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Biochemistry > Lecture 17 + 18, Transport Proteins (Ford) > Flashcards

Lecture 17 + 18, Transport Proteins (Ford) Flashcards

1
Q

List the 2 methods to cross a membrane.

A

Active or passive transport

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2
Q

Describe passive transport.

A

No energy needed, solute travels down concentration gradient

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3
Q

Describe active transport.

A

Coupled to ATP hydrolysis, solute travels against concentration gradient

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4
Q

What are the 3 general modes of transport across a membrane?

A

Antiport, synport, uniport

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5
Q

List the 3 general categories of transporters.

A

Pumps, carriers, channels

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6
Q

Describe pumps.

A

Perform primary active transport

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7
Q

Describe carriers.

A

Traverse membrane without needing extra energy

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8
Q

Describe channels.

A

Used in passive transport

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9
Q

T or F: P-type pumps phosphorylate themselves.

A

True.

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10
Q

T or F: V-type proton pumps make ATP.

A

False. V-type proton pumps use ATP, while F-type ATP synthase makes ATP.

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11
Q

What are the 4 domains of P-type ATPases?

A

Transmembrane domain, actuator domain, nucleotide binding domain, phosphorylation domain

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12
Q

T or F: The transmembrane domain of a P-type ATPase spans the lipid bilayer.

A

True.

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13
Q

Describe the actuator domain of a P-type ATPase.

A

Links cytosolic domains to the transmembrane domain

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14
Q

Which domain of the P-type ATPase binds ATP?

A

Nucleotide binding domain

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15
Q

Which domain of the P-type ATPase accepts the phosphate from ATP?

A

Phosphorylation domain

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16
Q

Outline the action of SERCA.

A
  1. E1 unphosphorylated, Ca++ ions bound
  2. ATP binds, Ca++ ions trapped
  3. ATP hydrolysis, self phosphorylation
  4. Eversion to E2, Ca++ ions released
  5. Release of Pi
  6. Eversion to E1
17
Q

T or F: The E1 state of SERCA is open to the outside.

A

False. The E1 state of SERCA is open to the inside.

18
Q

Outline the action of the Na++/K+ pump.

A
  1. E1, Na+ ions bound, ATP bound
  2. Na+ ions trapped
  3. ATP hydrolysis, self phosphorylation
  4. Eversion to E2, Na+ ions released
  5. Binding of K+
  6. K+ ions trapped, release of Pi, ATP rebinding
  7. Eversion to E1
  8. Release of K+
19
Q

Describe an application of primary active transport.

A

Digitalis and ouabain both lock the Na+/K+ pump in the E2 conformation.

20
Q

Outline the action of an ABC transporter.

A
  1. Empty transporter
  2. Small molecule binds and is trapped; ATP binding site affinity increases
  3. 2 ATPs bind causing eversion
  4. Small molecule is released
  5. ATP hydrolysis and release
21
Q

How is secondary active transport carried out?

A

After primary active transport creates a gradient, a passive channel or carrier allows ions/molecules to fall back down the gradient with a high value stowaway.

22
Q

Outline the secondary active transport action of lactose permease.

A
  1. Empty carrier, H+ binds and increases affinity for lactose
  2. Lactose binds
  3. Eversion
  4. Lactose released
  5. Deprotonation
  6. Eversion
23
Q

T or F: By definition, all secondary transporters are antiporters.

A

False. By definition, all secondary transporters are symporters.

24
Q

List the factors affecting diffusion rates.

A
  1. Magnitude of the concentration gradient
  2. Size of the molecule
  3. Surface area:volume ratio (shape)
  4. Temperature
  5. Density of solvent
  6. Solubility of solute
  7. Distance to destination
25
Q

How will a larger concentration gradient affect diffusion rate?

A

Faster

26
Q

How will a smaller molecule affect diffusion rate?

A

Faster

27
Q

How will a higher surface area:volume ratio affect diffusion rate?

A

Faster

28
Q

How will a lower temperature affect diffusion rate?

A

Slower

29
Q

How will a solvent with high density affect diffusion rate?

A

Slower

30
Q

How will a nonpolar solute affect diffusion rate?

A

Soluble

31
Q

How will a longer distance to the destination affect diffusion rate?

A

Slower

32
Q

What are 2 important pieces of an ion channel?

A
  1. Selectivity filter

2. Gate

33
Q

What does movement result from in a bacterial K+ channel?

A

Results form electrostatic repulsion

34
Q

What are the 3 ways to gate a channel?

A
  1. Voltage
  2. Ligand
  3. Stress
35
Q

Describe the 5 ion channels that work together to contact the muscles.

A
  1. Depolarization opens voltage-gated Ca++ channels
  2. Exocytosed acetylcholine opens ligand-gated Na+ channels
  3. Local depolarization opens adjacent voltage-gated Na+ channels
  4. As the depolarization spreads, voltage gated Ca++ channels open
  5. Coupled Ca++ release channels embedded in SR open
36
Q

What are the various proteins that facilitate diffusion?

A

Ion channels

37
Q

Describe gap junctions.

A

Channel, allow cytoplasm sharing, no specificity filter

38
Q

Describe aquaporins.

A

Channel, let water but not ions through

Biochemistry (10 decks)

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