3.1.6 - ATP

Question 1

describe how an ATP molecule is formed from its component molecules (4)

Answer 1

1. adenine, ribose sugar and three phosphates
2. joined together by a condensation reaction
3. joined together by enzyme ATP synthase

Question 2

water is used to hydrolyse ATP.
name the two products of ATP hydrolysis (1)

Answer 2

1. adenosine diphosphate (ADP)
2. inorganic phosphate (Pi)

Question 3

scientists investigated the use of a new antibiotic to treat bladder infection. this antibiotic inhibits the bacterial ATP synthase enzyme.

the new antibiotic is safe to use in humans because it does not inhibit the ATP synthase found in human cells.

suggest why human ATP synthase is not inhibited and bacterial synthase is inhibited (1)

Answer 3

any one:

1. human ATP synthase has a different tertiary structure to bacterial ATP synthase
2. human ATP synthase has a different shape active site to bacterial ATP synthase
3. antibiotic is not complementary to human ATP synthase

Question 4

ATP is an energy source used in many cell processes.

give two ways in which ATP is a suitable energy source for cells to use (2)

Answer 4

1. releases relatively small amount of energy/little energy lost as heat (there is little danger of thermal death of cells)
2. releases energy instantaneously (energy is readily available)
3. phosphorylates other compounds, making them more reactive
4. can be rapidly re-synthesised
5. does not leave cells

Question 5

describe how ATP is resynthesised in cells (2)

Answer 5

1. from ADP and phosphate
2. by ATP synthase
3. during respiration/photosynthesis

Question 6

give two ways in which the hydrolysis of ATP is used in cells (2)

Answer 6

1. to provide energy for other reactions
2. to add phosphate to other substances and make them more reactive/change their shape

Question 7

write a simple equation to show how ATP is synthesised from ADP (1)

Answer 7

ADP + Pi —> ATP

Question 8

give two ways in which the properties of ATP make it a suitable source of energy in biological processes (2)

Answer 8

1. energy released in small amounts
2. soluble
3. involves a single/simple reaction

Question 9

humans synthesise more than their body mass of ATP each day. explain why it is necessary for them to synthesise such a large amount of ATP (2)

Answer 9

1. ATP cannot be stored, it is an immediate source of energy
2. ATP only releases a small amount of energy at a time

Question 10

describe the role of DNA polymerase in DNA replication (1)

Answer 10

joins nucleotide together to form a new strand (by forming phosphodiester bonds)

Question 11

other than being smaller, give two ways in which prokaryotic DNA is different from eukaryotic DNA (2)

Answer 11

1. prokaryotic DNA is circular
2. prokaryotic DNA is not associated with histones#
3. prokaryotic DNA does not contain any introns