membranes🧍♂️ Flashcards
1
Q
describe structure of plasma membrane
A
- phospholipid bilayer containing proteins
- cholesterol molecules beyween phospholipids
- glycoproteins sticking out
- extrinsic and intrinsic proteins
2
Q
if cells dont take up any ammonia what can you conclude about their plasma membrane
A
-not permeable to ammonia
3
Q
where is cholesterol
A
between phospholipids
4
Q
where are glycoproteins
A
on surface
5
Q
why does freezing tissue make its enzymes react more
A
- freezing damages plasma membrane
- increases permeability of membrane to enzyme
6
Q
how do plasma membranes contribute to cell signalling
A
- release of signal molecule by exocytosis
- glycoproteins are receptors
- receptor is specific
- receptor and signal molecule are complementary
- attachment of signal molecule to receptor triggers response
7
Q
roles of membranes inside cells
A
- compartmentalisation
- isolation of metabolic pathways
- create concentration gradients
- control what enters and leaves organelles
- site for enzyme attachment
8
Q
how do proteins on surface of vesicles ensure substance gets to target organelle
A
- protein has specific shape
- receptor on organelle is complementary to protein
- receptor only found on target organelle
9
Q
what is active transport
A
- movement of substance against concentration gradient
- uses atp
- using carrier protein
10
Q
examples of active transport
A
- hydrogen ions out of companion cells
- sucrose out of sieve tube at sink
- mineral ions into root hair cell
11
Q
ethanol effect on osmosis
A
- ethanol dissolves phospholipid bilayer
- osmosis cannot occur
12
Q
suggest why low pH makes pigment leak out of beetroot cells
A
- denatures membrane proteins
- membrane permeability increased
