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BIOL 385 > CH 5 — membrane dynamics > Flashcards

CH 5 — membrane dynamics Flashcards

1
Q

What are the 4 types of membrane proteins based on function?

A
  1. membrane transport
  2. structural proteins
  3. membrane enzymes
  4. membrane receptors
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2
Q

What are the 2 types of membrane transport?

A
  1. carrier proteins: active (primary/secondary), or passive
  2. channel proteins (open/leaky, or gated —> mechanically, voltage, chemically/ligand)
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3
Q

What types of membrane transport uses ATP?

A

active carrier proteins (primary uses ATP directly, secondary not directly)

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4
Q

What types of membrane transport does not use ATP?

A
  • passive carrier proteins
  • facilitated diffusion
  • open/leaky channel proteins
  • gated channel proteins
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5
Q

What are structural proteins used for?

A

used to anchor cell junctions and cytoskeleton

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6
Q

What are membrane enzymes used for?

A

metabolism and signal transfer

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7
Q

What are membrane receptors used for?

A
  1. receptor mediated endocytosis
  2. signal transfer
  3. open and close chemically gated channels
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8
Q

What fills channel proteins?

A

they have a water-filed pore in the center

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9
Q

What determines what ions pass through a channel protein?

A

the structure (they are made of multiple protein subunits that assemble in the membrane

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10
Q

What part of the channel allows ions to pass through?

A

the hydrophilic amino acids that line the channel

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11
Q

What are the types of carrier proteins that regulate the number of molecules transported?

A
  • unimportant carriers: move 1 molecule
  • cotransporters: move more than one type of molecule (at different times) (can NOT move more than 3)
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12
Q

What are symport carriers?

A
  • carrier proteins
  • all the things it moves go in the same direction
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13
Q

What are antiport carriers?

A
  • carrier proteins
  • things go in opposite direction (one molecule to ECF, other to ICF)
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14
Q

What are GLUT transporters?

A
  • helps with passive transport (does NOT use ATP)
  • always goes down concentration gradient
  • facilitates the transport of glucose across the cell membrane
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15
Q

How are carrier proteins (protein-mediated transport) DIFFERENT than channel proteins?

A
  • never open to ICF and ECF at the same time
  • does not actually “carry” because they stay in the membrane —> just changes shape
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16
Q

What is primary (direct) active transport?

A
  • a type of protein mediated transport from carrier proteins
  • uses ATP directly
  • ATP hydrolysis changes shape of the protein
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17
Q

What is secondary (indirect) active transport?

A
  • a type of protein mediated transport from carrier proteins
  • uses potential energy stored in concentration gradients of one molecule to push another molecule against its gradient
18
Q

What is an example of using a carrier protein? Is it active or passive?

A
  • Na K ATPase (sodium potassium pump)
  • moves Na into the cell, and K out of the cell
  • uses energy from ATP (hydrolyzes it)
19
Q

Slide 38 has sodium potassium pump

A
20
Q

What is an example of secondary active transport?

A
  • SGLT (sodium-glucose cotransport)
  • sodium and glucose transported into the ICF together
  • the Na binds to create a high affinity for glucose
  • No ATP used, just concentration gradient driving it
21
Q

What type of membrane protein exhibits specificity, competition, and saturation? What do they mean?

A
  • carrier-mediated transport
    1. Specificity: moving only one molecule or group of related molecules
    2. Competition: transporter ay move related substrates, but those substrates compete with one another for binding sites (competitive inhibitor)
    3. Saturation: the rate of substrate transport depends on the substrate concentration and the number of carrier molecules
22
Q

What is phagocytosis?

A

the process by which a cell engulfs a particle into a vesicle by using the cytoskeleton to push the membrane around the particle
- actin mediated process
- the membrane surface pushes out
- is triggered by the presence of a substance to be ingested

23
Q

What is endocytosis?

A
  • the membrane surface indents
  • forms small vesicles
  • constitutive: an essential function always taking place
  • active: requires energy from ATP
  • can be non selective (allowing extracellular fluid to enter the cell) or can be selective
  • can be receptor-mediated endocytosis
24
Q

What is exocytosis?

A
  • intracellular vesicles move to the cell membrane and fuse with it
  • they then release their contents to the extracellular fluid
  • cells use exocytosis to export large lipophobic molecules, get rid of wastes left in the lysosomes from intracellular digestion
25
Q

What is a phagosome?

A

the vesicle formed around ingested material during phagocytosis
- site of digestion

26
Q

What is receptor-mediated endocytosis?

A
  • takes place in regions of the cell known as “coated pits” (indentations where cytoplasmic side of the membrane has high concentrations of protein)
  • Most common protein found is Clathrin
27
Q

What is transcellular transport?

A
  • transport through the epithelial cells themselves
  • crosses 2 membranes
  • uses combo of active and passive transport
28
Q

What is paracellular transport?

A
  • transport thorugh the junctions between adjacent cells
  • very little in in “tight” epithelia (cell-cell junctions are like barriers)
29
Q

What is transcytosis?

A
  • a combination of endocytosis, vesicular transport across the cell, and exocytosis
  • used to move macromolecules across an epithelium
  • makes it possible for large proteins to move across an epithelium and remain intact
30
Q

What is absorption?

A

transfer of substance from the lumen of the kidney or GI tract to the extracellular space

31
Q

What is secretion?

A
  • when materials move from the ECF to the lumen
  • EX: salivary glands secret saliva
  • can also just mean the release of a substance from a cell
32
Q

What is the net charge of the ICF?

A

negative (compartments are in disequilibrium)

33
Q

What is the net charge between the ECF?

A

positive (compartments are in disequilibrium)

34
Q

What is the law of conservation of electrical charge?

A

the net amount of electrical charge produced in any process is zero
- for every positive charge ion there is an electron on another ion
- overall body is electrically neutral

35
Q

Which ion is the main regulator of membrane potential?

A

potassium (K+ leak channels) (most cells about 40x more permeable to K+ than Na+

36
Q

What does the nernst equation tell us?

A
  • used for a cell that is freely permeable to only one ion at a time
  • equation used to calculate equilibrium potential for any concentration gradient
  • is not used to calculate the actual membrane potential of the cells
37
Q

What is depolarization, repolarization, and hyperpolarization?

A
  1. depolarization: increase in RMP charge (more positive
  2. repolarization: decrease in RMP charge (more negative)
  3. hyperpolarization: happens after repolarization when the membrane becomes more negative
38
Q

What is the NA K ATPase used for in membrane potential?

A

helps maintain the resting membrane potential by removing Na+ that leaks into the cell and returning K+ that has leaked out

39
Q

Study the integrated membrane processes: insulin secretion (last couple of slides)

A
40
Q
A

BIOL 385 (9 decks)

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