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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
What are the molecules allowed by the carrier proteins to pass across the plasma membrane by facilitated diffusion
Glucose and amino acids
26
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.
extracellular glucose concentration
27
• provide corridors allowing water molecules to cross the membrane. • Allow for fast transport • water channel proteins make possible massive amounts of diffusion
Aquaporins
28
Aquaporins are protein pores used during ___
Osmosis
29
Aquaporins are protein pores used during ___
Osmosis
30
the diffusion of water across a differentially permeable membrane.
Osmosis
31
the pressure that develops in a system due to osmosis.
Osmotic pressure
32
3 concentration of water
Hypertonic Hypotonic Isotonic
33
More solute, less water
Hypertonic
34
Less solute, more water
Hypotonic
35
Equal solute, equal water
Isotonic
36
Net movement of water
Hypotonic -> Hypertonic
37
Cell survival depends on balancing __ __ and __
Water uptake and loss
38
What happens to animal cell in hypotonic solution (freshwater)
Cell is lysed
39
In the hypotonic solution, the waters ___ the cell via osmosis
Enters
40
What happens to animal cell in isotonic solution
Normal
41
What happens to the animal cell in the hypertonic solution?
Shriveled
42
What happens to the plant cell in the hypotonic solution
Cell is turgid (No bursting of cell due to the presence of cell wall)
43
What happens to the plant cell in the isotonic solution
Cell becomes flaccid
44
What happens to the plant cell in the hypertonic solution
Cell is plasmolyzed (cell membrane pull away from cell wall)
45
animal cell immersed in mild salt solution
Isotonic
46
Example of isotonic
Blood cells in blood plasma ( ang blood plasma kay isotonic fluid)
47
in isotonic, there is no net movement of water, instead?
Flows across membrane equally, in both directions
48
The volume of cell in isotonic is ___
Stable
49
A cell in fresh water
Hypotonic
50
Hypotonic example, problem, and solution
Example: Paramecium Problem: gains water, swells & can burst – water continually enters Paramecium cell Solution: contractile vacuole – pumps water out of cell – ATP
51
A cell in salt water
Hypertonic
52
Hypertonic example, problem, solution
• example: shellfish • problem: lose water & die • solution: take up water or pump out salt
53
Why is osmosis important to cells and humans?
• Cells remove water produced by cell respiration. • Large intestine cells transport water to bloodstream • Kidney cells form urine
54
diffuse through membrane channels.
Non-lipid soluble substances
55
Diffuse through membrane protein channels
Non-lipid soluble substances
56
Diffuse through membrane channels
Non-lipid soluble substances
57
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**.
electrochemical gradient
58
The membrane potential (voltage)
regulates the opening/closing of the channel.
59
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.
Membrane potential
60
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.
Membrane potential
61
Example of a specific stimulus:
i) Voltage; - VOLTAGE - GATED CHANNEL ii) Ligand; - LIGAND -GATED CHANNELS iii) Specific stress; - STRESS – ACTIVATED CHANNELS
62
permit the free passage of ions and small polar molecules through the outer membranes of bacteria.
Porins
63
mediate the passage of ions across plasma membranes.
Ion channels
64
channels open in response to the binding of neurotransmitters or other signaling molecules.
Ligand-gated
65
channels open in response to the binding of neurotransmitters or other signaling molecules.
Ligand-gated
66
channels open in response to changes in electric potential across the plasma membrane.
Voltage-gated
67
open or close depending on the presence or absence of a physical or chemical stimulus
Grated channels
68
Example of gated channels
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
Voltage-gated channels
K+ voltage-gated channels Na+ voltage-gated channels
70
exist as either open or close depending on the membrane voltage. It has only an activation gate.
K+ voltage-gated channels
71
opens when the membrane potential depolarizes (i.e. becomes more positive). - It has activation and inactivation gates.
Na+ voltage-gated channels

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