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(4) Transport Across The Plasma Membrane 2024 For Moodle > pack > Flashcards

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1
Q

What is the lipid bilayer?

A

The lipid bilayer is a permeability barrier.

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2
Q

What is the function of the plasma (cell) membrane?

A

The plasma (cell) membrane acts as a barrier but allows nutrients to enter and wastes to exit.

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3
Q

What determines what moves in and out of a cell?

A

Permeability determines what moves in and out of a cell.

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4
Q

What does selectively permeable mean for the plasma membrane?

A

A selectively permeable plasma membrane allows some materials to move freely while restricting others.

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5
Q

What are the factors that selective permeability is based on?

A

Selective permeability restricts materials based on size electrical charge molecular shape and lipid solubility.

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6
Q

What materials diffuse through the plasma membrane by simple diffusion?

A

Materials that diffuse through the plasma membrane by simple diffusion include lipid-soluble compounds (such as alcohols fatty acids and steroids) and dissolved gases (like oxygen and carbon dioxide).

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7
Q

What is channel-mediated diffusion?

A

Channel-mediated diffusion is the diffusion of water-soluble compounds and ions through the plasma membrane.

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8
Q

What factors affect channel-mediated diffusion?

A

Factors affecting channel-mediated diffusion include size charge and interaction with the channel (leak channels).

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9
Q

What is passive transport through a plasma membrane?

A

Passive transport through a plasma membrane does not require energy.

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10
Q

What is active transport through a plasma membrane?

A

Active transport through a plasma membrane requires energy and ATP.

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11
Q

What are the types of transport that can be passive?

A

Diffusion and carrier-mediated transport can be passive.

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12
Q

What are the types of transport that can be active?

A

Carrier-mediated transport and vesicular transport can be active.

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13
Q

What is diffusion?

A

Diffusion is a passive transport process where molecules move from an area of higher concentration to an area of lower concentration.

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14
Q

What is carrier-mediated transport?

A

Carrier-mediated transport can be either passive or active depending on whether energy is required.

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15
Q

What is vesicular transport?

A

Vesicular transport is an active transport process that requires energy.

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16
Q

How does molecule size affect diffusion?

A

Smaller molecules diffuse faster.

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17
Q

How does temperature affect diffusion?

A

Higher temperatures increase the motion of particles making diffusion faster.

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18
Q

What is a concentration gradient?

A

A concentration gradient is the difference between high and low concentrations.

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19
Q

How do electrical forces influence diffusion?

A

Electrical forces influence diffusion by attracting opposite charges and repelling like charges.

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20
Q

What are the two types of diffusion across plasma membranes?

A

Diffusion across plasma membranes can be simple or channel mediated.

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21
Q

What materials diffuse through the plasma membrane by simple diffusion?

A

Materials that diffuse through the plasma membrane by simple diffusion include lipid-soluble compounds such as alcohols fatty acids and steroids and dissolved gases such as oxygen and carbon dioxide.

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22
Q

What are the factors influencing channel-mediated diffusion?

A

Factors influencing channel-mediated diffusion include size charge and interaction with the channel such as leak channels.

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23
Q

What are water channels?

A

Water channels are specialized channels that allow water molecules to pass through the plasma membrane.

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24
Q

What are ion channels?

A

Ion channels are specific channels that allow ions to diffuse across the plasma membrane.

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25
Q

What are open channels?

A

Open channels are channels that remain open all the time allowing continuous diffusion of specific molecules.

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26
Q

What are gated channels?

A

Gated channels are channels that open or close in response to a stimulus.

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27
Q

What are chemically gated channels?

A

Chemically gated channels are channels that open or close in response to specific chemicals binding to them.

28
Q

What are voltage-gated channels?

A

Voltage-gated channels are channels that open or close in response to changes in membrane potential.

29
Q

What are mechanically gated channels?

A

Mechanically gated channels are channels that open or close in response to physical deformation of the membrane such as pressure or stretch.

30
Q

What are the characteristics of carrier-mediated transport?

A

The characteristics of carrier-mediated transport include specificity saturation limits and regulation.

31
Q

What does specificity mean in carrier-mediated transport?

A

Specificity means that one transport protein transports one set of substrates.

32
Q

What are saturation limits in carrier-mediated transport?

A

Saturation limits refer to the fact that the rate of transport depends on the number of transport proteins available not the amount of substrate.

33
Q

What does regulation mean in carrier-mediated transport?

A

Regulation in carrier-mediated transport involves cofactors such as hormones that can influence the activity of transport proteins.

34
Q

What is cotransport in carrier-mediated transport?

A

Cotransport is when two substances move in the same direction at the same time through a transport protein.

35
Q

What is counter-transport in carrier-mediated transport?

A

Counter-transport is when one substance moves into the cell while another moves out through a transport protein.

36
Q

How do carrier proteins transport large molecules like glucose and amino acids?

