Biological Molecules: the nucleotide ATP

Question 1

What is ATP used for in cells?

Answer 1

As the main energy source to carry out processes within cells

Question 2

What are the 3 components of ATP?

Answer 2

3 phosphate groups, a ribose sugar and an adenine base

Question 3

What does ATP stand for?

Answer 3

Adenosine triphosphate

Question 4

How are the phosphate groups easily broken?

Answer 4

Because the bonds between the phosphate groups are unstable so have a low activation energy making them easy to break

Question 5

How is energy stored in the ATP released?

Answer 5

The hydrolysis of the terminal phosphate (the 3rd one) as the bond is broken

Question 6

Give the equation that shows ATP transferring energy

Answer 6

ATP + H20 -> ADP + Pi + E

E being energy

Question 7

What catalyses the hydrolysis of ATP?

Answer 7

The enzyme ATP hydrolase

Question 8

What reaction does ATP synthase catalyse?

Answer 8

The condensation of ADP and Pi to form ATP

Question 9

Describe the ATP cycle

Answer 9

going from ATP to ADP, a molecule of water is required and an inorganic phosphate (Pi), and energy is released making it an exergonic process. Then going from ADP to ATP, a Pi and energy is required with a molecule of water being released making it an endergonic process.

Question 10

What are the three ways synthesis of ATP to ADP occurs?

Answer 10

• Using light energy in photosynthesis (photophosphorylation)
• in plant and animal cells using glucose and other fuels in respiration (oxidative phosphorylation)
• using high energy phosphate substances in plant and animal cells when phosphate groups are transferred from donor cells to ADP (substrate-level phosphorylation )

Question 11

For the formation of ATP from ADP and Pi, what kind of energy process is it and what kind of energy process are the reactions that fuel it?

Answer 11

The formation of ATP from ADP and Pi is an endergonic process that is fuelled by exergonic reactions

Question 12

For the hydrolysis of ATP to ADP and Pi, what kind of energy process is it and what kind of energy process are the reactions that fuel it?

Answer 12

the hydrolysis of ATP to ADP and Pi is an exergonic process fuelled by endergonic reactions

Question 13

What does exergonic and endergonic mean?

Answer 13

Exergonic releases energy and endergonic absorbs energy

Question 14

Give two reasons ATP is a better immediate energy source than glucose

Answer 14

• Because each ATP molecule releases less energy than each glucose molecule, the energy for the reactions is released in much smaller and more manageable quantities than the energy released by a glucose molecule
• the hydrolysis of ATP to ADP is a single reaction that releases immediate energy whereas the breakdown of glucose is a long series of reactions and therefore the energy release takes longer

Question 15

Why is ATP used in metabolic processes?

Answer 15

As it provides the energy needed to build up macromolecules from their basic units e.g. making starch from glucose or polypeptides from amino acids

Question 16

How is ATP used in movement?

Answer 16

As in muscle contraction, ATP provides the energy for the filaments of muscle to slide past each other and therefor shorten the overall length of a muscle fibre

Question 17

How is ATP used in active transport?

Answer 17

By providing energy to change the shape of carrier proteins in plasma membranes allowing molecules or ions to move against the concentration gradient

Question 18

Why is ATP used in secretion?

Answer 18

As it’s needed to form the lysosomes need for secretion of cell products

Question 19

How is ATP used in activation of molecules?

Answer 19

As the inorganic phosphate released during the hydrolysis of ATP can be used to phosphorylate other compounds in order to make them more reactive thus, lowering the activation energy in enzyme catalysed reactions e.g. the addition of phosphate to glucose molecules at the start of glycolysis

Question 20

What energy requiring processes is ATP used for?

Answer 20

• metabolic processes
• movement
• active transport
• secretion
• activation of molecules