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z > 2b - Cell Membrane Transport > Flashcards

2b - Cell Membrane Transport Flashcards

1
Q

What goes in and out of the cell?

A

In - food
Out - waste

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2
Q

The property of the cell membrane that allows some materials to pass and prevents others from passing.

A

Differentially (Selectively) Permeable

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3
Q

Factors that determine how a substance may be transported across a plasma membrane:

A

– Size
– Polar or Nonpolar
– charge

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4
Q

Movement of molecules across membrane from high to low concentration without the need for energy input

A

Passive diffusion

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5
Q
  • 2nd Law of Thermodynamics
  • governs biological systems
    – universe tends towards disorder
    (entropy)
A

PASSIVE DIFFUSION

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6
Q

Net movement of passive diffusion

A

High concentration to low concentration

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7
Q

What kind of molecules are able to
diffuse across a phospholipid bilayer
at significant rates by using passive
diffusion.

A

Small and hydrophobic molecules

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8
Q

Why is diffusion important to cells
and humans?

A

• Cell respiration
• Alveoli of lungs
• Capillaries
• Red Blood Cell

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9
Q

is a form of energy generated by the movement of protons (H⁺ ions) across a membrane.

A

Proton motive force

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10
Q

How PMF is generated

A

In mitochondria (for cellular respiration) or chloroplasts (for photosynthesis), electrons are transferred through a series of proteins embedded in the inner mitochondrial membrane or thylakoid membrane. As electrons move through the ETC, energy released from these redox reactions is used to pump protons from the mitochondrial matrix into the intermembrane space or from the stroma into the thylakoid lumen. This creates a proton gradient.

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11
Q

Example of molecules that pass through protein channels

A

• Ions
(Na+, K+, Cl-)
• Sugars (Glucose)
• Amino Acids
• Small water soluble molecules
• Water (faster rate)

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12
Q
  • Diffusion through protein channels which do not interact with hydrophobic interior
    – For biological mol unable to dissolve in hydrophobic interior
    – no energy needed
A

Facilitated diffusion

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13
Q

facilitated=

A

With help

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14
Q

Open channel=

A

Fast transport

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15
Q

Aids the passage of materials

A

Concentration gradient
Transport proteins

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16
Q

bind specific molecules, undergo conformational change to release molecule

A

Carrier protein

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17
Q

Example of Carrier protein

A

Glucose transporters

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18
Q
  • form open pores for free diffusion
  • found in gap junctions
A

Channel protein

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19
Q

proteins that facilitate the movement of glucose across cell membranes.

A

Glucose transporters

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20
Q

Molecules will randomly move through the pores
in ___
Proteins.

A

Channel protein

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21
Q

Some ___ proteins do not extend
through the membrane. Instead, they bond and drag molecules
through the lipid bilayer and release
them on the opposite side

A

Carrier

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22
Q

Other __ proteins change shape to move materials across the cell
membrane

A

Carrier

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23
Q

is rate limited, by the number of
proteins channels/carriers present in the membrane.

A

Facilitated diffusion

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24
Q

What are the molecules allowed by the channel proteins to pass across the plasma membrane by facilitated diffusion

A

ions, small solutes, and water

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25
Q

What are the molecules allowed by the carrier proteins to pass across the plasma membrane by facilitated diffusion

A

Glucose and amino acids

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26
Q

Most cells, including erythrocytes, are exposed to ____ ___ concentrations that are higher than those inside the cell, so facilitated diffusion results in the net inward transport of glucose.

A

extracellular glucose concentration

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27
Q

• provide corridors allowing water
molecules to cross the membrane.
• Allow for fast transport
• water channel proteins make possible massive amounts of diffusion

A

Aquaporins

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28
Q

Aquaporins are protein pores used during ___

A

Osmosis

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29
Q

Aquaporins are protein pores used during ___

A

Osmosis

30
Q

the diffusion of water across a differentially permeable membrane.

A

Osmosis

31
Q

the pressure that develops in a system due to osmosis.

