Energy and ATP

Question 1

What does ATP stand for?

Answer 1

Adenosine triphosphate

Question 2

What kind of molecule is an ATP molecule?

Answer 2

A phosphorylated macromolecule

Question 3

What are the 3 parts of an ATP molecule?

Answer 3

Adenine - a nitrogen containing organic base
Ribose - a sugar molecule with a 5 carbon ring(pentose sugar) that acts as the backbone to which the other parts are attached
Phosphates - a chain of 3 phosphate groups

Question 4

What is just adenine and ribose known as?

Answer 4

Adenosine

Question 5

What is just adenine, ribose and 1 phosphate group known as?

Answer 5

Adenosine monophospahte (AMP)
If it has 2 phosphate groups, it is known as Adenosine diphosphate (ADP)

Question 6

How does ATP store energy?

Answer 6

• It is a nucleotide and has 3 phosphate groups
• The bonds between these groups are unstable and have a low activation energy, so they are easily broken

Question 7

What happens when the bonds between the phosphate groups in an ATP break?

Answer 7

They release a considerable amount of energy

Question 8

What usually happens in living cells in the hydrolysis of an ATP molecule?

Answer 8

Only the terminal phosphate is removed

Question 9

What is the hydrolysis equation of ATP?

Answer 9

ATP + H2O = ADP + P(inorganic phospate) + E

Question 10

What is the hydrolysis reaction of ATP catalysed by?

Answer 10

The enzyme ATP hydrolyse (ATPase)

Question 11

What kind of reaction is the conversion of ATP to ADP and hence, what does this mean?

Answer 11

Reversible so energy can be used to add an inorganic phosphate to ADP to re-form ATP (synthesis of ATP)

Question 12

What is the synthesis of ATP catalysed by?

Answer 12

The enzyme ATP synthase

Question 13

What kind of reaction is the synthesis of ATP?

Answer 13

As water is removed, the reaction is known as a condensation reaction

Question 14

In what 3 ways does the synthesis of ATP from ADP occur?

Answer 14

In chlorophyll
In plant and animal cells (this is in 2 different ways)

Question 15

How does the synthesis of ATP occur in chlorophyll?

Answer 15

In chlorophyll containing plant cells during photosynthesis (photophosphorylation)

Question 16

How does the synthesis of ATP occur in plant and animal cells?

Answer 16

• During respiration (oxidative phosphorylation)
• When phosphate groups are transferred from donor molecules to ADP (substrate level phosphorylation)

Question 17

What is the role of ATP?

Answer 17

It is the immediate energy source of a cell (not long term due to instability of phosphate bonds)

Question 18

In what quantities do cells store ATP?

Answer 18

• In small quantities, just a few seconds supply
• This is not a problem as ATP is regularly re-formed from ADP and inorganic phosphate (Pi)

Question 19

Why is ATP a better immediate energy source than glucose?

Answer 19

• Each ATP molecule releases less energy than each glucose molecule so the energy for reactions is released in smaller, more manageable quantities
• The hydrolysis of ATP to ADP is a single reaction that releases immediate energy. The breakdown of glucose is a long series of reactions and so the release of energy is longer

Question 20

Why do cells that require a lot of energy have many large mitochondria?

Answer 20

ATP cannot be stored and so has to be continuously made in the mitochondria of cells that need it

Question 21

Which processes is ATP used in?

Answer 21

Metabolic processes
Movement
Active transport
Secretion
Activation of Molecules

Question 22

How is ATP used in metabolic processes?

Answer 22

Provides the energy needed to build up macromolecules from their basic units e.g. starch from glucose

Question 23

How is ATP used in movement?

Answer 23

Provides energy for muscle contraction. Provides energy for the filaments of muscle to slide past one another and shorten the overall length of a muscle fibre

Question 24

How is ATP used for active transport?

Answer 24

Provides energy to change shape of carrier proteins in plasma membranes. Allows molecules or ions to be moved against a concentration gradient

Question 25

How is ATP used for secretion?

Answer 25

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

Question 26

How is ATP used for the activation of molecules?

Answer 26

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