B2.1 Membranes and Membrane Transport

Question 1

What can pass the lipid bilayer passively?

Answer 1

Small non-polar molecules

Question 2

Simple diffusion

Answer 2

Movement of substances passively across a membrane from high to low concentration

Question 3

Channel proteins

Answer 3

Transmembrane proteins facilitating the PASSIVE transport of POLAR molecules

Question 4

Aquaporins

Answer 4

Transmembrane (channel) protein facilitating the passive transport of water bidirectionally (in & out of the cell)

Question 5

Carrier proteins

Answer 5

Transmembrane proteins which must undergo a conformational change to ACTIVEly transport POLAR molecules

Question 6

Protein pumps

Answer 6

Carrier proteins

Question 7

Role of cholesterol in membrane fluidity

Answer 7

• High temps: stabilizes membrane
• Low temps: maintains membrane fluidity by preventing tight spaces

Question 8

Role of fatty acids in membrane fluidity

Answer 8

• Low melting points maintain fluidity
• Kinks create gaps which prevents freezing

Question 9

Exocytosis

Answer 9

Secretion of matter out of cells via vesicles

Question 10

Endocytosis (pinocytosis, phagocytosis)

Answer 10

Ingestion of matter via vesicles engulfing external substances and brining them inside cells