6: Cell Membranes Flashcards

Module 1, Lesson 6

1
Q

All plasma membranes contain…

A

Lipids and proteins

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2
Q

____ are a fundamental structure in plasma membranes.

A

Phospholipids

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3
Q

____ on the outer surface of the membrane create a sugar coat (glycocalyx).

A

Carbohydrates

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4
Q

What are the functions of the glycocalyx?

(three)

A
  1. Protects the cell
  2. Helps the cell interact with other cells
  3. Helps other cells recognize the cell
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5
Q

Phospholipids are composed of a ____ head group and two ____ tails.

A

Hydrophilic head group
Hydrophobic tails

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6
Q

The tails of phospholipids are long chains of…

A

Fatty acids

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7
Q

Phospholipids that connect fatty acids to a phosphate group using glycerol are called…

A

Glycerol phospholipids

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8
Q

True or false:

Cells can control the length of a phospholipid’s fatty acid tail.

A

True

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9
Q

A fatty acid that contains double bonds is considered…

A

Unsaturated

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10
Q

A fatty acid that does not contain double bonds is considered…

A

Saturated

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11
Q

In water, phospholipids associate into structures such as the…

(two)

A

Micelle and bilayer

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12
Q

A spherical structure where the head groups are on the outside is called a…

A

Micelle

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13
Q

A continuous sheet with two outside edges made up of head groups is called a…

A

Bilayer

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14
Q

List the three types of monolayers.

A

Faces, leaflets, surfaces

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15
Q

Phospholipid bilayers give the cell membrane its property of…

A

Selective permeability

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16
Q

Which types of molecules can freely cross the plasma membrane?

A

Small and nonpolar (hydrophobic)

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17
Q

Which types of molecules can only cross the plasma membrane slowly?

A

Polar, hydrophilic

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18
Q

The ____ model of the plasma membrane visualizes it as a 2D fluid where proteins are either inserted or dissolved.

A

Fluid mosaic

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19
Q

The two main types of proteins in the plasma membrane are…

A

Integral proteins and peripheral proteins

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20
Q

____ is a lipid inserted into the bilayer that enhances barrier properties.

A

Cholesterol

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21
Q

Phospholipids and proteins can diffuse ____ in membranes.

A

Laterally

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22
Q

Phospholipids and proteins are able to diffuse in membranes due to…

A

Weak hydrophobic interactions

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23
Q

List three things that can reduce the fluidity of the plasma membrane.

A
  1. Lower temperatures
  2. Longer fatty acid tails
  3. Saturated fatty acid tails
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24
Q

Cells can reduce the affinity of phospholipids for each other by…

A

Adjusting the length of the tails or the number of bonds in the tails

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25
Q

Proteins embedded in the phospholipid bilayer are called the…

A

Integral membrane proteins

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26
Q

True or false:

We can isolate integral membrane proteins without destroying the membrane.

A

False

Because the proteins are embedded in the bilayer, isolating them requires destroying the membrane.

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27
Q

Proteins that pass through the bilayer and are exposed on each side of it are called…

A

Transmembrane proteins

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28
Q

Transmembrane proteins with only one transmembrane domain are called…

A

Single-pass proteins

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29
Q

Transmembrane proteins with multiple transmembrane domains are called…

A

Multi-pass proteins

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30
Q

Proteins that are attached to lipids or fatty acids are called…

A

Lipid anchor proteins

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31
Q

Transmembrane proteins and lipid anchor proteins are types of…

A

Integral membrane proteins

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32
Q

True or false:

A single lipid anchor protein is only found on one side of the bilayer or another.

A

True

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33
Q

Proteins that are noncovalently bound to transmembrane proteins or phospholipid heads are called…

A

Peripheral membrane proteins

34
Q

True or false:

Peripheral membrane proteins can be removed from the membrane without destroying it.

A

True

35
Q

True or false:

Membrane faces are asymmetric.

A

True

36
Q

The faces of a membrane differ in…

A

Composition and function

37
Q

Carbohydrates are only found on the ____ face of the plasma membrane.

A

Outer

38
Q

The inner face of the plasma membrane is also called the ____ face.

A

Intracellular

39
Q

The outer face of the plasma membrane is also called the ____ face.

