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36 Cards in this Set
- Front
- Back
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Function of a cell surface membrane? |
Barrier between cell and its environment, controlling what comes in and out |
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What are membranes made up of? |
Lipids, proteins and glycoproteins, glycolipids |
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Describe the fluid mosaic model? |
Fluid because the phospholipids are constantly moving and mosaic because of the way the proteins are scattered through the bilayer like a mosaic |
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Describe a phospholipid? |
Barrier to water soluble substances Hydrophilic head and a hydrophobic tail In a bilayer Does not allow water soluble substances like ions and polar molecules |
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What does cholesterol do in a phospholipid bilayer? |
Gives the membrane stability It binds to the hydrophobic tail and causes them to pack closely together, makes the membrane more rigid |
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What does cholesterol do in a phospholipid bilayer? |
Gives the membrane stability It binds to the hydrophobic tail and causes them to pack closely together, makes the membrane more rigid |
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What happens to membranes in a temperature below 0 degrees? |
Dont have much energy so they don’t move as much, therefore they pack closer together, channel proteins and carrier proteins denature , increasing permeability, ice crystals may form and pierce the membrane making it even more permeable |
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Definition of diffusion? |
Net movement of particlrs from an area of high concentration to an area of low concentstion |
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Is diffusion a passive process? |
Yes |
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What factors affect the rate of diffusion? |
How high a concentration graduent is Thickness of the exchange surface Surface area |
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Why does facillitated diffusion happen? |
Large molecules diffuse slowly through and charge particles because they are water soluble diffuse slowly |
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What helps facilitated diffusion happen? |
Carrier proteins and channel proteins |
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Is facilitated diffusion a passive process? |
Yes |
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How do carrier proteins work? |
Large molecule attaches Protein changes shape Then releases it on the other side |
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How do carrier proteins work? |
Large molecule attaches Protein changes shape Then releases it on the other side |
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How do channel proteins work? |
Charged particle diffuses down its concentration gradient across the channel |
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Factors affecting the rate of facilitated diffusion? |
Height of the concentration gradient Number of channel or carrier proteins |
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Definition of osmosis? |
Diffusion of water molecules across a partially permeable membrane from an area of high water potential to an area of low water potential |
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Definition of osmosis? |
Diffusion of water molecules across a partially permeable membrane from an area of high water potential to an area of low water potential |
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Definition of water potential? |
Is the likelihood of water molecules to diffuse in or out of a solution |
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What is the water potential of pure water? |
Zero |
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What is the water potential of pure water? |
Zero |
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What happens if you add a solute to pure water? |
Water potential becomes negative |
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What is an isotonic solution? |
Two solutions with the same water potential |
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What is an hypotonic solution? |
Solution with a higher potential than the cell, cell will swell |
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What is a hypertonic solution? |
Lower water potential than the cell Cell will shrink |
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Factors affecting rate of osmosis? |
Water potential gradient Thickness of exchange surface Surface area |
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What is a serial dilution? |
Create a set of solutions that decrease in concentration by the same factor each time |
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How to make a serial dilution? |
1. Line uo 5 test tubes 2. Add 10cm3 of the 2M sucrose solution to the first test tube and 5cm3 of distilled water to the others. 3. Then using a pippette draw 5cm3 of the solution and add it to the next one. Now have 10cm3 of the solution, so now that one is 1M 4.repeat the process three more times to create solutions of 0.5M,0.25M,0.125M |
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How to work out the scale factor? |
Concentration of the solution/concentration od the solution you want to make |
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How to calculate the percentage change in mass in the potato chips? |
1. Use a cork borer to cut potato into identically sized chips. Measure mass. 2. Place one group into each sucrose solution for 20 mins. 3.remove chips and pat dry. Weigh each group and calc percentage change. |
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What to do after you have weighed the potato chips a second time? |
Produce a calibration curve by plotting percentage change in mass against concentration |
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Differences between active transport and facilitated diffusion? |
Active transports moves solutes from low to high concentrations, whereas facilitated high to low Active transport needs energy |
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What do co transporters do? |
Bind two molecules and use the concentration gradient of one to move the other molecule agaisnt its own |
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Explain the absorption of glucose? |
Na+ are actively transported out of epithelial cells in to the blood, this creates a conc gradient of sodium ions This causes Na+ to diffuse into the epithial cells. The sodium-glucose co transporter carries glucose into the cell aswell. As a result conc of glucose inc Glucose then diffuses into the blood |
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Factors affceting rate of active transport? |
Speed of carrier proteins Number of carrier proteins Rate of respiration |
