1. separates cell's components from the external environment 2. regulates transport in and out of cells 3. can contain enzymes involved in metabolic pathways 4. has antigens 5. help with cell to cell signalling 6. site of chemical reactions 7. drugs
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what are the 3 uses of membranes within cells?
1. mitochondria have cristae that give large surface area for respiration 2. chloroplasts have thykaloids that house chlorophyll; photosynthesis occurs here 3. some membranes can form to make vesicles to send ot the golgi
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what do instrinsic proteins do?
act as pores and channels to allow ions to pass thorugh
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what do carrier proteins do?
they perform a conformational change and carry specific molecules across the membrane
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what does cholesterol do to the membrane
regulates fluidity and maintains the mechanical stability as well as resisting changes in temperature
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what is an aqua porin?
a specific channel for the movement of water through a membrane
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what type of molecules can pass through the plasma membrane
non-polar molecules
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what is simple diffusion
when molecules move down their concentration gradient
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what five factors affect the rate of diffusion
temperature, diffusion distance, surface area, size of diffusing molecules and concentration gradient
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what is the definition of osmosis?
the passage of water molecules down their water potential gradient across a partially permeable membrane
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what is the definition of water potential
a measure of the tendency of water molecules to diffuse form one region to another
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what is cytolysis
when water enters an animal cell and the membrane breaks
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what is turgidity
when water enters an plant cell but the cellulose cell wall prevents bursting
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what happens when an animal cell shrivels
the cell is crenated
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what happens when a pllant cells shirvels
they are plasmolysed
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what is active transport
when cells need to move against the concentration gradient
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what do carrier proteins do?
have sites that combine with only certain ions. they perform a conformational change
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what is endocytosis
large molecules are brought into the cell
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what is exocytosis
large molecules are exported out of the cell
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what factors affect membrane structure and permeability?
temperature
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what are the four effects of decreasing temperature on phospholipids?
1. saturated fatty acids become compressed 2. the unsaturated fatty acids have kinks that push the adjacent molecules away 4. cholesterol in the membrane buffer the effects of low temp by preventig the phospholipids from packing too close
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what are the 5 effects of increasing temperature on phospholipids?
fill in blank
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how does an increase in temperature affect proteins?
high temperatures cause the atoms to vibrate, hydrogen and ionic bonds break. so the structure unfolds. the tertiary structure changes permanently and they are denatured
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what is the effect of solvents on phospholipids?
organic solvents damage cell membranes as they are non-polar
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Other cards in this set
Card 2
Front
what are the 3 uses of membranes within cells?
Back
1. mitochondria have cristae that give large surface area for respiration 2. chloroplasts have thykaloids that house chlorophyll; photosynthesis occurs here 3. some membranes can form to make vesicles to send ot the golgi
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