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Anatomy 1 > 1.4: Cell Membranes and Diffusion Principles > Flashcards

1.4: Cell Membranes and Diffusion Principles Flashcards

1
Q

In 1972, the fluid-mosaic model of membrane structure was introduced, which proposes that……

A

……the membrane is a phospholipid bi-layer in which proteins are either partially or entirely embedded, like tiles in a mosaic picture.

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2
Q

What year was the the fluid-mosaic model of membrane structure introduced?

A

1972

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3
Q

The fluid-mosaic model of membrane structure proposes that the membrane is a ______ in which proteins are either partially or entirely embedded, like tiles in a mosaic picture.

A

phospholipid bi-layer

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4
Q

This mosaic pattern of the fluid-mosaic model of membrane structure is not static because the positions of the ___1___ and ___2___ are “___3___” and can move around within the membrane.

A
  1. proteins
  2. phospholipids
  3. fluid
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5
Q
A
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6
Q

A membrane has, primarily, two components. What are they?

A

lipids and proteins

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7
Q

Most of the lipids in the membrane are ___1___ and arrange themselves into a bi-layer with their ___2___ comprising the inner and outer faces of the membrane and their ___3___ facing each other to form the core of the membrane.

A
  1. amphipathic phospholipids
  2. polar (hydrophilic) heads
  3. non-polar (hydrophobic) tails
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8
Q

Most of the ___1___ in the membrane are amphipathic phospholipids and arrange themselves into a bi-layer with their polar (hydrophilic) heads comprising the ___2___ faces of the membrane and their non-polar (hydrophobic) tails facing ___3___ membrane.

A
  1. lipids
  2. inner & outer
  3. each other to form the core of the
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9
Q

Hydrophilic means what?

A

Water loving

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10
Q

_____ means water loving.

A

Hydrophilic

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11
Q

hydrophobic means what?

A

water hating.

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12
Q

______ means water hating.

A

hydrophobic

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13
Q

Polar substances are attracted to what?

A

Water

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14
Q

______substances are attracted to water.

A

Polar

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15
Q

Non-polar substances repel what?

A

Water

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16
Q

______ substances repel water.

A

Non-polar

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17
Q

The heads of amphipathic phospholipids face out because of their ___1___, while the tails face the inner portion because of how they ___2___.

A
  1. attraction to water
  2. repel water
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18
Q

While the heads of the amphipathic phospholipids of the membrane are arranged in an orderly fashion, the tails are ______.

A

in constant fluid motion

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19
Q

The movement of the tails allows the lipids to ___1___ and ___2___, but always with the head facing outward and the tail inward.

A
  1. rotate
  2. to move laterally within their layer
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20
Q

The fluidity of the lipids also allows for what?

A

Protein movement within the membrane structure

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21
Q

Some membranes contain ______ as a stabilizer against heat and cold.

A

cholesterol

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22
Q

Cholesterol acts as a what when contained in a membrane?

A

Stabilizer against heat and cold.

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23
Q

Cholesterol is a what?

A

A steroid lipid, that is largely hydrophobic with a single polar hydroxyl group.

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24
Q

The hydroxyl group in Cholesterol is attracted to the ___1___ of the phospholipids, while the rest of the cholesterol molecule lines up with the ___2___.

A
  1. polar heads
  2. phospholipid tails
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25
Q

The cholesterol molecules act as ___1___ between the tails to reduce solidification during ___2___.

A
  1. spacers
  2. low temperatures
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26
Q

Cholesterol also stabilizes the head during ___1___ by restricting ___2___ as energy is added to the system.

A
  1. elevated temperatures
  2. motion and preventing movement
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27
Q

Proteins are the other major constituent of membranes and include ______, which typically span across the lipid bi-layer.

A

integral proteins

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28
Q

______are located only on the inner or outer surfaces of the membrane.

A

Peripheral proteins

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29
Q

Peripheral proteins are located were?

A

On the inner or outer surfaces of the membrane.

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30
Q

______ are firmly bound within the membrane.

A

Integral proteins

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31
Q

Integral proteins are bound were?

A

Firmly bound within the membrane.

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32
Q

______ usually have one or more hydrophobic regions embedded in the core of the lipid bi-layer with hydrophilic regions that extend out of each face.

A

Integral proteins

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33
Q

Integral proteins usually have one or more ___1___ regions embedded in the core of the lipid bi-layer with ___2___ regions that extend out of each face.

A
  1. hydrophobic
  2. hydrophilic
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34
Q

True or False: Some integral proteins are large enough to weave back and forth through the membrane several times.

A

True

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35
Q

True or False: Peripheral proteins can not attach to exposed regions of integral proteins.

A

False. They can

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36
Q
A
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37
Q

Most membranes (both cell and organelle) are ______ with each face of the bi-layer differing in both lipid and protein content.

