Biological Membranes Flashcards
(15 cards)
1
Q
what is the roles of membranes within cells and at the surface of cells
A
- compartmentalisation
- separates named organelles from the cytoplasm
- attachment sites for enzymes
- site of chemical reactions e.g the ETC
2
Q
describe the fluid mosaic model
A
fluid - phospholipids move freely
mosaic - proteins randomly scattered
3
Q
roles and functions of cholesterol
A
- Maintains membrane stability/fluidity
- high temp - prevents fluidity
- low temp - prevents rigity
4
Q
roles and functions of glycoproteins and glycolipids
A
- Antigens on cell surfaces
- for cell signalling
5
Q
What is facilitated diffusion?
A
- passive movement of particles across a cell membrane
- via a channel protein or carrier protein
6
Q
how does surface area affect rate of diffusion?
A
- bigger SA = faster diffusion
- more space for particles to diffuse across/through
6
Q
role of membrane bound receptors
A
- cell signalling (hormones,neurotransmitters or drugs)
6
Q
how does temp affect membrane permeability
A
- Low temp → Less permeable (rigid).
- High temp → More permeable (fluid, proteins denature).
6
Q
how do solvents affect permeability
A
- ethanol dissolves membranes - increases permeability
7
Q
what are the 3 passive transport methods?
A
diffusion
facilitated diffusion
osmosis
8
Q
what are 3 active methods of transport?
A
active transport
endo/exocytosis
9
Q
osmosis definition
A
net movement of water molecules across a partially permeable membrane down a water potential gradient
10
Q
hypotonic sol.
A
- more water outside than inside
- higher water potential outside than inside
- net movement of water INTO cell
- animal cells - swell and burst
- plant cells - turgid
11
Q
isotonic
A
- same water potential in and outside
- no net movement of water
- animal cells - normal
- plant cells - flaccid
12
Q
hypertonic sol.
A
- less water outside than inside
- low water potential outside than inside
- net movement of water OUT of cell
- animal cells - shrink (crenation)
- plant cells - plasmolysed
