How does increase in temperature affect cell membrane?
fatty acid tails have more kinetic energy-move more,increases fluidity of membrane-more permeable.At 40*C membrane proteins begin to denature-disrupt membrane & it can no longer act as an effective barrier-cell could break down completely
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How does decrease in temperature affect cell membrane?
fatty acid tails have less kinetic energy,so move around less-decreases fluidity of membrane & its permeability.Means vital molecules can't enter e.g.oxygen so metabolic reactions inside cell can't take place-cause cell damage/death
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How do organic solvents affect cell membrane?
They can dissolve the phospholipids ,disrupt the membrane-make it more fluid & permeable as the cell is no longer intact
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How do antiseptic wipes prevent infection?
These wipes contain alcohol (organic solvent), this dissolves the bacterial membranes-killing the bacteria-prevent infection
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How does drinking alcohol affect neurones?
Alcohol we drink isn't concentrated but will disrupt nerve cell's membrane & make it more fluid/permeable.As neurone is no longer intact-affects normal transmission of nerve impulses between neurones- causes typical symptoms after alcohol intake
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Diffusion
the net movement of particles from an area of high concentration to an area of low concentration
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Is diffusion active or passive transport?
Diffusion is a passive transport method cos it utilises energy from the natural motion of particles-rather than an external energy source
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Simple Diffusion
the diffusion that occurs in the abscence of a barrier/membrane
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2 Factors affecting Simple Diffusion?
Temperature & Concentration Difference
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How does temperature affect diffusion?
the higher the temp the higher the rate of diffusion because particles have more kinetic energy & move faster
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How does concentration gradient affect diffusion?
The greater the difference in the concentration gradient between 2 regions -higher rate of diffusion cos the overall movement from high to low concentration is greater
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Why is plasma membrane partially permeable?
As it only allows certain substances to enter throughe.g.non-polaror small polar molecules but prevents entry/exit of other molecules e.glarge polar/ionic molecules
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Factors affecting diffusion across membranes?
1)Surface area 2)Membrane Thickness
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How does surface area affect diffusion?
larger the area of an exchange surface,more particles can diffuse at a time=higher rate of diffusion
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How does Membrane Thickness affect diffusion?
the thinner the exchange surface,shorter the diffusion pathway=higher rate of diffusion
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Facilitated Diffusion?
Diffusion of polar & ionic molecules through channel/carrier proteins in membrane
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Factors affecting facilitated diffusion?
Concentration difference,temp,surface area,membrane thickness & number of protein channels
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Active Transport
the movement of molecules/ions into/out of a cell form a region of low concentration to high concentration-up the concentration gradient
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How does Active Transport work?
1) substance to be transported binds to receptors on carrier protein 2)inside of cell, ATP binds to protein & hydrolysed into ADP & phosphate3)Carrier protein change shape,which opens up to inside of cell cos phosphate binds to it
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How does Active Transport work?(continued)
4)substance is released to the inside of cell 5)the phosphate molecule is released from carrier protein & recombines with ADP to form ATP & protein returns to original shape
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Bulk Transport?
Form of active transport, where large substances e.g.bacterial cells,hormones,enzymes are too large to move thru channel/carrier proteins-so they are moved into/out of cells via bulk transport
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Examples of bulk transport
1)Exocytosis-bulk transport of material out of cell 2)Endocytosis-bulk transport of materials into cells e.g.Phagocytosis-for solids & Pinocytosis-Liquids
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Explain how Endocytosis works?
1)plasma membrane bends inwards when it comes into contact with material to be transported 2)Membrane enfolds material,till it fuses & forms a vesicle3)Vesicle pinches off & moves into cytoplasm to transfer material for further processing
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When is ATP required during bulk transport?
ATP is required when vesicles move along the cytoskeleton
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Other cards in this set
Card 2
Front
How does decrease in temperature affect cell membrane?
Back
fatty acid tails have less kinetic energy,so move around less-decreases fluidity of membrane & its permeability.Means vital molecules can't enter e.g.oxygen so metabolic reactions inside cell can't take place-cause cell damage/death
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