Energy and ATP Flashcards
What are the three parts of the phosphorylated macromolecule, ATP?
adenine - a nitrogen containing organic base.
ribose - a sugar molecule with a 5-carbon ring structure acts as the backbone to which other parts attach.
phosphates - a chain of three phosphate groups
How does ATP store energy?
Bonds between phosphate groups are unsaturated and so have low activation energy, meaning they are easily broken. When they break they release a large amount of energy.
How is ADP formed from ATP?
It is a reversible reaction where energy is used to add Pi to ADP to re-form ATP. The reaction is catalysed by the enzyme ATP synthase.
Is ATP synthesis a condensation or hydrolysis reaction?
As water is removed in this reaction, it is known as a condensation reaction.
Where does photophosphorylation occur?
In chlorophyll-containing plant cells during photosynthesis.
Where does oxidative phosphorylation occur?
In plant and animal cells during respiration.
Where does substrate-level phosphorylation occur?
In plant and animal cells when phosphate groups are transferred from donor molecules to ADP.
What makes ATP an immediate energy source of a cell?
The instability of its phosphate bonds, meaning it is not a good long-term energy store.
Why is ATP a better immediate energy source than glucose?
- The energy released from ATP molecules is much smaller and therefore more manageable quantity than glucose which produces a less manageable release of energy.
- Hydrolysis of ATP to ADP is a single reaction releasing immediate energy, whereas the breakdown of glucose is a series of reactions, therefore energy release takes longer.
Why does ATP need to be continuously made within the mitochondria?
ATP cannot be stored. Cells such as muscle fibres and the epithelium of the small intestine require energy for movement, so possess large numbers of mitochondria.
What is the role of ATP in metabolic processes?
ATP provides energy required to build up macromolecules, such as making starch from glucose.
What is the role of ATP in movement?
ATP provides energy for muscle contraction.
What is the role of ATP in active transport?
ATP provides energy to change the shape of carrier proteins in plasma membranes, allowing molecules or ions to be moved against a concentration gradient.
What is the role of ATP in secretion?
ATP is needed to form the lysosomes necessary for secretion of cell products.
What is the role of ATP in the activation of molecules?
Pi can be used to phosphorylate other compounds in order to male them more reactive, thus lowering activation energy in enzyme-catalysed reactions.
