3.1.6 ATP

Question 1

what are the three energy processes that require ATP?

Answer 1

1. metabolic processes = ATP provides the energy needed to build up macromolecules from their basic unts eg making starch from glucose
2. movement = ATP provides the energy for the filaments of muscle to slide past one another and therefore shorten the overall muscle fibre
3. active transport = ATP provides the energy to change the shape of carrier proteins in plasma membranes, allows molecules to be be moved against a concentration gradient

Question 2

ATP as a immediate energy source

Answer 2

better than glucose

1. each ATP molecule releases less energy than each glucose molecule
   ENERGY FOR REACTIONS IS THEREFORE RELEASED IN SMALLER, MORE MANAGEABLE QUANTITIES RATHER THAN GLUCOSE MOLECULE
2. hydrolysis of ATP to ADP is a single reaction that releases immediate energy
   BREAKDOWN OF GLUCOSE IS A LONG SERIES OF REACTIONS = TAKES LONGER

Question 3

roles of ATP

Answer 3

ATP = immediate energy source of a cell

cells can only maintain a few seconds supply
NOT A PROBLEM AS ATP IS RAPIDLY REFORMED FROM ADP AND INORGANIC PHOSPHATE

ATP cannot be stored and so has to be continuosly made in the mitochondria

Question 4

synthesis of ADP

Answer 4

conversion of ATP to ADP is a reversible reaction and therefore energy can be used to add an inorganic phosphate to ADP to re-form ATP

condensation reaction = water is removed

synthesis of ATP to ADP invoves the addition of a phosphate molecule to ADP:
1. in chlorophyll = containing plants cells during photosynthesis (photophosphorylation)
2. in plant and animal cells during respiration (oxidation phosphorylation)
3. in plant and animal cells when phosphate groups are transferred from doner molecules to ADP (substrate-level phosphorylation)

Question 5

how does ATP store energy

Answer 5

ATP = adenosine triphosphate

ATP is a nucleotide and three phosphate groups store ATP

bonds between these phosphate groups are unstable and have a low activation energy so easily broken

when they do break they release a considerable amount of energy

water is used to convert ATP to ADP (hydrolysis reaction)
REACTION IS CATALYSED BY ENZYME ATP HYDROLASE

Question 6

what is the structure of ATP?

Answer 6

ATP is a phosphorylated macromolecule

3 parts:

1. adenine: nitrogen - contaning organic base
2. ribose: a sugar molecule with a 5-carbon ring structure (pentose sugar) that acts as the backbone to which the other parts are attached
3. phosphates: a chain of three phosphate group