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Bio Chem > Membrane Transport & Cell Signalling - 2a > Flashcards

Membrane Transport & Cell Signalling - 2a Flashcards

1
Q

What are the two main types of transport across the cell membrane?

A

Passive transport and active transport

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2
Q

What molecule is used as the source of energy for cellular processes?

A

ATP (adenosine triphosphate)

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3
Q

What type of transport is it when….. Molecules move LOW to HIGH concentration need ATP.

A

Active Transport

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4
Q

What type of transport is it when….. Molecules move HIGH to LOW concentration, no need of energy.

A

Passive Transport

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5
Q

What are the 3 types of Passive transport?

A

Simple diffusion, Facilitated diffusion, Osmosis

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6
Q

What is diffusion?

A

A passive process which means no energy is required to transport the substances.

It is possible because of the kinetic energy and the drive to move substances from an area of high concentration to one of low concentration (the electrochemical gradient).

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7
Q

What effects the speed of diffusion?

A

Steepness of concentration gradient, temperature of the solution, mass of the diffusing substance, surface area of the membrane, diffusion distance.

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8
Q

What is simple diffusion?

A

A passive process where particles can move freely across the plasma membrane

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9
Q

What types of particles can cross the plasma membrane via simple diffusion?

A

Particles that are small enough, hydrophobic (non-polar), or uncharged

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10
Q

Examples of very small hydrophobic substances that can cross the plasma membrane freely.

A
  • Oxygen
  • Carbon dioxide
  • Nitrogen
  • Small fatty acids
  • Steroid hormones
  • Fat-soluble vitamins
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11
Q

Fill in the blank: Simple diffusion is a _______ process.

A

passive

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12
Q

True or False: Only hydrophobic substances can cross the plasma membrane by simple diffusion.

A

False

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13
Q

Photo of simple diffusion across a membrane

A
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14
Q
A
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15
Q

What is facilitated diffusion?

A

Facilitated diffusion is the process by which substances cross the phospholipid bilayer with the help of integral membrane proteins.

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16
Q

Why do some substances require facilitated diffusion?

A

Substances that are too polar or highly charged need help to cross the phospholipid bilayer.

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17
Q

What role do integral membrane proteins play in facilitated diffusion?

A

Integral membrane proteins assist substances in crossing the membrane by providing specific pathways.

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18
Q

How is facilitated diffusion different from simple diffusion?

A

In simple diffusion, substances can cross anywhere on the membrane, whereas in facilitated diffusion, they can only cross where helper proteins are present.

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19
Q

Is facilitated diffusion a fast or slow process?

A

Facilitated diffusion is still super-fast; more than a million potassium ions can cross through a potassium channel in one second.

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20
Q

Fill in the blank: When diffusion uses integral proteins for assistance, it is called _______.

A

[facilitated diffusion]

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21
Q

True or False: Facilitated diffusion is faster than simple diffusion.

A

False

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22
Q

What happens to substances that are too polar or highly charged in terms of membrane crossing?

A

They need help to cross the phospholipid bilayer.

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23
Q

Here is a photo of facilitated diffusion:

A
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24
Q

What are the two types of integral membrane proteins involved in facilitated diffusion?

A

Protein channels and carriers

Protein channels are also known as pores, while carriers are referred to as transporters.