A

Carrier proteins transport large molecules by binding them to a receptor site changing shape and allowing the molecules to pass through.

37
Q

What happens when a molecule binds to a receptor site on a carrier protein?

A

When a molecule binds to a receptor site on a carrier protein the protein changes shape allowing the molecule to pass through.

38
Q

What is the specificity of receptor sites on carrier proteins?

A

Receptor sites on carrier proteins are specific to certain molecules ensuring that only the correct molecules are transported.

39
Q

What do active transport proteins do?

A

Active transport proteins move substrates against the concentration gradient and require energy such as ATP.

40
Q

What are ion pumps?

A

Ion pumps are active transport proteins that move ions such as Na+ K+ Ca2+ and Mg2+ against their concentration gradients.

41
Q

What is an exchange pump?

A

An exchange pump is a type of active transport protein that counter-transports two ions in opposite directions at the same time.

42
Q

What is primary active transport?

A

Primary active transport is a process where transport proteins use energy directly from ATP to move substances against their concentration gradient.

43
Q

What does the sodium-potassium exchange pump do?

A

The sodium-potassium exchange pump is a carrier-mediated active transport process that moves sodium ions Na+ out of the cell and potassium ions K+ into the cell.

44
Q

How many ions does the sodium-potassium exchange pump move per ATP?

A

The sodium-potassium exchange pump moves 3 sodium ions Na+ out of the cell and 2 potassium ions K+ into the cell per ATP.

45
Q

How does Na+ concentration gradient drive glucose transport in secondary active transport?

A

In secondary active transport the Na+ concentration gradient provides the energy to transport glucose against its concentration gradient into the cell.

46
Q

How is ATP involved in secondary active transport?

A

In secondary active transport ATP energy is used to pump Na+ back out of the cell to maintain the Na+ concentration gradient.

47
Q

How does osmosis relate to solute and water concentration?

A

In osmosis water molecules diffuse toward the solution with more solutes resulting in a lower concentration of free water molecules on that side.

48
Q

What must a membrane be for osmosis to occur?

A

For osmosis to occur the membrane must be freely permeable to water and selectively permeable to solutes.

49
Q

What happens to water molecules during osmosis?

A

During osmosis water molecules diffuse across the membrane toward the solution with a higher concentration of solutes.

50
Q

What happens to the volume on the side with more solutes during osmosis?

A

The volume increases on the side with more solutes during osmosis.

51
Q

What is endocytosis?

A

Endocytosis is a type of active transport using ATP where materials are brought into the cell within vesicles.

52
Q

What are the three types of endocytosis?

A

The three types of endocytosis are receptor-mediated endocytosis pinocytosis and phagocytosis.

53
Q

What happens during receptor-mediated endocytosis?

A

During receptor-mediated endocytosis receptors (glycoproteins) on the cell membrane bind to target molecules (ligands) and a coated vesicle (endosome) carries these ligands and receptors into the cell.

54
Q

What is pinocytosis?

A

Pinocytosis is a form of endocytosis where the cell engulfs extracellular fluid containing dissolved substances into small vesicles.

55
Q

What is phagocytosis?

A

Phagocytosis is a form of endocytosis where the cell engulfs large particles or debris into vesicles called phagosomes.

56
Q

What is endocytosis in vesicular transport?

A

Endocytosis is a type of vesicular transport where materials are brought into the cell from the outside.

57
Q

What is pinocytosis?

A

Pinocytosis is a form of endocytosis where endosomes “drink” extracellular fluid.

58
Q

What is phagocytosis?

A

Phagocytosis is a form of endocytosis where pseudopodia or “false feet” extend to engulf large objects into vesicles called phagosomes.

59
Q

What does pseudopodia mean?

A

Pseudopodia means “false feet” and are extensions of the cell membrane used in phagocytosis to engulf large objects.

60
Q

What is the basal membrane in epithelial transport?

A

The basal membrane is the surface of epithelial cells that faces the underlying connective tissue and is opposite the apical membrane.

61
Q

What is paracellular transport?

A

Paracellular transport is the movement of substances through the junctions between adjacent cells.

62
Q

What is transcellular transport?

A

Transcellular transport is the movement of substances directly through the cells themselves.

63
Q

What is transcytosis with vesicular transport?

A

Transcytosis with vesicular transport involves the movement of substances across a cell by vesicles that encapsulate the material for transport.

64
Q

What is the difference between absorption and secretion in epithelial transport?

A

Absorption is the process of moving substances from the lumen to the extracellular fluid (ECF) while secretion is the movement of substances from the ECF to the lumen.

65
Q

How does transcellular transport of glucose occur?

A

Transcellular transport of glucose occurs through the use of membrane proteins that facilitate its movement across the cell membrane.

(4) Transport Across The Plasma Membrane 2024 For Moodle (4 decks)

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