Cell Membranes

Question 1

Function of glycoproteins?

Answer 1

Act as receptors when cell signalling
Act as antigens
Attach to water molecules to stabilise membrane
Recognition of self and non-self cells

Question 2

What happens when plant cell is placed in pure water?

Answer 2

Water moves in by osmosis
Cell wall prevents bursting
Membrane pushes against wall
Plant cell is turgid

Question 3

What happens when an animal cell is placed in pure water?

Answer 3

Water moves in by osmosis
Animal cell bursts open - no cell wall
It is cytolysed

Question 4

What happens when an animal cell is placed in a concentrated sugar solution?

Answer 4

Water moves out of cell by osmosis
Animal cell shrinks and appears wrinkled
It is crenated

Question 5

What happens when a plant cell is placed in a sugar solution?

Answer 5

Water moves out of plant cell
Plant cell membrane pulls away from cell wall as water leaves
The cell is plasmolysed

Question 6

What is pinocytosis?

Answer 6

Cells ingesting liquids by Endocytosis

Question 7

Endocytosis description

Answer 7

A segment of the plasma membrane surrounds and encloses the molecule to bring in the cell enclosed in a vesicle

Question 8

Roles of membranes within cells?

Answer 8

Mitochondria- cristae provide large SA for aerobic respiration
Chloroplasts- thylakoids- photosynthesis occurs
Epithelial cells- contain digestive enzymes to break down sugars

Question 9

When temperature drops?

Answer 9

fatty acids becomes compressed
Unsaturated fatty acids kinks maintain fluidity
Cholesterol prevents phospholipids from packing too closely

Question 10

When temperature increases?

Answer 10

Phospholipids have more kinetic energy
Permeability and fluidity increases
May affect infolding during endocytosis