5.4 Active transport

Question 1

Define active transport

Answer 1

Movement of particles from a low concentration to a high concentration against a concentration gradient

Question 2

What are the 6 steps of active transport?

Answer 2

1. Molecule binds to receptors on carrier protein, outside of cell
2. Inside of cell, ATP binds to carrier protein and is hydrolysed into ATP and a phosphate
3. Binding of phosphate to carrier protein changes protein’s shape - this opens inside of cell
4. Molecule is released into cell
5. Phosphate is released and recombines w/ ADP to form ATP
6. Carrier protein returns to original shape

Question 3

Define bulk transport

Answer 3

Form of active transport where large molecules move in/out of cell by endo/exocytosis

Question 4

Where does material move in endocytosis?

Answer 4

INTO cells

Question 5

What are the 2 types of endocytosis? What are they for?

Answer 5

Phagocytosis - solids
Pinocytosis - liquids
* Process is same for both

Question 6

How does endocytosis work? 3 steps

Answer 6

1. Plasma membrane invaginates (bends inwards) when contact w/ material to transport
2. Membrane enfolds the material until it fuses, forming vesicle
3. Vesicle pinches off + moves to cytoplasm for further processing

Question 7

What happens during exocytosis? 2 steps

Answer 7

1. Vesicles move to + fuse with plasma membrane

2. Contents of vesicles are released OUTSIDE of cell