biological membranes Flashcards
describe the effect of a high temperature on the tructure of yeast cell membranes (4)
- phospholipids vibrate due to increased kin en
- = more gaps between PHOSL
- bilayer = more fluid
- glycoproteins denature
which component of a cell membarne becomes more fluid as temperature increases ? (1)
phospholipid bilayer
what 2 mechanisms do specific membrane proteins account for the ebolity for the membrane to allow them ? (2)
- passive
- active transport
state what is meant by cell signalling (1)
communication between cells
explain how the cell surface membrane contributes to the process of cell signalling (5)
- release of messenger molecule by exocytosis
- glycoproteins act as receptors
- receptor is specific
- shape of receptor and signal are complementary
- attachment of messenger molecule causes change
state 3 roles of membranes inside cells (3)
- site for attachement of enzymes
- creation of conc gradient
- vesicles AS COMPARTEMENTS
outline how vesicles are moved from one organelle to another (4)
- cytoskeleton provide pathway
- vesicles move along microtubule
- microtubule broken down
- uses ATP
explain what is meant by active transport (3)
- movement of substances againt conc gradient
- using ATP
- using a carrier protein
state 2 examples of active transport into cells (2)
- nitrate ions into root hair cells
- H+ ions out of companion cells
describe the routes that water molecules take through the cell surface membrane (2)
- fits between phospholipids
- via protein channels
explain why plant cells do not burst when they are left in pure water (3)
- cell wall
- provides stregth
- limits uptake of water
how ould student make resuls more accurate and reliable
1. take strips of epidermus from onion
2. place in water and range of sucrose solutions
3. leave for 30mins
4. view under high power microscope
- R = identify and ignore anomalour result
- calculate mean
- A = smaller gaps between conc
- take photographs and mark cells as counting
