2.3 Energy and ATP

Question 1

What are the three parts of ATp

Answer 1

1. Adenine - a nitrogen containing organic base
2. Ribose - A sugar molecule with a 5-carbon ring structure that acts as the backbone to which the other parts are attached
3. Phosphates - a chain of three phosphate groups

Question 2

What do the bonds between phosphate groups have

Answer 2

A low activation energy

Question 3

What happens when the bond between phosphate groups are broken

Answer 3

A large amount of energy is released

Question 4

What phosphate is removed

Answer 4

usually the terminal phosphate

Question 5

What is the reaction for ATP hydrolysis

Answer 5

ATP + (H2O) –> ADP + Pi + E

Question 6

Why is the reaction a hydrolysis reaction

Answer 6

Because waster is used to convert ATP to ADP, the reaction is catalysed by ATP hydrolase

Question 7

What type of reaction is ATP conversion

Answer 7

A reversible reaction

Question 8

What catalyses the synthesis of ATP from ADP

Answer 8

ATP synthase

Question 9

Why is the reaction a condensation reaction

Answer 9

Because water is removed

Question 10

The synthesis of ATP from ADP involves the addition of a phosphate molecule to ATP. It occurs in three ways, what are they

Answer 10

1. In chlorophyll-containing plant cells during photosynthesis
2. In plant and animal cells during respiration
3. In plant and animal cells when phosphate groups are transferred from donor molecules to ADP

Question 11

Why is ATP not a good long-term energy store

Answer 11

Because of its instability. It is therefore an immediate energy store

Question 12

Why is it not a problem that cells only maintain a few seconds supply of ATP

Answer 12

because it is rapidly re-formed from ADP and inorganic phosphate and so a little goes a long way

Question 13

Why is ATP a better immediate energy source than glucose

Answer 13

1. Each ATP molecule releases less energy than each glucose molecule. The energy released for reactions is therefore released in smaller, more manageable quantities compared to glucose
2. The hydrolysis of ATP to ADP is a single reaction that releases immediate energy. Unlike glucose which is a chain of long processes

Question 14

What processes in cells is ATP used in

Answer 14

1. Metabolic processes - ATP provides the energy needed to build up macromolecules from their basic units. e.g. starch from glucose, proteins from amino acids
2. Movement - ATP provides the energy for muscle contraction
3. Active transport - ATP provides the energy to change the shape of carrier proteins in the plasma membrane
4. Secretion - ATP is needed to form the lysosomes necessary for the secretion of cell products
5. Activation of molecules - The inorganic phosphate released during ATP hydrolysis of ATP can be used to phosphorylate other compounds to make them more reactive, thus lowering the activation energy in enzyme-catalysed reactions. e.g. the addition of phosphate to glucose during glycolysis.