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BI 338 Cells > Membrane Transport (Lecture 9) > Flashcards

Membrane Transport (Lecture 9) Flashcards

1
Q

What would pure lipid bilayers only be permeable to?

A

gases, small uncharged polar molecules

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2
Q

True or False: Life wouldn’t be possible with a pure lipid bilayer.

A

True

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3
Q

A _____ K value means hydrophobic and easier to cross the lipid bilayer.

A

High

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4
Q

What are the 3 types of membrane transport protein ?

A

Channels
Transporters (uniporter, antiporter, symporter)
ATP-powered pumps

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5
Q

Channels move molecules ______ the concentration gradient.

A

Down

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6
Q

Uniporters move 1 molecule ______ the concentration gradient.

A

Down

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7
Q

______ and ______ transport 2 molecules: one down its concentration gradient, and one up its concentration gradient.

A

Symporter and antiporters

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8
Q

What is secondary active transport?

A

uses energy of an existing electrochemical gradient

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9
Q

True or False: ATP-powered pumps is the slowest form of transport.

A

True

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10
Q

True or False: ATP-powered pumps use energy of ATP hydrolysis to transport up a chemical concentration gradient, electric potential, or both.

A

True

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11
Q

What are the three types of free transport?

A

Simple diffusion, channel, uniporters

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12
Q

What are the three types of costly transporters.

A

Symporters, antiporters, ATP-powered pumps

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13
Q

True or False: Conformational changes are essential for transport proteins.

A

True

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14
Q

How do multiple membrane transporters work together?

A

Na+/K+ pump (ATPase) pumps Na+ out of the cell and K+ inward
— Sets up gradients of Na+ and K+ across the membrane —
Primary active transport
—
Na+/lysine symporter brings lysine into cell along with two Na+
Na+ gradient used to power import of lysine —
Secondary active transport
—
K+ channel releases K+ down its gradient
— Maintains electric potential across membrane (+ out, - in) —
Facilitated transport

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15
Q

True or False: Uniport is faster and more specific than diffusion.

A

True

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16
Q

______ is the maximum transport rate (when all of the available uniporters have substrate and are working at the maximal rate)

A

Vmax

17
Q

______ is a measure of affinity for the substrate (“how good it is at binding”), and is the concentration of substrate at half Vmax

A

Km

18
Q

True or False: The partition coefficient is irrelevant when using a uniport.

A

True

19
Q

True or False: The lower the value of Km, the more tightly the substrate binds to the transporter.

A

True

20
Q

True or False: The higher the Km the faster the reaction.

A

False, the lower the Km

21
Q

What is the first step in metabolism of glucose?

A

Phosphorylation

22
Q

True or False: Conformational changes are reversible.

A

True

23
Q

True or False: Aquaporins Increase Water Permeability of Cellular Membranes.

A

True

24
Q

True or False: The aquaporin has conformational changes.

A

False, they do not

BI 338 Cells (21 decks)

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