A

asymmetric

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38
Q

The unique arrangement of lipids and proteins in each face is responsible for the ___1___ of the membrane, allowing certain materials to pass in only one direction—___2___ move into the cell and ___3___ move out of the cell.

A
  1. selective permeability
  2. nutrients
  3. wastes
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39
Q

What are three methods by which particles cross a selectively permeable membrane?

A
  1. diffusion
  2. active transport
  3. special methods of endocytosis and exocytosis.
40
Q

What is Diffusion?

A

Is the first method for particles to be able to cross a cell membrane. Small molecules move from an area of higher concentration on one side of the membrane to an area of lower concentration on the other side. This flow of molecules continues until the molecules are equally distributed (their concentrations are equal) on either side of the membrane. Diffusion occurs naturally as small particles collide with one another, spreading out as they go. Diffusion is also called passive transport because the cell does not need to expend energy in the diffusion process. Think of aromas and perfumes permeating an entire room.

41
Q

What is it called when when small molecules move from an area of higher concentration on one side of the membrane to an area of lower concentration on the other side.

A

Diffusion

42
Q

______is the first method for particles to be able to cross a cell membrane. Small molecules move from an area of higher concentration on one side of the membrane to an area of lower concentration on the other side. This flow of molecules continues until the molecules are equally distributed (their concentrations are equal) on either side of the membrane. Diffusion occurs naturally as small particles collide with one another, spreading out as they go. Diffusion is also called passive transport because the cell does not need to expend energy in the diffusion process. Think of aromas and perfumes permeating an entire room.

A

Diffusion

43
Q

In Diffusion when do the flow of molecules stop?

A

This flow of molecules continues until the molecules are equally distributed (their concentrations are equal) on either side of the membrane.

44
Q

Diffusion occurs ______ as small particles collide with one another, spreading out as they go.

A

naturally

45
Q

Diffusion is also called ______.

A

passive transport

46
Q

Why is Diffusion sometimes referred to as Passive Transport?

A

Because the cell does not need to expend energy in the diffusion process.

47
Q

True or False: In all types of diffusion particles move naturally from an area of higher concentration to one of lower concentration.

A

True

48
Q

What is concentration gradient?

A

Is a difference in the concentration of a substance from one place to another.

49
Q

Diffusion is a form of passive transport because……

A

…… more energy is released than is required.

50
Q

True or False: Gases disperse unevenly through diffusion.

A

False. Gases disperse equally through diffusion.

51
Q

The diffusion of water is called ______.

A

Osmosis

52
Q

Osmosis is the diffusion of ______.

A

Water

53
Q

What are the three terms often used in biology to describe solute solution?

A
  1. isotonic
  2. hypertonic
  3. hypotonic
54
Q

______ refers to having an equal amount of solute on either side of a membrane.

A

Isotonic

55
Q

Isotonic refers to……

A

……having an equal amount of solute on either side of a membrane.

56
Q

Solute particles can be……..

A

……sugars, salts, and other substances within an aqueous solution.

57
Q

Each cell possesses a certain number of ______.

A

solute particles

58
Q

Describe what would happen if a blood cell were placed in an isotonic solution.

A

Some water molecules will randomly move from within the cell outward and some will move from outside the cell inward. However, there will be no net movement of water, and the cell will neither shrink nor swell.

59
Q

What does “Hyper” mean?

A

Above

60
Q

Describe what would happen if a blood cell were placed in a Hypertonic solution.

A

The cell would lose water and shrink in size. This is because the hypertonic solution contains more solute particles than the cell and, conversely, has a lower water concentration. The movement of water naturally flows from an area of greater concentration (inside the cell) to one of lesser.

61
Q

In a hypotonic solution, the solute particles outside of a cell are……

A

……of lesser concentration than inside the cell.

62
Q

In a ______, the solute particles outside of a cell are of lesser concentration than inside the cell.

A

hypotonic solution

63
Q

Describe what would happen if a blood cell were placed in a Hypotonic solution.

A

Water concentration is greater outside of the cell and naturally causes the water to move inward causing the cell to swell and even burst.

64
Q
A
65
Q

True or False: While small molecules (including gases, water, and glycerol) and lipid-soluble substances (such as hydrocarbons) can diffuse through a membrane relatively unaided, larger lipid-insoluble (polar) molecules, such as sugars and amino acids, cannot.

A

True

66
Q

______ is the diffusion of lipid-insoluble molecules across a membrane.

A

Facilitated diffusion

67
Q

Facilitated diffusion is……

A

…… the diffusion of lipid-insoluble molecules across a membrane

68
Q

To facilitate means ______.

A

to ease

69
Q

In Facilitated diffusion a ______ specific for a certain molecule temporarily binds to the molecule and then releases it to the other side.

A

integral carrier protein

70
Q

______ occurs when molecules or ions are pumped from an area of lower concentration to one of greater concentration (against the concentration gradient).

