1.6: ATP

ATP is a __________ derivative

Nucleotide

Which nitorgenous base is always present in ATP

Adenine

Which sugar makes up ATP?

Ribose

How many phosphate groups are there in a molecule of ATP?

3

What does ATP stand for?

Adenosine triphosphate

What does ADP stand for?

Adenonsine diphosphate

What is the symbol equation for the synthesis of ATP?

ADP + P_i → ATP + H₂O

Describe the reaction that forms ATP

A condensation reaction that joins ADP and an inorganic phophate ion to form ATP and water. The reaction is catalysed by ATP synthase and is an endothermic reaction (absorbs energy)

Describe the hydrolysis of ATP

ATP is hydrolysed into ADP and an inorganic phosphate ion (water is also used). This is catalysed by the enzyme ATP hydrolase and is an exothermic reaction

Why is ATP a good energy molecule?

ATP can be hydrolysed in a single reaction which releases energy quickly.

ATP releases a small amount of energy when hydrolysed and this means less energy is wasted a heat (which could potentially case the cell to overheat)

ATP is small and can diffuse easily around the cell

ATP is polar and cannot diffuse out of the cell

Uses of ATP include…

When ATP is hydrolysed, two things happen:

• ATP hydrolysis releases energy that can be used for an energy-requiring reaction or process

• The inorganic phosphate released during hydrolysis may be used to phosphorylate another compound (stick a phosphate group onto it)

Examples of processes that require enrgy from the hydrolysis of ATP:

Anabolic/synthesis,condensation reactions (e.g. synthesiis of DNA/proteins)

Active transport (including pumping of ions and exocytosis/endocytosis)

Cell division (mitosis/meiosis)

Muscle contraction in animals

What can change the tertiary structure of a portein?

A change in the primary structure

Temperature > 37 degrees celcius

Change in pH

Binding of another molecule

Phosphorylation

Describe how phosphorylation could affect a protein (1 mark)

Phosphorylation can change the tertiary structure of a protein

Suggest how phosphorylation of an enzyme could “activate” the enzyme (cause it to become functional) (4 marks)

Phosphorylation changes the tertiary structue of the enzyme (1), thereby changing the shape of its active site (1). This means that it may become complimentary to a substrate (1), resulting in more enzyme-substrate complexes (1)