3.1.6 ATP

Question 1

Where in the cell is ATP synthesised?

Answer 1

Mitochondria

Question 2

When is ATP synthesised?

Answer 2

1) Photophosphorylation - during photosynthesis – in chlorophyll containing plant cells
2) Oxidative phosphorylation - during respiration - in plant and animal cells
3) Substrate-level phosphorylation - when phosphate groups are transferred from donor molecules to ADP - in plant and animal cells

Question 3

Why is ATP a good immediate energy source?

Answer 3

1) Unstable bonds between phosphate groups (especially phosphates 2 and 3) = they break easily = provides an immediate and short term supply of energy
2) It can’t be stored for longer than a few seconds
3) It releases energy in small amounts

4) It releases energy rapidly and in one step,
- transfers energy directly to the reaction requiring it

Question 4

Why ATP > glucose

Answer 4

1. ATP hydrolysis is a quick, one-step reaction - glucose breakdown is a long, multi stage process
2. Each ATP molecule stores only a small amount of energy - glucose would release more energy than is needed
3. ATP diffuses easily within cells but cell membranes are impermeable to it

Question 5

What type of molecule is ATP

Answer 5

a nucleotide derivative

Question 6

What does ATP stand for

Answer 6

adenosine triphosphate

Question 7

ATP structure

Answer 7

a molecule of ribose
a molecule of adenine
three phosphate groups

Question 8

What catalyses the Hydrolysis of ATP to adenosine diphosphate (ADP) and an inorganic phosphate group (Pi)

Answer 8

the enzyme ATP hydrolase

Question 9

Hydrolysis of ATP

Answer 9

ATP (+water)→ ADP + Pi

Question 10

What is Pi

Answer 10

an inorganic phosphate group

Question 11

Role of ATP hydrolase

Answer 11

catalyses the Hydrolysis of ATP

to adenosine diphosphate (ADP) and an inorganic phosphate group (Pi)

Question 12

Uses of the hydrolysis of ATP

Answer 12

• The hydrolysis of ATP can be coupled to energy-requiring reactions within cells
• The inorganic phosphate released during the hydrolysis of ATP can be used to phosphorylate other compounds, often making them more reactive

Question 13

Give energy requiring processes in the body that ATP is used for

Answer 13

1) Movement
2) Activation of molecules
3) Metabolic processes
4) Active transport
5) Secretion

Question 14

Role of ATP in metabolic processes

examples

Answer 14

Provides energy needed to build up macromolecules from their basic units

• Glucose → starch
• Amino acids → polypeptides

Question 15

Give the 2 roles of ATP in movement

Answer 15

• Provides the energy needed for muscle contraction
• In muscle contraction, provides the energy needed for the filaments of muscle to slide past each other - and therefore shorten the overall length of muscle fibre

Question 16

Role of ATP in active transport

Answer 16

Provides the energy needed to change the shape of carrier proteins in plasma membranes

So molecules or ions can move against a concentration gradient

Question 17

Role of ATP in secretion

Answer 17

Needed to form the lysosomes - necessary for the secretion of cell products

Question 18

Role of ATP in activation of molecules

Answer 18

Inorganic phosphate released can be used to phosphorylate other compounds - to make them more reactive, - lowering their activation energy

Question 19

How is ATP resynthesized

Answer 19

by the condensation of ADP and Pi

Question 20

What catalyses ATP synthesis

Answer 20

the enzyme ATP synthase

Question 21

When does ATP synthesis occur

Answer 21

during photosynthesis
during respiration
involves the enzyme ATP synthase