A

Active Transport

71
Q

Active transport occurs when…….

A

…… molecules or ions are pumped from an area of lower concentration to one of greater concentration (against the concentration gradient).

72
Q

Because the molecules do not naturally want to move against the concentration gradient, both ___1___ and ___2___ are required.

A
  1. carrier proteins
  2. additional energy
73
Q

One example of active transport is the ______, which maintains an electrical imbalance across the membrane.

A

sodium-potassium pump

74
Q

One example of active transport is the sodium-potassium pump, which……

A

…… maintains an electrical imbalance across the membrane.

75
Q
A
76
Q

True or False: Biomacromolecules, such as polysaccharides, proteins, and nucleic acids may be transported across cell membranes by carrier proteins and require no special transport methods.

A

False. Biomacromolecules, such as polysaccharides, proteins, and nucleic acids, because of their extremely large size, cannot be transported across cell membranes by carrier proteins and require special transport methods.

77
Q

______ occurs when a biomacromolecule is enclosed inside the membrane of a vesicle (usually formed by breaking off the Golgi complex), which then fuses with the cell membrane ejecting the biomacromolecule from the cell

A

Exocytosis

78
Q

Exocytosis occurs when……

A

……a biomacromolecule is enclosed inside the membrane of a vesicle (usually formed by breaking off the Golgi complex), which then fuses with the cell membrane ejecting the biomacromolecule from the cell

79
Q

exo- refers to ______

A

going out

80
Q

______ can occur between the cell membrane and Golgi complex because both are composed of a phospholipid bi-layer.

A

Fusion

81
Q

Fusion can occur between the cell membrane and Golgi complex because both are ______.

A

composed of a phospholipid bi-layer

82
Q

______ occurs when a biomacromolecule outside of the cell is enclosed in an invagination of the cell membrane, forming a vesicle inside the cell.

A

Endocytosis

83
Q

Endocytosis occurs when……

A

……a biomacromolecule outside of the cell is enclosed in an invagination of the cell membrane, forming a vesicle inside the cell.

84
Q

endo- refers to ______.

A

bringing in

85
Q

Endocytosis includes what three specialized transportation methods?

A
  1. phagocytosis
  2. pinocytosis
  3. receptor-mediated endocytosis
86
Q

______ is endocytosis of extremely large objects, such as other cells. Once the cell is enclosed in a vesicle, it fuses with lysosomes inside the cell and is digested. White blood cells use this to destroy harmful bacteria.

A

Phagocytosis

87
Q

Phagocytosis is endocytosis of……

A

…… extremely large objects, such as other cells. Once the cell is enclosed in a vesicle, it fuses with lysosomes inside the cell and is digested. White blood cells use phagocytosis to destroy harmful bacteria.

88
Q

______ is endocytosis of tiny droplets of fluids. This process is like phagocytosis except the cell membrane “pinches” inward without needing to extend pseudopods to ingest material.

A

Pinocytosis

89
Q

Pinocytosis is endocytosis of……

A

…… tiny droplets of fluids. This process is like phagocytosis except the cell membrane “pinches” inward without needing to extend pseudopods to ingest material.

90
Q

True or False: Another role of the proteins in cell membranes is information transfer from one cell to another.

A

True.

91
Q

______, Receptor proteins (integral) in a cell membrane bind with a signaling molecule sent from another cell. The signaling molecule (known in general as a ligand) is often in the form of a hormone. The receptor protein is responsible for transferring the signal across the membrane. When the ligand binds to the receptor protein, it changes the shape of the protein. Because the receptor protein is in close proximity to other proteins, their shapes are also affected. This can result in specific enzymes being activated (enzymes are proteins that speed up chemical reactions). These enzymes can catalyze the release of energy from ATP or other high energy molecules which power metabolic and structural changes within the cell.

A

Receptor-mediated endocytosis

92
Q

Receptor-mediated endocytosis…….

A

……Receptor proteins (integral) in a cell membrane bind with a signaling molecule sent from another cell. The signaling molecule (known in general as a ligand) is often in the form of a hormone. The receptor protein is responsible for transferring the signal across the membrane. When the ligand binds to the receptor protein, it changes the shape of the protein. Because the receptor protein is in close proximity to other proteins, their shapes are also affected. This can result in specific enzymes being activated (enzymes are proteins that speed up chemical reactions). These enzymes can catalyze the release of energy from ATP or other high energy molecules which power metabolic and structural changes within the cell.

93
Q
A
94
Q

Endocytosis is often referred to as an ______ because it requires energy.

A

active process (not to be confused with active transport)

95
Q

______ is often referred to as an active process (not to be confused with active transport) because it requires energy.

A

Endocytosis

96
Q

True or False: It should be noted that the particles within the vesicle do not actually cross the membrane until after fusion with a lysosome.

A

True

96
Q
A

Anatomy 1 (22 decks)

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