2.3- Energy and ATP

Question 1

structure of ATP

Answer 1

Adeneine- nitrogen containing organism base
ribose- pentose sugar
3 phosphate groups
joined by phosphodiester bonds

Question 2

how does ATP release energy

Answer 2

phosphodiester bonds have a low activation energy so are easily hydrolysed which releases energy

Question 3

reactions of ATP

Answer 3

ATP hydrolysed to ADP and Pi by ATPase
ADP and Pi is synthesised by ATP synthase to form ATP

Question 4

3 types of phosphorylation

Answer 4

1. Photophosphorylation- in chlorophyll during photosynthesis
2. Oxidative phosphorylation- in plant and animal cells during respiration
3. Substrate level phosphorylation- in plant and animal cells when phosphate groups are transferred to ADP from donor molecules

Question 5

why is ATP a better immediate energy source than glucose

Answer 5

• energy is released in smaller, more manageable quantities
• hydrolysis of ATP is a single reaction that releases immediate energy whereas the breakdown of glucose is a long series of reactions so energy release takes longer

Question 6

uses of ATP

Answer 6

• metabolic processes: provides the energy needed to build up macromolecules from smaller ones
• movement: provides energy for sliding filament mechanism allowing the muscle to contract
• active transport: provides energy to change shape of carrier proteins allowing for molecules and ions to be moved against a concentration gradient
• secretion: needed to form lysosomes necessary for the secretion of cell products
• activation of molecules: Pi released can be used to phosphorylate other compounds in order to make them more reactive so lowering the activation energy in enzyme catalysed reactions