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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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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
Glycoprotein Coat
Carbohydrates that form a protective coat and functions in cell recognition
26
Glycoprotein Coat
Carbohydrates that form a protective coat and functions in cell recognition
27
Cell-Cell Junctions
Regulate transport intracellularly and intercellularly;
28
Types of Cell-Cell Junctions
Gap Junctions, Tight Junctions, Desmosomes and Hemidesmosomes
29
Types of Cell-Cell Junctions
Gap Junctions, Tight Junctions, Desmosomes and Hemidesmosomes
30
Dominance of Biomolecules in the Lipid Membrane
Lipids > Proteins > Carbohydrates > Nucleic Acids
31
Examples of Phospholipids
Lecithin, Phosphatidylinositol
32
Examples of Sphingolipids
Ceramides, Sphingomyelins, Cerebrosides, Gangliosides
33
Cholesterol
Present in large amounts and contributes to membrane fluidity and stability; necessary for steroid synthesis
34
Embedded (Integral) Proteins
Usually part of a catalytic complex or involved in cellular communication
35
Membrane-Associated (Peripheral) Proteins
Act as recognition molecules or enzymes
36
Examples of Sphingolipids
Ceramides, Sphingomyelins, Cerebrosides, Gangliosides
37
Gap Junctions (Connexons)
Allow for cell-cell communication; groups of connexin form these; permit movement of water and some solutes directly between cells
38
Gap Junctions (Connexons)
Allow for cell-cell communication; groups of connexin form these; permit movement of water and some solutes directly between cells
39
Tight Junctions
Prevent solutes from leaking into the space between cells via a paracellular route
40
Tight Junctions
Prevent water and solutes from leaking into the space between cells via a paracellular route
41
Tight Junctions
Prevent water and solutes from leaking into the space between cells via a paracellular route
42
Desmosomes
Bind adjacent cells by anchoring to their cytoskeleton; they are associated with intermediate filaments; primarily found between two layers of epithelial tissue
43
Hemidesmosomes
Attach epithelial cells to basement membranes
44
How do concentration gradients aid in solute transport across membranes?
Help determine appropriate membrane transport mechanisms in cells
45
How does osmotic pressure aid in solute transport across membranes?
It is pressure applied to a pure solvent to prevent osmosis and is used to express the concentration of the solution;
46
Passive Transport [-dG]
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
Types of Passive Transport
Simple Diffusion Osmosis Facilitated Diffusion
48
Simple Diffusion
Does not require a transporter; small nonpolar molecules utilize simple diffusion until equilibrium is achieved
49
Osmosis
Water moves from areas of dilution to areas of concentration
50
Osmosis
Water moves from areas of dilution (high water) to areas of concentration (low water); through a selectively permeable membrane
51
Osmosis
Water moves from areas of dilution (high water) to areas of concentration (low water); through a selectively permeable membrane
52
Hypotonic Solution
Causes a cell to swell as water rushes in; solution is less concentrated than the cell
53
Hypertonic Solution
Causes a cell to shrink as water rushes out | solution is more concentrated than the cell
54
Isotonic Solution
Causes nothing to happen because the solution and the cell have the same concentration
55
Isotonic Solution
Causes nothing to happen because the solution and the cell have the same concentration
56
Facilitated Diffusion
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
Facilitated Diffusion
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
Active Transport
Results in the net movement of a solute against its concentration gradient; requires energy usually in the form of ATP
59
Types of Active Transport
Primary Transport | Secondary Transport
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Primary Active Transport
Uses ATP to directly transport molecules across a membrane; involves use of a transmembrane ATPase
61
Secondary Active Transport [Coupled Transport]
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
Secondary Active Transport [Coupled Transport]
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
Primary Active Transport in the Body
Occurs in neurons to maintain membrane potential
64
Secondary Active Transport in the Body
Occurs in the kidneys to drive reabsorption and secretion of various solutes into and out of the filtrate
65
Osmosis | [H2O]
Water moves from areas of dilution (high water) to areas of concentration (low water); through a selectively permeable membrane
66
Facilitated Diffusion | [Polar molecules, Ions]
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
Active Transport | [Polar molecules or Ions]
Results in the net movement of a solute against its concentration gradient; requires energy usually in the form of ATP
68
Secondary Active Transport in the Body
Occurs in the kidneys to drive reabsorption and secretion of various solutes into and out of the filtrate
69
Sodium/Potassium Pump Solutes | [Na/K ATPase]
3 Na out 2 K in 1 ATP hydrolyzed
70
Potassium Leak Channels
K flows down its gradient out of the cell and helps maintain osmotic balance with surroundings
71
Where are sodium concentrations higher?
Outside the cell
72
Where are potassium concentrations higher?
Inside the cell
73
Where are chloride concentrations higher?
Outside the cell
74
Where are calcium concentrations higher
Outside the cell
75
Where are calcium concentrations higher?
Outside the cell
76
Where are calcium concentrations higher?
Outside the cell
77
How is membrane potential maintained?
By the action of the sodium potassium pump and leak channels
78
How is membrane potential maintained?
By the action of the sodium potassium pump and leak channels
79
Endocytosis
Occurs when the cell membrane invaginates and engulfs material to bring it into the cell; consists of Pinocytosis, Phagocytosis
80
Pinocytosis
Ingestion of fluids and dissolved particles
81
Phagocytosis
Ingestion of large solids such as bacteria
82
Exocytosis
Secretory vesicles fuse with the membrane and release material to the extracellular environment

MCAT (31 decks)

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