5.4 Active Transport

Question 1

What is active transport?

Answer 1

movement of particles

across a plasma membrane

against a concentration gradient

requiring metabolic energy

Question 2

Outline the steps of active transport across a plasma membrane using a carrier protein:

Answer 2

1. Molecule binds to specific complementary receptor on carrier protein
2. On inside of cell, ATP binds to carrier protein, hydrolysed ⟶ ADP + P_i
3. Phosphate binds to carrier protein, causes conformational change.
4. Molecule released into cell.
5. Phosphate released from carrier protein, phosphorylates ADP & causes carrier protein to return to original shape.

Question 3

What is bulk transport?

Answer 3

Form of active transport

where large molecules or whole bacterial cells

are moved in/out of cells by exocytosis/endocytosis

Question 4

What are the 2 main types of bulk transport?

Answer 4

1. ENDOCYTOSIS - bulk transport of material into cell by invagination of plasma membrane, forming vesicle
   
   1. Phagocytosis (solids), pinocytosis (liquids)
2. EXOCYTOSIS - bulk transport of material out of cell by fusion of vesicles with plasma membrane & release of contents

Question 5

What is endocytosis?

Answer 5

Bulk transport

of materials into cell

by invagination of plasma membrane

& formation of a vesicle

Question 6

What is exocytosis?

Answer 6

Bulk transport of materials

out of cell

by vesicle fusing with plasma membrane

releasing contents

Question 7

What are the 2 different types of endocytosis & how are they different?

Answer 7

PHAGOCYTOSIS - endocytosis of solid material

PINOCYTOSIS - endocytosis of liquid material

Question 8

The vesicles which fuse with the plasma membrane in exocytosis are usually formed by the ____.

Answer 8

golgi apparatus

Question 9

What causes the conformational change in shape of carrier proteins during active transport?

Answer 9

Binding of phosphate to carrier protein

after ATP binds to carrier protein & is hydrolysed