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25
What do channel proteins create?
Channel proteins create a passage (pore) through which substances can move across the membrane.
26
How do substances move through channel proteins?
Substances will move down their concentration gradient to the other side.
27
What type of channels are most channel proteins?
Most channels are ion channels, allowing specific small inorganic ions of a particular charge and type through.
28
What is an example of a potassium ion channel?
Potassium ion channels are selective for K+ (potassium ions). ## Footnote Example: Potassium ion channels are selective for K+ (potassium ions) while chloride ion channels only allow Cl- (chloride ions) to travel through.
29
What do chloride ion channels allow?
Chloride ion channels only allow Cl- (chloride ions) to travel through. ## Footnote Example: Potassium ion channels are selective for K+ (potassium ions) while chloride ion channels only allow Cl- (chloride ions) to travel through.
30
What are non-gated channels?
Non-gated channels are channels that are always open.
31
What are gated channels?
Gated channels have a 'gate' on one side that can be opened or closed. ## Footnote Some channels switch regularly between open and closed state. Others must receive a signal (usually a chemical or electrical signal) to trigger them to open.
32
What is the function of gates in gated channels? ## Footnote Simple Diffusion
Gates allow the cell some control over when substances can travel through the channel.
33
What are carrier proteins?
Carrier proteins (or transporters) function similarly to gated channels. They trigger a shape change when a molecule binds, moving it across the membrane.
34
How do carrier proteins operate?
When a molecule binds to the carrier, a shape change is triggered, moving the bound molecule across the membrane and releasing it on the other side.
35
Are carrier proteins specific to certain molecules?
Yes, carriers are usually molecule-specific and transport just one or two types of substances.
36
Can you provide an example of a carrier protein?
A glucose carrier has a specific glucose binding-site. Once bound, it triggers a shape change, moving glucose into the cell. ## Footnote Example: A glucose carrier has a specific glucose binding-site.
37
What is the direction of substance movement in passive transport?
Substances travel down (or 'with') their concentration gradient from high to low concentration.
38
Is cellular energy required for passive transport?
No cellular energy is required; kinetic (movement) energy is used (the gradient creates a pull).
39
What are the types of passive transport?
The types of this transport are: simple diffusion, facilitated diffusion, osmosis.
40
What are the passive transport mechanisms?
Osmosis, Simple Diffusion, Facilitated Diffusion
41
What are the active transport mechanisms?
Primary Active Transport, Secondary Active Transport, Vesicular Transport
42
What is osmosis?
Movement of water across a semi-permeable membrane from high to low water concentration or low to high solute concentration.
43
What is simple diffusion?
Movement of solutes from high to low concentration.
44
What is facilitated diffusion?
Uses integral proteins to transport solutes.
45
What is primary active transport?
Direct use of ATP to transport molecules. ## Footnote Example: Na+/K+ Pump (3 Na+ out, 2 K+ in)
46
What is secondary active transport?
Uses energy from Na+ or H+ gradient.
47
What are the types of secondary active transport?
Symporters (move two substances in the same direction) and Antiporters (move two substances in opposite directions).
48
What is vesicular transport?
Bulk transport including endocytosis and exocytosis.
49
What is the structure of the plasma membrane?
Bilipid layer made of amphipathic molecules: lipids & proteins.
50
What are the components of membrane lipids?
75% Phospholipid, 20% Cholesterol, 5% Glycolipid.
51
What are integral proteins?
Proteins that span the membrane.
52
What are peripheral proteins?
Proteins that are attached to the membrane surface.
53
What is a concentration gradient?
Difference in molecule concentration across the membrane. ## Footnote Example: Oxygen & Sodium ions (higher outside), Carbon Dioxide & Potassium ions (higher inside)
54
What is an electrical gradient?
Difference in electrical charges across the membrane.
55
What is an electrochemical gradient?
Combination of concentration and electrical gradients.
56
What is tonicity?
The effect of a solution on cell shape.
57
What is an isotonic solution?
No net water movement; cell maintains shape.
58
What is a hypotonic solution?
Water enters cell; cell swells and may burst (lysis).
59
What is a hypertonic solution?
Water leaves cell; cell shrinks (crenation).
60
What is somatic cell division?
Produces two identical diploid cells through mitosis and cytokinesis.
61
What is reproductive cell division?
Produces four genetically unique haploid cells through meiosis and cytokinesis.
62
What are the phases of somatic cell division?
Interphase → Prophase → Metaphase → Anaphase → Telophase (I P M A T).
63
What occurs during prophase I of meiosis?
Homologous chromosomes pair (tetrad formation) & crossing over occurs.
64
What occurs during metaphase I of meiosis?
Chromosomes align in homologous pairs.
65
What occurs during anaphase I of meiosis?
Homologous chromosomes separate.
66
What occurs during telophase I of meiosis?
Two new cells form (each with half the chromosomes).
67
What is the result of meiosis II?
Four non-identical haploid cells.

Bio Chem (15 decks)

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