Membranes Flashcards
Why are all cell membranes the same thickness?
AND therefore what do we say instead of the cell membrane being ‘thin’ and therefore being fast for diffusion?
Because they are made up of the phospholipid bilayer.
You would say there is a short diffusion distance pathway when the substance moves between the cell membrane of one cell to the other and that it is 1 cell thick.
2 advantages of cell membranes that allow rapid transport.
-Can be adapted for rapid transport across them by having lots of protein carriers and channels/or co-transport carriers
-The membrane can be folded so it has a larger Surface area (SA) for rapid transport
How is the water potential affected after eating a meal?
After a meal lots of glucose is absorbed into the blood this lowers the water potential which means that water will move from cells into the blood and
the blood vessels will burst, and the cells will die because they need the water that has moved out for metabolic reactions such as hydrolysis and condensation reactions. Therefore this glucose if it gets too much and water starts to move into the blood vessels in excess and so the cells lose water and die, the glucose will be stored as glycogen which is not lipid soluble and so does not affect the water potential so cannot pass through membranes or create a good enough concentration gradient for water to move in or out.
We release insulin from pancreas when we have too much glucose in the blood and insulin remove glucose from the blood and put it in the liver and muscle cells when glucose gets too high in the cells it is transferred into glycogen which is not lipid soluble so does not affect the water potential
What does buffer solution do?
The buffer solution controls the pH in a test tube to make sure it stays at the correct pH
What does cyanide do to affect transport?
Inhibits respiration so no production of ATP occurs and therefore no active transport can take place
For example: (so no Na+ ions moving up the concentration gradient in co-transport)
What must substances be to pass through the phospholipid bilayer?
Must be small and lipid soluble so that they can pass through the phospholipid bilayer.
What is the highest water potential for water?
zero
When glucose is added to water what happens to the water potential ?
Glucose is added or a soluble substances added
so water attaches to the glucose cause it is soluble in water
so water is no longer free and the water potential is lowered to the negatives not zero
Effect of honey at killing bacteria on a cut? use knowledge of water potentials?
Bacteria in a coat has a water potential
so honey lowers the water potential around the bacteria because it contains glucose, the glucose in the honey is released and so the water potential is lowered.
Water in the bacteria will move out of the bacterial pathogen via osmosis from the high-water potential to the lower water potential in the honey.
Bacteria will die because they cannot do metabolic reactions such as hydrolysis and condensation because they do not have water.