A

Osmotic pressure

32
Q

3 concentration of water

A

Hypertonic
Hypotonic
Isotonic

33
Q

More solute, less water

A

Hypertonic

34
Q

Less solute, more water

A

Hypotonic

35
Q

Equal solute, equal water

A

Isotonic

36
Q

Net movement of water

A

Hypotonic -> Hypertonic

37
Q

Cell survival depends on balancing __ __ and __

A

Water uptake and loss

38
Q

What happens to animal cell in hypotonic solution (freshwater)

A

Cell is lysed

39
Q

In the hypotonic solution, the waters ___ the cell via osmosis

A

Enters

40
Q

What happens to animal cell in isotonic solution

A

Normal

41
Q

What happens to the animal cell in the hypertonic solution?

A

Shriveled

42
Q

What happens to the plant cell in the hypotonic solution

A

Cell is turgid
(No bursting of cell due to the presence of cell wall)

43
Q

What happens to the plant cell in the isotonic solution

A

Cell becomes flaccid

44
Q

What happens to the plant cell in the hypertonic solution

A

Cell is plasmolyzed (cell membrane pull away from cell wall)

45
Q

animal cell immersed in mild salt solution

A

Isotonic

46
Q

Example of isotonic

A

Blood cells in blood plasma ( ang blood plasma kay isotonic fluid)

47
Q

in isotonic, there is no net movement of water, instead?

A

Flows across membrane equally, in both directions

48
Q

The volume of cell in isotonic is ___

A

Stable

49
Q

A cell in fresh water

A

Hypotonic

50
Q

Hypotonic example, problem, and solution

A

Example: Paramecium
Problem: gains water,
swells & can burst
– water continually enters
Paramecium cell
Solution: contractile vacuole
– pumps water out of cell
– ATP

51
Q

A cell in salt water

A

Hypertonic

52
Q

Hypertonic example, problem, solution

A

• example: shellfish
• problem: lose water & die
• solution: take up water or
pump out salt

53
Q

Why is osmosis important to cells and humans?

A

• Cells remove water produced by cell
respiration.
• Large intestine cells transport water to bloodstream
• Kidney cells form urine

54
Q

diffuse through membrane
channels.

A

Non-lipid soluble substances

55
Q

Diffuse through membrane protein channels

A

Non-lipid soluble substances

56
Q

Diffuse through membrane channels

A

Non-lipid soluble substances

57
Q

They non-lipid soluble substances passively diffuse down their ____ ____ through channels that cross the lipid bilayer; some channels are open all
the time whereas others are
gated.

A

electrochemical
gradient

58
Q

The membrane potential
(voltage)

A

regulates the opening/closing of the
channel.

59
Q

refers to the electrical difference (voltage) across a cell’s plasma membrane. It arises due to the unequal distribution of ions (charged particles) inside and outside the cell.

A

Membrane potential

60
Q

refers to the electrical difference (voltage) across a cell’s plasma membrane. It arises due to the unequal distribution of ions (charged particles) inside and outside the cell.

A

Membrane potential

61
Q

Example of a specific stimulus:

A

i) Voltage; - VOLTAGE - GATED
CHANNEL
ii) Ligand; - LIGAND -GATED
CHANNELS
iii) Specific stress; - STRESS –
ACTIVATED CHANNELS

62
Q

permit the free passage
of ions and small polar
molecules through the outer
membranes of bacteria.

A

Porins

63
Q

mediate the
passage of ions across plasma
membranes.

A

Ion channels

64
Q

channels open in
response to the binding of
neurotransmitters or other
signaling molecules.

A

Ligand-gated

65
Q

channels open in
response to the binding of
neurotransmitters or other
signaling molecules.

A

Ligand-gated

66
Q

channels open in response to changes in electric potential across the plasma membrane.

A

Voltage-gated

67
Q

open or close depending
on the presence or absence
of a physical or chemical
stimulus

A

Grated channels

68
Q

Example of gated channels

A

neurotransmitters bind to specific gated channels on the receiving neuron, these channels open.
This allows sodium ion into a nerve cell.
When the neurotransmitters are not
present, the channels are closed.

69
Q

Voltage-gated channels

A

K+ voltage-gated channels
Na+ voltage-gated channels

70
Q

exist as either open or close depending on the membrane voltage. It has only an activation gate.

A

K+ voltage-gated channels

71
Q

opens when the membrane
potential depolarizes (i.e.
becomes more positive).
- It has activation and
inactivation gates.

A

Na+ voltage-gated channels

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