Membrane Transport Flashcards

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1
Q

Polar molecules

A

Such as sugars do not cross the membrane easily

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2
Q

Passive transport

A

Is a diffusion of a substance across a membrane with no energy investment

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3
Q

Diffusion

A

Tendency for molecules to spread out evenly into the available space

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4
Q

Dynamic equilibrium

A

As many molecules cross the membrane in one direction as in the other

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5
Q

At higher temperature the diffusion rate is

A

Greater

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6
Q

At a given temperature smaller molecules diffuse faster ?

A

True

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7
Q

Osmosis

A

Is diffusion of water across a selectively permeable membrane

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8
Q

How does water diffuses across a membrane?

A

from the region of lower solute concentration to region of higher solute concentration until the solute concentration is equal on both sides

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9
Q

Hydrophobic (NONPOLAR) molecules

A

Can dissolve in lipid bilayer and pass through the membrane rapidly

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10
Q

Tonicity

A

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

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11
Q

Isotonic solution

A

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

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12
Q

Hypertonic solution

A

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

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13
Q

Hypotonic solution

A

Solute concentration is less than That inside the cell, cell gains water

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14
Q

Plasmolysis

A

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

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15
Q

Active transport requires energy in ur form of

A

ATP

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16
Q

How is active transport performed ?

A

By specific proteins embedded in the membranes

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17
Q

Types of transport

A

Uniform
Symport
Antiport

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18
Q

Uniport

A

Single substance is moved in single direction

19
Q

2 types of Co transport ?

A

Symport and antiport

Where 2 different substances are moved together

20
Q

Symport

A

Two different substances are moved in same direction

21
Q

Antiport

A

One substance moved in one direction whole another moved in opposite direction

22
Q

Aquaporins

A

Membrane channels that allow water to cross the membrane

23
Q

Acetylcholine

A

Neurotransmitter, in the absence of it, the ion channel is closed when present the transporter gets triggered or hated by this small molecule ACh

24
Q

Na+/K+ pump

A

The sodium potassium pump is essential for active transport in all animal cells but not plants or most microbes

25
Q

Explain the sodium potassium pump

A

3 Na+ bond to the pump on the cytoplasmic side
ATP hydrolysis phosphorylates the pump
2 K+ ions bind to the pump of the extracellular side
Phosphate group is released causing a conformational change that releases the K+ ions into the cell
The pump is returned to its iriginla conformation and can repeat the cycle

26
Q

Phosphorylation

A

Causes a conformational change in the pump that releases the Na+ ions out the cell

27
Q

The net effect of Na+ K+ pump is ?

A

is to increase concentration of Na+ outside the cell and K+ inside the cell.
Since both are accumulated against concentration gradients, energy is required from ATP

28
Q

Membrane potential ?

A

Is the voltage difference across a membrane

29
Q

How is voltage created ?

A

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

30
Q

Electrochemical gradient?

A

Two combined forces that drive the diffusion of ions across a membrane

31
Q

A chemical force ?

A

The ions concentration gradient

32
Q

An electrical force ?

A

The effect of the membrane potential on the ions movement

33
Q

Electrogenic pump ?

A

Is a transport protein that generates voltage across a membrane

34
Q

Major electrogenic pump of animal cells?

A

Sodium-potassium pump

35
Q

Major electrogenic pump of plants fungi and bacteria is ?

A

Proton pump

36
Q

Secondary active transport

A

Movement of a substance is indirectly achieved by movement of second substance

37
Q

Exocytosis

A

Substances are directed out of a cell to be secreated by fusing a vesicle to the cell membrane

38
Q

Substances are shuttled into out of and within a cell through ?

A

Vesicles

39
Q

Endocytosis

A

Substances are engulfed into a cell by the formation of a vesicle around them

40
Q

Types of endocytosis ?

A

Phagocytosis
Pinocytosis
Receptor-mediated endocytosis

41
Q

Phagocytosis

A

Large particles are engulfed by pseudopodia formed by extensions of the cell membrane

42
Q

Pinocytosis

A

Liquids and small particles are captured in vesicles formed by unfolding of the cell membrane

43
Q

Receptor-mediated endocytosis

A

Vesicles are coated with receptors that recognize specific Ligands for endocytosis

44
Q

Macrophages

A

Pathogens are engulfed by the macrophage into a vesicle during endocytosis