Structure Of Cell Membranes

Question 1

Roles of cell membranes at the surface of cells

Answer 1

Separates cells contents, regulates transport of materials in and out, contains enzymes involved in specific metabolic pathways, releases chemicals to signal other cells,

Question 2

Roles of cell membranes within cells

Answer 2

Mitochondria have folded inner membrane to increase SA, inner membrane of chloroplasts contains chlorophyll, digestive enzymes catalyse reactions

Question 3

Explain fluid mosaic model

Answer 3

Singer and Nicholson 1972

Mosaic- bilayer with proteins floating in it

Fluid - lipid molecules change places and some proteins move

Question 4

Membrane in neurones

Answer 4

Protein channels and carriers allow entry and exit of ions

Myelin sheath gives several layers of membrane

Question 5

Membrane in white blood cells

Answer 5

Special protein receptors recognise antigens of foreign cells

Question 6

Membrane in root hair cell

Answer 6

Many carrier proteins to actively transport nitrate ions

Question 7

Membranes in mitochondria

Answer 7

Folded inner membrane gives large SA

Question 8

Phospholipid bilateral contains

Answer 8

Phospholipids (hydrophilic head, phobic tail)
Cytoskeletal filaments
Cholesterol - strength and flexibility
Channel and carrier proteins
Glycolipid - carb chain attached to lipid
Glycocalyx - v hydrophilic
Glycoproteins - carb chain attached to protein