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MCAT > 2A: Assemblies of molecules, cells and groups of cells within single cellular and multicellular organisms > Flashcards

2A: Assemblies of molecules, cells and groups of cells within single cellular and multicellular organisms Flashcards

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MCAT flashcards
1
Q

Plasma Membrane

A

Functions to contain the cell structures and protects them from the environment

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2
Q

Plasma Membrane

A

Functions to contain the cell structures and protects them from the environment

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3
Q

Composition of Plasma Membrane

A

Phospholipid Bilayer that can reseal and repair itself if a small portion is removed;
Interior = hydrophobic, nonpolar molecules like CO2 or O2 or Steroid Hormones can easily cross
Exterior = hydrophilic

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4
Q

How does water cross the plasma membrane?

A

Water passes through aquaporins in order to get through the membrane since its polar

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5
Q

How do ions, carbohydrates and amino acids get through the membrane?

A

They utilize special channels or transport proteins

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6
Q

Channel Proteins

A

Selective to certain ions/molecules that need to cross the membrane

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7
Q

How do ions, carbohydrates and amino acids get through the membrane?

A

They utilize special channels or transport proteins

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8
Q

Fluid Mosaic Model

A

Accounts for the presence of lipids, proteins and carbohydrates in a dynamic, semisolid plasma membrane that surrounds cells

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9
Q

Phospholipid Bilayer

A

Contains proteins embedded within the plasma membrane

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10
Q

Phospholipid Bilayer

A

Contains proteins embedded within the plasma membrane

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11
Q

Membrane Dynamics

A

The free movement of lipids forming lipid rafts, Flippases that maintain bidirectional transport of lipids between the two layers of the phospholipid bilayer

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12
Q

Movement of Protein & Carbohydrates

A

Move within the membrane but are slowed by their relatively large size

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13
Q

Movement of Protein & Carbohydrates

A

Move within the membrane but are slowed by their relatively large size

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14
Q

Movement of Protein & Carbohydrates

A

Move within the membrane but are slowed by their relatively large size

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15
Q

Membrane Components [Lipids]

A

Triacylglycerols & Free Fatty Acids
Glycerophospholipids
Cholesterol
Waxes

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16
Q

TAG & FFA

A

Act as phospholipid precursors and are found in low levels in the membrane

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17
Q

Cholesterol

A

Present in large amounts and contributes to membrane fluidity and stability

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18
Q

Waxes

A

They function in waterproofing and defense

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19
Q

Waxes

A

They function in waterproofing and defense

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20
Q

Function of Proteins in the Cell Membrane

A

Transports, Cell Adhesion Molecules and Enzymes

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21
Q

Transmembrane Proteins

A

Can have one or more hydrophobic domains and are most likely to function as receptors or channels

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22
Q

Embedded Proteins

A

Usually part of a catalytic complex or involved in cellular communication

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23
Q

Embedded Proteins

A

Usually part of a catalytic complex or involved in cellular communication

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24
Q

Membrane-Associated Proteins

A

Act as recognition molecules or enzymes

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25
Q

Glycoprotein Coat

A

Carbohydrates that form a protective coat and functions in cell recognition

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26
Q

Glycoprotein Coat

A

Carbohydrates that form a protective coat and functions in cell recognition

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27
Q

Cell-Cell Junctions

A

Regulate transport intracellularly and intercellularly;

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28
Q

Types of Cell-Cell Junctions

A

Gap Junctions, Tight Junctions, Desmosomes and Hemidesmosomes

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29
Q

Types of Cell-Cell Junctions

A

Gap Junctions, Tight Junctions, Desmosomes and Hemidesmosomes

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30
Q

Dominance of Biomolecules in the Lipid Membrane

A

Lipids > Proteins > Carbohydrates > Nucleic Acids

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31
Q

Examples of Phospholipids

A

Lecithin, Phosphatidylinositol

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32
Q

Examples of Sphingolipids

A

Ceramides, Sphingomyelins, Cerebrosides, Gangliosides

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33
Q

Cholesterol

A

Present in large amounts and contributes to membrane fluidity and stability; necessary for steroid synthesis

34
Q

Embedded (Integral) Proteins

A

Usually part of a catalytic complex or involved in cellular communication

35
Q

Membrane-Associated (Peripheral) Proteins

A

Act as recognition molecules or enzymes

36
Q

Examples of Sphingolipids

A

Ceramides, Sphingomyelins, Cerebrosides, Gangliosides

37
Q

Gap Junctions (Connexons)

A

Allow for cell-cell communication; groups of connexin form these; permit movement of water and some solutes directly between cells

38
Q

Gap Junctions (Connexons)

A

Allow for cell-cell communication; groups of connexin form these; permit movement of water and some solutes directly between cells

39
Q

Tight Junctions

A

Prevent solutes from leaking into the space between cells via a paracellular route

40
Q

Tight Junctions

A

Prevent water and solutes from leaking into the space between cells via a paracellular route

41
Q

Tight Junctions

A

Prevent water and solutes from leaking into the space between cells via a paracellular route

42
Q

Desmosomes

A

Bind adjacent cells by anchoring to their cytoskeleton; they are associated with intermediate filaments; primarily found between two layers of epithelial tissue

43
Q

Hemidesmosomes

A

Attach epithelial cells to basement membranes

44
Q

How do concentration gradients aid in solute transport across membranes?

