ATP?
- Adenosine Tri Phosphate
- an immediate source of energy for biological processes - reactions must hv constant, steady supply
- nucleotide derivative
Structure of ATP?
contains: Adenine (nitrogenous base), ribose (pentose sugar) & 3 inorganic phosphate groups (Pi) (inorganic as no carbon)
How ATP is created?
- made during respiration from ADP (adenosine diphosphate) - by addition of inorganic phosphate - via condensation reaction & using enzyme: ATP synthase
- small amount of energy needed
How ATP is an immediate source of energy?
ATP hydrolysed into ADP + Pi using enzyme: ATP hydrolase
- ATP + water -> ADP + Pi + energy
- by breaking 1 of bonds between Pi groups in hydrolysis reaction - small amount of energy released to surrounding - used in chemical reactions
- immediate energy source cos: only 1 bond has to be hydrolysed to release energy
Phosphorylation?
ATP can transfer energy to diff compounds
- Pi released during hydrolysis of ATP can be bonded onto diff compounds to make them more reactive aka phosphorylation
- happens to glucose at start of respiration to make more reactive
3 ways the synthesis of ATP by +Pi to ADP can occur?
- In mitochondria of plant & animal cells during respiration aka ‘oxidative phosphorylation’
- In thylakoid membranes of chloroplasts of plant cells during photosynthesis aka ‘photophosphorylation’
- In plant & animal cells - when phosphate groups are transferred from donor molecules to ADP, requiring an enzyme aka ‘substrate-level photophosphorylation’
Properties of ATP?
(diff w glucose - immediate source)
1. releases energy in small, manageable amounts & rapidly so - no energy wasted (cells don’t overheat from wasted heat energy & r less likely to run out of resources)
2. a small & soluble to easily transport around cell
3. only 1 bond hydrolysed to release energy - y immediate source NOT store
4. it can transfer energy to another molecule by transferring 1 of its Pi
5. can’t pass out of cell (plasma membranes/protein carriers) & is rapidly reformed again so - cell alw has immediate supply of energy (ATP or ADP + Pi)
Roles of ATP?
- metabolic processes - anabolic reactions
- movement - muscle contraction
- active transport - molecules travelling against conc. gradient
- secretion of products from cells
- activation of molecules - phosphorylation
