5.4 Active Transport

Question 1

Active transport

Answer 1

The movement of molecules or ions into or out of a cell from a region of low concentration to a region of high concentration, against the concentration gradient
This process requires energy and carrier proteins

Question 2

Process of active transport

Answer 2

Molecule binds to receptors in the channel of the carrier protein on the outside of the cell
On the inside of the cell, ATP binds to the carrier protein and is hydrolysed into ADP and phosphate
Phosphate molecule binds to carrier protein, causing the shape to change - opens up into the inside of the cell
Molecule is released to the inside
Phosphate molecule is released from carrier proteins and recombines with ADP to form ATP
Carrier protein returns to original shape

Question 3

Endocytosis

Answer 3

Bulk transport of material into cells

2 types - phagocytosis and pinocytosis

Question 4

Phagocytosis

Answer 4

Bulk transport of solids into cells

Question 5

Pinocytosis

Answer 5

Bulk transport of liquids into cells

Question 6

Endocytosis process

Answer 6

Cell surface membrane invaginate (bend in)
Membrane enfolds material until it fuses and forms a vesicle
Vesicle pinches off and moves into cytoplasm to transfer material

Question 7

Exocytosis

Answer 7

Vesicles are usually formed by Golgi apparatus and move towards and fuse with the cell surface membrane
Contents are released outside the cell

Question 8

Why is energy required for bulk transport?

Answer 8

Movement of vesicles along cytoskeleton
Changing shape of cells to engulf materials
Fusion of cell membranes as vesicles form