A

Help determine appropriate membrane transport mechanisms in cells

45
Q

How does osmotic pressure aid in solute transport across membranes?

A

It is pressure applied to a pure solvent to prevent osmosis and is used to express the concentration of the solution;

46
Q

Passive Transport [-dG]

A

It’s a spontaneous process because the molecule is moving down its concentration gradient from an area of higher concentration to an area of lower concentration

47
Q

Types of Passive Transport

A

Simple Diffusion
Osmosis
Facilitated Diffusion

48
Q

Simple Diffusion

A

Does not require a transporter; small nonpolar molecules utilize simple diffusion until equilibrium is achieved

49
Q

Osmosis

A

Water moves from areas of dilution to areas of concentration

50
Q

Osmosis

A

Water moves from areas of dilution (high water) to areas of concentration (low water); through a selectively permeable membrane

51
Q

Osmosis

A

Water moves from areas of dilution (high water) to areas of concentration (low water); through a selectively permeable membrane

52
Q

Hypotonic Solution

A

Causes a cell to swell as water rushes in; solution is less concentrated than the cell

53
Q

Hypertonic Solution

A

Causes a cell to shrink as water rushes out

solution is more concentrated than the cell

54
Q

Isotonic Solution

A

Causes nothing to happen because the solution and the cell have the same concentration

55
Q

Isotonic Solution

A

Causes nothing to happen because the solution and the cell have the same concentration

56
Q

Facilitated Diffusion

A

Uses transport proteins to move impermeable solutes across the cell membrane; energy barrier is too high for these molecules to cross freely; ion channels, ligand gated and voltage gated channels

57
Q

Facilitated Diffusion

A

Uses transport proteins to move impermeable solutes across the cell membrane; energy barrier is too high for these molecules to cross freely; ion channels, ligand gated and voltage gated channels

58
Q

Active Transport

A

Results in the net movement of a solute against its concentration gradient; requires energy usually in the form of ATP

59
Q

Types of Active Transport

A

Primary Transport

Secondary Transport

60
Q

Primary Active Transport

A

Uses ATP to directly transport molecules across a membrane; involves use of a transmembrane ATPase

61
Q

Secondary Active Transport [Coupled Transport]

A

It harnesses energy released by one particle going down its electrochemical gradient to drive a particle up its electrochemical gradient

Symport = both particles move in the same direction across the membrane

Antiport = particles move in opposite directions

62
Q

Secondary Active Transport [Coupled Transport]

A

It harnesses energy released by one particle going down its electrochemical gradient to drive a particle up its electrochemical gradient

Symport = both particles move in the same direction across the membrane

Antiport = particles move in opposite directions

63
Q

Primary Active Transport in the Body

A

Occurs in neurons to maintain membrane potential

64
Q

Secondary Active Transport in the Body

A

Occurs in the kidneys to drive reabsorption and secretion of various solutes into and out of the filtrate

65
Q

Osmosis

[H2O]

A

Water moves from areas of dilution (high water) to areas of concentration (low water); through a selectively permeable membrane

66
Q

Facilitated Diffusion

[Polar molecules, Ions]

A

Uses transport proteins to move impermeable solutes across the cell membrane; energy barrier is too high for these molecules to cross freely; ion channels, ligand gated and voltage gated channels

67
Q

Active Transport

[Polar molecules or Ions]

A

Results in the net movement of a solute against its concentration gradient; requires energy usually in the form of ATP

68
Q

Secondary Active Transport in the Body

A

Occurs in the kidneys to drive reabsorption and secretion of various solutes into and out of the filtrate

69
Q

Sodium/Potassium Pump Solutes

[Na/K ATPase]

A

3 Na out
2 K in
1 ATP hydrolyzed

70
Q

Potassium Leak Channels

A

K flows down its gradient out of the cell and helps maintain osmotic balance with surroundings

71
Q

Where are sodium concentrations higher?

A

Outside the cell

72
Q

Where are potassium concentrations higher?

A

Inside the cell

73
Q

Where are chloride concentrations higher?

A

Outside the cell

74
Q

Where are calcium concentrations higher

A

Outside the cell

75
Q

Where are calcium concentrations higher?

A

Outside the cell

76
Q

Where are calcium concentrations higher?

A

Outside the cell

77
Q

How is membrane potential maintained?

A

By the action of the sodium potassium pump and leak channels

78
Q

How is membrane potential maintained?

A

By the action of the sodium potassium pump and leak channels

79
Q

Endocytosis

A

Occurs when the cell membrane invaginates and engulfs material to bring it into the cell; consists of Pinocytosis, Phagocytosis

80
Q

Pinocytosis

A

Ingestion of fluids and dissolved particles

81
Q

Phagocytosis

A

Ingestion of large solids such as bacteria

82
Q

Exocytosis

A

Secretory vesicles fuse with the membrane and release material to the extracellular environment

MCAT (31 decks)

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