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Biology > Y12 Transport Across Cell Membranes > Flashcards

Y12 Transport Across Cell Membranes Flashcards

1
Q

Phospholipid structure

A

Made up of glycerol molecule with two fatty acid chains (tails) and a hydrophilic phosphate head (polar).
The heads point to the outside of the membrane while the hydrophobic tails point to the center

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2
Q

Transport Proteins

A

Proteins embedded in the membrane that span its entire width and function as channels or carriers to allow large molecules and ions to pass though

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3
Q

Temperature effects (0.C)

A

Below 0.C, proteins can deform and ice crystals form holes in the membrane, leading to high permeability when thawed

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4
Q

Glycoproteins

A

Proteins with a polysaccharide chain attached that act as receptors and recognition sites

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5
Q

Partial permeability

A

Property of cell membranes that allows only certain molecules to pass though while restricting others

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6
Q

Cholesterol function

A

Binds hydrophobic tails together causing them to pack more closely, restricting phospholipid movement and making the membrane less fluid and more rigid

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7
Q

Ethanol function

A

Shifts lipid molecules out of place and breaks up their orderly arrangement, making the membrane more liquid-like and increasing permeability

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8
Q

Temperature effects (normal range)

A

Between 0.C and 45.C the membrane is partially permeable, with permeability increasing as temperature rises due to increased phospholipid movement

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9
Q

Temperature effect (high)

A

Above 45.C the bilayer starts to melt, water expands, and membrane proteins deform, increasing membrane permeability

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10
Q

Phospholipid bilayer

A

Basic structure of all cell membranes where phospholipids arrange in two layers with tails pointing inward and heads on the outside

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11
Q

Cell membrane composition

A

Made up of phospholipids, proteins, cholesterol, glycoproteins, and glycolipids

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12
Q

Hydrophobic center function

A

Allows lipid-soluble substances to enter and leave the cell, but prevents water soluble substances from passing through

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13
Q

Fluid Mosaic model

A

Description of membrane structure where phospholipids can move relative to one another (fluid) and proteins are embedded like tiles (mosaic)

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14
Q

Glycolipids

A

Lipids with a polysaccharide chain attached that extend into the surrounding environment, helping to stabilise the membrane and act as receptors and recognition sites

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15
Q

Membrane flexibility

A

Phospholipids make the membrane flexible and self-sealing, allowing it to change shape

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16
Q

Cell membrane function

A

Controls which substances enter and leave the cell and acts as a barrier between the cell and its environment

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17
Q

Membrane proteins function

A

Can act as transport channels, carriers, or receptors to detect chemicals released from other cells like insulin

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18
Q

Aquaporins

A

Special protein channels that allows only certain water molecules to pass through the cell membrane

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19
Q

Factors affecting permeability

A

temperature and certain solvents like ethanol can affect how permeable the cell membrane becomes

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20
Q

Membrane barrier function

A

Prevents most large molecules, polar substances, and non-lipid-soluble substances from passing through unless assisted by transport proteins

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21
Q

Haemolysis

A

The bursting of red blood cells when placed in a solution of higher water potential than the cytoplasm, causing water to move into the cell by osmosis

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22
Q

Pure water potential

A

0kPa, which is the highest water potential possible

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23
Q

Water movement in osmosis

A

Always occurs down the water potential gradients, from higher (less negative) to lower (more negative) water potential

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24
Q

Plasmolysis

A

The shrinking of a plant cell vacuole and pulling away of cytoplasm from the cell wall when placed in a solution with lower water potential than its cytoplasm

