

Freeze Fracturing.

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11
Q

What are the typical parts of a phospholipid molecule?

A

Polar head group and nonpolar tail.

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12
Q

What are the most relevant phospholipids in the membrane?

A

Phosphatidylethanolamine, phosphatidylcholine, sphingomyelin, and phosphatidylserine.

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13
Q

How can lipids move within the lipid bilayer?

A

Transverse diffusion (flip-flop) and lateral diffusion.

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14
Q

What is phase transition?

A

Change of a lipid bilayer from a liquid state to a more solid state.

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15
Q

How do lipids act at low temperatures?

A

Show less movement, creating a more rigid membrane.

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16
Q

How do lipids act at higher temperatures?

A

Plasma membrane becomes more fluid.

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17
Q

What do cis double bonds do to the membrane?

A

Keeping lipids from packing too tightly, and keeps it from freezing.

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18
Q

What does cholesterol do for a membrane?

A

Keeps the membrane in a fluid state.

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19
Q

What is the extracellular matrix?

A

Complex intricate network of macromolecules that surrounds/contains the cells.

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20
Q

Where are macromolecules in the ECM produced?

A

Locally by cells in the matrix.

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21
Q

What are the major classes of macromolecules within the ECM?

A

Glycosaminoglycans (proteoglycans), fibrous proteins (like collagen), and non-collagen fibrous proteins (glycoproteins).

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22
Q

What is the structure of collagen?

A

Long, fibrous, triple-stranded helical proteins. Rich in glycosylated proline and glycine.

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23
Q

Where can type I collagen be found?

A

Bone, skin, tendons, ligaments, cornea, and internal organs. It accounts for 90% of body collagen.

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24
Q

What type of collagen is found in skin, blood vessels, and internal organs?

A

Type III.

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25
Q

What gives tissues elasticity?

A

Elastin.

26
Q

What is the structure of elastin?

A

Hydrophobic protein rich in un-glycosylated proline and glycine.

27
Q

What is the purpose of glycoproteins within the ECM?

A

They have multiple domains with specific binding sites for other matrix macromolecules and for receptors of the cell surface.

28
Q

What helps organize the ECM and cells attach to it?

A

Fibronectin.

29
Q

What is the basal lamina (basement membrane)?

A

Specialized form of the ECM that lies beneath epithelial cells, and contains collagen.

30
Q

What is found within the extracellular matrix?

A

Collagen, fibronectin, and proteoglycans.

31
Q

What makes collagen?

A

Fibroblasts.

32
Q

What is laminin?

A

Primary protein that makes up the basal lamina and is composed of (3) polypeptide chains and is held together by disulfide bonds.

33
Q

What are integrins?

A

Transmembrane proteins that act as matrix receptors. They link the cytoskeleton with the ECM.

34
Q

Which side of the lipid bilayer is hydrophobic?

A

Interior layer.

35
Q

What is the purpose of transport proteins within the membrane?

A

Transfer specific water soluble molecules across the plasma membrane.

36
Q

T/F: Because the interior of the lipid bilayer is hydrophobic, the passage of most polar molecules is restricted.

A

True

37
Q

Which ion is in high concentration extracellularly?

A

Sodium, chloride, calcium and magnesium.

38
Q

What is passive transport?

A

Down a concentration gradient.

39
Q

What is active transport?

A

Requires energy and is always mediated by transporters, it moves solutes against its concentration gradient.

40
Q

Describe passive diffusion.

A

No membrane proteins are involved and direction of transport is determined by relative concentrations. Solute dissolves in the phospholipid bilayer.

41
Q

Describe facilitated diffusion.

A

No external energy source provided and direction of transport is determined by their concentration gradients. Passage is mediated by proteins, and the solute does NOT dissolve within the lipid bilayer.

42
Q

Carrier-Mediated vs Simple Diffusion.

A

Diffusion/channel mediated transport is directly proportional to the solute concentration. Carrier-mediated transport will hit Vmax depending on saturation.

43
Q

What is active transport?

A

Uses energy or gradient generated by another active transporter.

44
Q

What are the types of active transporters?

A

Uniporters, Symporters, and Antiporters.

45
Q

What is a uniporter?

A

Passive transport of only one molecule.

46
Q

What is a symporter?

A

Coupled transporters of (2) molecules in the same direction (co-transporters).

47
Q

What is an antiporter?

A

Transport of a second molecule in the opposite direction.

48
Q

What drives secondary active transporters?

A

By a gradient generated by a primary active transporter.

49
Q

What drives tertiary active transporters?

A

By a gradient generated by a secondary active transporter.

50
Q

What drives primary active transporters?

A

By ATP, ATP is hydrolyzed to ADP and Pi.

51
Q

What are the classes of ATP-driven pumps?

A

P-type, F-type, V-type pumps and ABC transporters.

52
Q

How to P-type pumps work?

A

They phosphorylate themselves during the pumping cycle.

53
Q

How do F-type and V-type pumps work?

A

Turbine-like proteins that function as ATPases and ATP synthases.

54
Q

What is an example of a primary active transporter?

A

Na+/K+ ATPase. 3Na+ molecules pumped out while 2 K+ are pumped in.

55
Q

What is an example of a secondary active symporter?

A

Sodium Glucose Transporter (SGLT). 1 Glucose and 2 Na+ are transported into the cell.

56
Q

What is an example of a secondary active antiporter?

A

Sodium/Calcium Exchanger (NCX): Na+ into the cell and Ca2+ outside of the cell. Sodium/Proton Exchanger (NHE): Na+ into the cell and H+ outside of the cell.

57
Q

What is an example of a tertiary active transporter?

A

Proton/peptide symporter. Peptides and H+ transported into the cell.

58
Q

What are aquaporins?

A

Specific water channels within the plasma membrane of cells making water movement more efficient.

59
Q

What is the Km value of an enzyme?

A

Affinity for substrate.

60
Q

Which enzyme can work at a very basic pH?

A

Alkaline phosphatase.

VP Cell Physiology (5 decks)

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