5.4 - Active Transport

Question 1

Define active transport.

Answer 1

Energy and carrier protein requiring process - molecules move from area of low conc to area of high conc up/against the conc gradient.

Question 2

Where is the energy required obtained from?

Answer 2

Metabolic energy supplied from ATP

- Carrier protein acts as pump

Question 3

Describe the process involved in a membrane pump.

Answer 3

1. Molecule binds to receptor
2. ATP hydrolysed, Pi binds to carrier protein changing its shape (ADP released)
3. CP shape is open so molecule can be released
4. Pi released from CP to bind with ADP to from ATP
5. CP returns to original shape

Question 4

What is bulk transport?

Answer 4

• Form of active transport
• Large molecules [enzymes, whole cells (bacterial)] are too large to move through channel/carrier proteins so bulk transport is used.
• This is where vesicles take molecules into and out of cells

Question 5

Name 2 examples of bulk transport.

Answer 5

Endocytosis

Exocytosis

Question 6

What is endocytosis?

Answer 6

Bulk transport INTO cells
PHAGOCYTOSIS - solids
PINOCYTOSIS - liquids
1) Cell surface membranes invaginates when material comes into contact
2) Membrane enfolds until it fuses forming a vesicle
3) Vesicles pinch off and moves to cytoplasm (e.g. bacterial vesicle moves to lysosome to be destroyed)

Question 7

What is exocytosis?

Answer 7

Reverse endocytosis

- Vesicles from golgi apparatus fuse with membrane and the contents are released.

Question 8

What is ATP required for?

Answer 8

• Vesicle movement across cytoskeleton
• Cell shape changing for material engulfing
• Cell membrane fusion