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Biology 201A > Membranes > Flashcards

Membranes Flashcards

(62 cards)

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1
Q

Selective permeability

A

Hydrophobic (nonpolar) molecules cross the membrane easily through dissolution in hydrophobic region
Hydrophilic (polar) molecules and ions do not move across easily (moved by transport proteins)

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2
Q

Types of membrane movement

A

Active transport
Passive transport
Diffusion
Facilitated diffusion

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3
Q

Active transport

A

Transport requiring energy (ATP)
Membrane pumps and carrier proteins
Moving against concentration gradient

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4
Q

Passive transport

A

No energy required
Moving with the concentration gradient

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5
Q

Diffusion

A

net movement of molecules from high to low concentration until equilibrium is reached
Spontaneous process that increases entropy

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6
Q

Facilitated diffusion

A

Channel proteins and carrier protons
Allow diffusion to occur more easily

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7
Q

Osmotic concentration

A

Total solute concentration of a solution

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8
Q

Osmotic equilibrium

A

Equal concentrations of solute on both sides
No net movement

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9
Q

Concentration gradient

A

Graded change in the concentration of a substance over some distance

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10
Q

Osmosis

A

Diffusion of water across a selectively permeable membrane

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11
Q

Tonicity

A

The ability of the surrounding solution to cause a cell to gain or loose water

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12
Q

Isotonic solution

A

Solution has the same concentration as inside of the cell

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13
Q

Hypertonic solution

A

Solution has a greater osmotic concentration than the cell

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14
Q

Hypotonic solution

A

Solution has a lower osmotic concentration than the cell

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15
Q

Isotonic solution in animals

A

Normal

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16
Q

Isotonic solution in plants

A

Flaccid

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17
Q

Hypertonic solution in animals

A

Crenulated/shriveled
Water diffuses from cell to solution

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18
Q

Hypertonic solution in plants

A

Plasmolyzed
Water diffuses out of cell
Cell membrane pulls away from the cell wall

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19
Q

Hypotonic solution in animals

A

Lysed
Water diffuses into the cell

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20
Q

Hypotonic solution in plants

A

Turgid (normal)
Water diffuses into the cell increasing turgor (water) pressure

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21
Q

Osmoregulation

A

Adaptations for the control of water balance
Contractile vacuole in protists

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22
Q

Fluid mosaic model

A

Comprised of phospholipid bilayer
Mosaic mixture of lipids, proteins, and carbohydrates
Selectively permeable
Fluidity

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23
Q

How are phospholipids held together

A

Weak hydrophobic interactions

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24
Q

Fluidity

A

The ability for components of a cell membrane to move

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25
Protein complexes
Specialized patches of proteins that travel together in the membrane
26
Lipid rafts
Specialized patches of lipids that travel together in the membrane
27
Cholesterol
Steroid imbedded in the cell membrane
28
Cholesterol function
Acts as a buffer against temperature changes Keeps the membrane
29
Saturated fatty acids
Straight chained, no double bonds, tight (non-fluid) phospholipid arrangement
30
Unsaturated fatty acids
Bent chain with double bonds, creates space for a fluid phospholipid arrangement
31
Variations in cell membrane structure
Changes membrane fluidity via lipid content and proportion of saturated vs unsaturated fatty acids as an evolutionary response to different environmental factors
32
Integral proteins
Go through the membrane
33
Transmembrane protein
Type of integral protein that crosses the entire membrane
34
Integral protein structure
Hydrophobic interior regions consisting of stretches of 20-30 amino acids in an alpha helix structure
35
Peripheral proteins
Loosely bound to the surface of the membrane or resting on integral proteins
36
Membrane protein functions
Transport Enzymatic activity Cell to cell recognition Intercellular joining Cell structure
37
Transport proteins
Provides hydrophilic channel across the membrane Proteins are very specific with what they allow through (size and charge) Channel proteins Carrier proteins Aquaporins Membrane pumps
38
Signal transduction
Process in which a cell signal is converted to a cellular response as a signaling molecule attaches to a receptor to change shape
39
Cell to cell recognition
Polysaccharides serve as tags allowing cells to recognize like cells so they develop properly and organize into tissues (recognize like cells) and provide immunity (reject unfamiliar cells)
40
Cell structure
Attachment of proteins to cytoskeleton and extracellular matrix
41
Glycoprotein
Carbohydrates with a protein
42
Glycolipids
Carbohydrates with a lipid
43
Channel proteins
Passive transport Proteins that allow molecules or ions to diffuse through the membrane
44
Ion channels
Channel proteins that transport ions
45
Gated channels
Channel proteins that open and close in response to a stimuli (chemical or electric)
46
Aquaporins function
Channel proteins that transport water
47
Aquaporins structure
Consist of 4 identical polypeptide subunits each forming a channel
48
Carrier proteins
Active and passive transport Change conformation as they move substances
49
Membrane pumps
Active transport carrier proteins
50
H⁺ pump
Pumps H⁺ out of cell to create a positively charged extracellular side which can be used for cell work Main electrogenic pump for plants, fungi, and bacteria
51
Electrogenic pump
Pump that creates a voltage difference across a membrane by redistributing ions
52
Voltage
Electrical potential energy
53
Membrane potential
Voltage across membrane Cytoplasmic side is negative in comparison to the EC side Causes certain ions to be favored in passive transport Negative cytoplasm favors positive cations
54
Electrochemical gradient
Osmotic gradient plus charge gradient that helps govern diffusion as substances always diffuse along this gradient (only sometime along only osmotic gradient)
55
Cotransport
Substance that has been pumped across the membrane can carry another substance with it as it diffuses back
56
Bulk transport
Transport across the plasma membrane that requires energy Endocytosis and exocytosis
57
Exocytosis
A large vesicle fuses with the cell membrane to move molecules to outside of cell
58
Endocytosis
Membrane forms a large vesicle around molecules outside the cell to pull them inside
59
Types of endocytosis
Phagocytosis Pinocytosis Receptor
60
Phagocytosis
Movement of particles into the cell
61
Pinocytosis
Movement of fluid into the cell via coated vesicles
62
Receptor
Mediated endocytosis Movement of specific molecules into the cell that first bind to receptors (taking in everything else but ensuring the specific molecule)

Biology 201A (15 decks)

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