Movement across Membranes

Question 1

Function of membranes? (2)

Answer 1

1) Maintain the internal environment

2) Transport (Selectively permeable)

Question 2

What are the three driving forces for substances moving in and out of cells?

Answer 2

1) Chemical (Force D Proportional to CG)
2) Electrical (F depends on MP and ion charge)
3) Electrochemical (Net direction equal to sum of C&E forces)

Question 3

Three types of Carrier proteins?

Answer 3

1) Uniport
2) Symport
3) Antiport (Opposite directions)

Question 4

What are channel proteins selective on? (2)

Answer 4

Size and Charge of Molecule?

Question 5

What is the difference between primary and secondary active transport?

Answer 5

1) Primary: Directly uses a source of energy

2) Secondary: Transport of substance coupled to transport of an ion, moving down a gradient

Question 6

Two types of Cell signalling?

Answer 6

1) Intracellular: Steroid

2) Cell-Surface: Peptide hormones

Question 7

Three examples of endocytosis?

Answer 7

1) Phagocytosis
2) Pinocytosis (Small drops of E-C Fluid)
3) Receptor Mediated (Proteins on surface capture a specific molecule)