3.1.6 ATP Flashcards
What does ATP stand for
Adenosine triphosphate
Describe the structure of ATP
- Adenine
- base
- triphosphate
Describe the bonds between the phosphate groups
- Often called “high energy bonds”, yet they have a low activation energy, and so they’re unstable. This means that they are easily hydrolysed
Describe what happens when one of these “high energy bonds” are hydrolysed
- Energy is released, which can be used to power metabolic reactions
What are the 2 main roles of ATP in cells
- Release of energy to power metabolic reactions
- Phosphorylation of other molecules
Describe the process of phosphorylation (shape)
- The addition of a phosphate ion can change the shape of a molecule
- e.g. during active transport, a protein in the membrane changes shape to transport molecules across
Describe the process of phosphorylation (activation energy)
- The addition of a phosphate ion can lower the activation energy of other molecules, making them more reactive
- e.g during glycolysis (the first stage of respiration), glucose is phosphorylated to make it more reactive
Describe the hydrolysis reaction of ATP
ATP + H2O –> ADP + Pi (+ Energy)
- This reaction is catalysed by the enzyme ATP hydrolase
Describe the condensation reaction of ADP (resynthesised)
ADP + Pi –> ATP + H2O
- This reaction is catalysed by the enzyme ATP synthase during photosynthesis, or during respiration.
Explain why ATP is better intermediate energy source than glucose
- Each ATP releases less energy compared to glucose therefore this is more manageable for the cells.
- Additionally, the hydrolysis of ATP to ADP is a single step reaction, unlike the breakdown of glucose which is several steps and would take longer.
Describe what is meant by photophosphorylation
ATP is synthesised during photosynthesis
Describe what is meant by oxidative phosphorylation
ATP is synthesised during respiration
Describe what is meant by substrate-level phosphorylation
ATP is synthesised by the direct transfer of phosphate group to a molecule of ADP
Describe why ATP cannot be stored in cells
Due to unstable bonds between phosphate groups
Explain the advantages of ATP, in comparison to glucose.
- Each ATP molecule releases less energy than glucose, therefore, this is more manageable for the cells and more efficient
- The hydrolysis of ATP to ADP is a single reaction, therefore energy is released quickly, unlike glucose, which requires a long series of reactions to be broken down
- ATP can be easily reformed from ADP and Pi, therefore there is always a ready supply of ATP within cells, even though it cannot be stored