Cell Membranes Model Answers

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  • Created by: elx
  • Created on: 12-05-17 12:39
What are the components of the plasma membrane?
Phospholipids, proteins, glycoproteins, cholesterol, glycolipids
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What is the function of cholesterol?
Stabilse membrane, maintain fluidity, reduce permeability to polar and charged molecules
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What is the function of phospholipids?
Barrier to polar and charged molecules, Allow passage of small non-polar molecules, select what can enter and leave the cell
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What is the function of glycoproteins?
Antigens, recognise cells as self or non-self, cell signalling, binding site for hormones, trigger on transport proteins, cell adhesion (cells together in tissue), attch water molecules to stabilise membrane
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What is active transport?
Movement of substances against concentration gradient from low to high concentration via carrier proteins using ATP
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How does water move between cells?
By osmosis from a high to a low water potential
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What would happen if a plant cell is placed in a solution of higher water potential?
Water would move into the cell by osmosis as the cell has a lower water potential than solution, moves down the water potential gradient form high to low water potential and the cell becomes turgid
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Why does a plant cell not burst?
The cell wall provides strength asnd cn withstand intrnal pressure so the cell does not over expand, limits the uptake of water
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What would happen if a plant cell is placed in a solution of lower water potential?
Water would move out of the cell by osmosis as the cell has a lower water potential than solution, moves down the water potential gradient form high to low water potential, the cell plasmolyses
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What would happen if an animal cell is placed in a solution of higher water potential?
Water would move into the cell by osmosis as the cell has a lower water potential that the solution, moves down the watre potential gradient from a high to a low water potential, the cell burst/ indergoes cell lysis
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What would happen is an animal cell is places in a solution of lower water potential?
Water moves out of the cell by osmosis as the cell has a higher water potential that the solution, moves down the water potential gradient from a high to low water potential, the cell crenates
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How do small, non-polar substances enter the cell?
Diffuse through the phospholipid bilayer
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How do large molecules enter the cel?
Travel through a carrier proteing by facillitated diffusion
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How do polar molecules enter the cell?
Travel through channel proyeins by facillitated diffusion
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How do molecules enter a cell if they are going against the concentration gradinent?
Through specific carrier proteins by active transport which requires ATP
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How do molecules enter the cell if travelling in bulk?
By endocytosis
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How to water molecules enter a cell?
Travel between the phospholipid bilayer by channel proteins called aquaporins
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What is cell signalling?
Communication between cells, signal molecules are released from a cell by exocytosis and attaches to the receptor on the plasma membrane, the receptor and protien are specific and have complementary shapes, the bonding triggers a response in the cell
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What are the roles of membranes within cells?
Form organelles, isolate organelles, attchment site for enzymes and ribosomes, selectively permeable, create concentration gradients, control what enters or leaves the cell, isolates the DNA, form vesicles, protect the cell from hydrolytic enzymes
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What are the roles of membranes on the surface of cells?
Separate cell from environment, controll entry and exit of molecules, phospholipid bilayer = diffusion, channel/carrier proteins = facillitated diffusion, carrier proteins = active transport, endocytosis/exocytosis, receptors, microvilli
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What would happen to the plasma membrane at high temperatures?
The membrane structure is disrupted, phospholipid bilayer becomes more fluid, membrane proteins are denatured, membrane becomes more permeable
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How do roots take up minerals from the soil?
By active transport
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How are the roots specialised for their funtion?
Have extensions with thin cell walls for increased surface area, many more mitochondria and carrier proteins
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Other cards in this set

Card 2

Front

What is the function of cholesterol?

Back

Stabilse membrane, maintain fluidity, reduce permeability to polar and charged molecules

Card 3

Front

What is the function of phospholipids?

Back

Preview of the front of card 3

Card 4

Front

What is the function of glycoproteins?

Back

Preview of the front of card 4

Card 5

Front

What is active transport?

Back

Preview of the front of card 5
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