ATP- adenosine triphopshate

What is ATP also known as?

Universal energy currency

How can ATP make an enzyme-catalysed reaction take place?

• ATP provides a phosphate that can attach to another molecule, making it more reactive & so lowering activation energy

What does ATP consist of?

• Adenine

• Ribose sugar (Known as adenosine together with adenine)

• 3 phosphate groups

ATP structure

Describe condensation of ATP

• Rebuilds ATP by joining ADP & phosphate while releasing water

• Catalysed by enzyme ATP synthase

• ADP + Pi + (Energy) → ATP + h2o

Describe hydrolysis of ATP

• Breaks down ATP into ADP & inorganic phosphate using water, releases energy & can add phosphate groups to other substances

• ATP + h2O → ADP + Pi + (Energy)

Explain how ATP is a phosphorylated molecule

• Adenosine can be combined with one, two or three phosphorylated groups

ONE phosphate group = Adenosine monophosphate

TWO phosphate groups = Adenosine diphosphate

THREE phosphate groups = Adenosine triphosphate

Give 4 properties of ATP

• Releases energy very rapidly & immediate energy source

• Releases energy in small quantities

• Easily regenerated

• Water-soluble allowing energy-requiring processes to occur in aqueous environments

Give 2 reasons why ATP is not a good long-term energy store

• Phosphate bonds unstable so easily broken

• ATP has to be made continuously

Give 2 ways in which synthesis of ATP (condensation reaction) occur

• In chlorophyll-containing plant cells during photosynthesis

• In animal & plant cells during respiration

Why is ATP a better immediate energy source than glucose?

• Each ATP molecule releases less energy than glucose molecule, so energy is released in smaller & more manageable quantities

• Hydrolysis of ATP to ADP is single reaction that releases immediate energy whilst glucose breakdown occurs over a long series of reactions, taking longer

How does ATP store & release energy?

• Bonds between phosphate groups are unstable & have a low activation energy so easily break, releasing a considerable amount of energy

Give 4 processes ATP is involved in

• Metabolic processes - ATP provides energy needed to build up macromolecules from basic units

• Movement - ATP provides energy for muscle contraction - ATP provides energy for muscle filaments other than slide past one another & therefore shorter overall length of muscle fibre

• Secretion - ATP needed to form lysosomes necessary for secretion of cell products

• Active transport - ATP provides energy to change shape of carrier proteins in plasma membranes, which allows molecules/ ions to be moved against concentration gradient