Energy and ATP

Question 1

What is ATP made of?

Answer 1

Three phosphate groups, ribose, adenine

Question 2

What are the three instances that ATP is synthesised?

Answer 2

• In the mitochondria of plant and animal
  cells during respiration (oxidative phosphorylation)
• In the chloroplasts of chlorophyll containing plant cells during photosynthesis (photophosphorylation)
• In plant and animal cells when phosphate groups are transferred from donor molecules to ADP, requiring an enzyme (substrate-level phosphorylation)

Question 3

Properties of ATP

Answer 3

● Releases energy in small manageable amounts & rapidly
● One single bond broken - therefore, immediate energy source NOT store
● Provides energy for reactions that require it (endergonic)
● Always readily available - because when hydrolysed for energy - rapidly reformed again
● Very water soluble - therefore transportable
● However can NOT cross plasma membranes
● So remains within cells - so that it is always available to act as an energy source for activities/reactions in the cell
● Requires protein carriers to cross the membrane

Question 4

Roles of ATP

Answer 4

• Metabolic processes - anabolic reactions
• Movement - muscle contraction
• Active Transport - molecules travelling against their concentration gradient
• Secretion of products from cells
• Activation of molecules - by phosphorylation