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25
Effect of Osmosis on Plant Cells in Hypertonic Solution
Cell becomes plasmolysed as water moved out, causing the cytoplasm to pull away from the cell wall
26
Partially permeable membrane
A membrane which allows smaller particles to pass through, but larger molecules cannot
27
Factors Affecting Rate of Osmosis - Surface Area
The larger the surface area, the faster the rate of osmosis
28
Effect of Osmosis on Red Blood cells in Hypotonic Solution
Cell swells and eventually bursts (haemolysis) due to water moving into the cell
29
Cell wall Function in Plants
Prevents plant cells from bursting when they become turgid due to osmosis
30
Factors affecting rate of osmosis - Water Potential Gradient
The steeper the water potential gradient, the faster the rate of osmosis. The rate levels off as the gradient decreases
31
Turgid
the state of a plant cell when placed in a solution of higher water potential, causing the vacuole to swell and put pressure on the cell wall
32
Final step of Glucose Transport
Movement of glucose molecules from epithelial cells into blood by facilitated diffusion
33
Sodium-Glucose Co-Transporter
A protein that only functions when both sodium ion and glucose molecule attach to it, allowing glucose to move against its concentration gradient
34
ATP in Active Transport
Provides energy through hydrolysis, causing carrier proteins to change shape and transport molecules across the membrane
35
Villi
Structures in the ileum that increase surface area for rapid absorption of food molecules, having good blood supply and microvilli
36
Active Transport
The movement of molecules across a cell membrane from a region of lower concentration to a region of higher concentration, against the concentration gradient. Requires energy from ATP
37
Microvilli
Tiny projections on willi that further increase the surface area for absorption in the ileum
38
DNP (Dinitrophenol)
A substance that prevents oxidative phosphorylation, stopping the sodium-potassium pump and thereby preventing amino acid absorption
39
Facilitated Diffusion
Movement of molecules across a membrane down their concentration gradient through specific protein channels or carriers, requiring no ATP
40
Ileum
The final section of the small intestine where digested food molecules are absorbed into the bloodstream
41
Effect of Respiratory Inhibitors
Can prevent uptake of amino acids and glucose by stopping ATP production needed for the sodium-potassium pump
42
Sodium-Potassium pump
A specific active transport protein that actively transports sodium ions one way and potassium ions the other way across the cell membrane
43
Concentration Gradient
The difference in concentration of a substance between two areas, which drives movement in passive transport processes
44
Amino Acid Transport
Occurs through co-transport with sodium ions using an amino acid-sodium cotransporter protein, similar to glucose transport
45
Glucose Co-transport Process
Process where glucose molecules are transported to epithelial cells along with sodium ions using a sodium-glucose co-transporter protein
46
Factors affecting Active Transport Rate
-Number of carrier proteins -Speed of carrier proteins -Rate of respiration/ATP availability in the cell
47
Co-Transport
A method of transport where carrier proteins bind two molecules at once, using the concentration gradient of one molecule to move the other molecule against its concentration gradient
48
Role of Na+/K+ Pump in absorbtion
Actively transports sodium ions out of epithelial cells into blood, maintaining a low sodium concentration in epithelial cells to drive co-transport
49
Carrier Proteins in Active Transport
Specific proteins that bind to particular molecules for transport across membranes. They change shape when ATP is hydrolyzed to move molecules across the membrane
50
Epithelium
The lining tissue of the ileum, only one cell thick, through which absorbed molecules must pass
51
Lumen
The hole down the middle of the tubular ileum where products of digestion travel through
52
Temperature effect of diffusion
Higher temperature increases diffusion rate because molecules have more kinetic energy and move faster
53
Limiting factor
Factor that prevents any further increase in the rate of a process, such as when transport proteins become saturated in facilitated diffusion
54
Facilitated diffusion graph pattern
Shows initial increase in rate with concentration but then plateaus when transport proteins become saturated
55
Non-diffusible Molecules
Molecules that cannot pass through simple diffusion due to being either not lipid-soluble, too large, or polar
56
Carrier Proteins
Transport proteins that move large molecules across the membrane by binding to them, changing shape, and releasing them on the other side
57
Channel proteins
Proteins that form pores in the membrane for charged particles to diffuse through, specific to particular molecules or ions they transport
58
Factors affecting simple diffusion rate
-Distance/Thickness of exchange surface -Surface Area -Temperature -Concentration Gradient
59
Simple Diffusion
Process where small molecules like oxygen and carbon dioxide can diffuse straight through the cell-surface membrane by passing between phospholipids, requiring no energy/ATP
60
Protein Saturation
When all transport proteins in a membrane are in use and become a limiting factor, preventing any increase in the rate of facilitated diffusion
61
Equilibrium
State reached when concentrations are equal on both sides of the membrane and net diffusion stops
62
Simple Diffusion Graph Pattern
Shows a direct proportional relationship between external concentration and rate of diffusion
63
Factors affecting facilitated diffusion rate
-Surface area -Temperature -Concentration gradient -Number of channel/carrier proteins
64
Water diffusion
Special case where despite being polar, water molecules can diffuse by simple diffusion due to their small size fitting between phospholipids
65
Passive transport
Movement of molecules that requires no energy or ATP input
66
Concentration Gradient
The difference in concentration between two areas, molecules move from where there is a high concentration to where there is a lower concentration
67
Phospholipid Bilayer
The main structure of cell membranes that small non-polar molecules can pass through but blocks large or polar molecules
68
Surface Area effect
LArger surface area increases diffusion rate because more molecules can diffuse across simultaneously
69
Diffusion
The net movement of molecules or ions from an area where they are more highly concentrated to one where their concentration is lower until evenly distributed
70
Cellular adaption for transport
Cells can adapt for rapid transport by increasing the number of protein channels and carrier molecules in their membranes
71
Facilitated diffusion
Movement of molecules or ions through channel and carrier proteins in the membrane, occurring down a concentration gradient without requiring ATP
72

Biology (10 decks)

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