A

Extracellular

40
Q

____ proteins detect signal molecules and initiate a response.

A

Receptor

41
Q

____ proteins allow a cell to be recognized by other cells.

A

Cell identity

42
Q

____ promote a specific chemical reaction.

A

Enzymes

43
Q

____ proteins help cells attach to one another.

A

Cell adhesion

44
Q

____ proteins transmit changes in the cytoskeleton to changes in the membrane.

A

Cytoskeletal attachment

45
Q

____ proteins facilitate movement of small molecules across the plasma membrane.

A

Transport

46
Q

____ can be used to move molecules across the membrane that cannot cross by themselves.

A

Transport proteins

47
Q

Transport proteins are present in both ____ and ____ membranes.

A

Plasma and organelle

48
Q

____ create a pore in the membrane to let certain molecules (often ions) cross.

A

Channel proteins

49
Q

Channel proteins move molecules using…

A

Passive transport

50
Q

Channel proteins that can open or close in response to a signal are called…

A

Gated channel proteins

51
Q

True or false:

Some channel proteins will only allow a specific molecule to cross the membrane.

A

True

52
Q

____ can use passive transport to carry out facilitated diffusion.

A

Carrier proteins

53
Q

Carrier proteins work by…

A

Bonding to a molecule, then reversing shape to allow it into the cell

54
Q

True or false:

A single carrier protein can transport multiple types of molecules.

A

False

Each carrier protein is specific to a certain molecule.

55
Q

True or false

Carrier proteins can engage in both active and passive transport.

A

True

56
Q

Most carrier proteins engaged in active transport are considered…

A

ATPases

57
Q

ATPases power movement using energy from…

A

ATP hydrolysis

58
Q

____ uses ion gradients as its energy source.

A

Coupled transport

59
Q

What are the two types of molecules involved in coupled transport?

A

Symporters and antiporters

60
Q

____ move both the ion and a molecule in the same direction.

A

Symporters

61
Q

____ move a molecule in the opposite direction from an ion.

A

Antiporters

62
Q

Most coupled transporters are located in the ____ and move molecule using the ____ gradient.

A

Plasma membrane ; sodium

63
Q

The movement of water down its concentration gradient is known as…

A

Osmosis

64
Q

Water molecules will naturally move to an area with…

A

Higher solute concentration

65
Q

The force needed to stop osmosis from occurring is called…

A

Osmotic pressure

66
Q

A solution in which solute concentration is equal on both sides of the plasma membrane is…

A

Isotonic

67
Q

A solution in which there is a greater solute concentration outside the cell is…

A

Hypertonic

68
Q

A solution in which there is greater solute concentration inside the cell is…

A

Hypotonic

69
Q

In an animal cell in an isotonic solution…

A

Water goes in and out of the cell at the same rate.

70
Q

In an animal cell in a hypertonic solution…

A

Water leaves the cell, causing it to shrivel

71
Q

In an animal cell in a hypotonic solution…

A

Water rushes into the cell, causing it to burst

72
Q

In plant cells, the ____ prevents the cell from bursting.

A

Cell wall

73
Q

In a plant cell in a hypotonic solution…

A

Water pushes the membrane against the cell wall, creating a normal turgid cell

74
Q

In a plant cell in an isotonic solution…

A

The cell becomes a weaker (flaccid) cell.

75
Q

In a plant cell in a hypertonic solution…

A

The membrane shrinks back from the cell wall, causing the cell to shrivel

76
Q

Eukaryotic cells can ingest large materials from the extracellular environment using…

A

Endocytosis

77
Q

During endocytosis…

A

The plasma membrane buds inward to collect macromolecules or entire cells

78
Q

What are the three types of endocytosis?

A
  1. Pinocytosis (cell drinking)
  2. Receptor-mediated endocytosis
  3. Phagocytosis (cell eating)
79
Q

Eukaryotes internalize macromolecules and water molecules using…

A

Pinocytosis

80
Q

During pinocytosis…

A

Portions of the membrane constantly bud inward, collecting nearby macromolecules at random.

81
Q

Eukaryotes are able to recognize and consume specific macromolecules using…

A

Receptor-mediated endocytosis

82
Q
A