ATP Flashcards
ENERGY
The ability to do work.
Why do organisms need energy? (6)
METABOLISM: all the reactions that take place in living organisms involve energy.
MOVEMENT: both within an organism (blood circulation) and of the organism itself (locomotion).
ACTIVE TRANSPORT: of ions and molecules against a conc. gradient across plasma membranes.
MAINTENANCE, REPAIR AND DIVISION: of cells and organelles within the cells.
PRODUCTION OF SUBSTANCES: used within organisms, e.g. enzymes and hormones.
MAINTENANCE OF BODY TEMPERATURE: in birds and mammals. These organisms are endothermic and need energy to replace heat lost to environment.
3 stages of the flow of energy through living systems.
- Light energy from Sun is converted by plants into chemical energy during photosynthesis.
- The chemical energy from photosynthesis, in the form of organic molecule, is converted into ATP during respiration in cells.
- ATP is used by cells to perform useful work.
ATP
Adenosine Triphosphate
How does ATP store energy?
The bonds between the 3 phosphate groups are unstable and so have a low activation energy, which means they are easily broken.
When they do break they release a considerable amount of energy. Usually in living cells it is only the terminal phosphate that is removed.
Equation for ATP energy release.
ATP + H2O ADP (diphosphate) + Pi(inorganic phosphate) + E (energy)
HYDROLYSIS
REVERSIBLE
PHOTOPHOSPHORYLATION
Takes (ADP + phosphate molecule= ATP) place in chlorophyll containing plant cells during photosynthesis.
OXIDATIVE PHOSPHORELATION
Occurs (ADP+ phosphate molecule=ATP) in the mitochondria of plant and animal cells during the process of electron transport.
SUBSTRATE-LEVEL PHOSPHORELATION
(ADP + Phosphate molecule=ATP) occurs in plant and animal cells when phosphate groups are transferred from donor molecules to ADP to make ATP.
What kind of energy source is ATP
immediate energy source
Why do cells not store large quantities of ATP?
It is not good at energy storage, it is an immediate energy source.
Why is ATP a better immediate energy source than glucose?
- Each ATP molecule releases less energy than each glucose molecule. The energy for reactions is therefore released in smaller, more manageable quantities rather than greater, less manageable, release of energy from a glucose molecule.
- The hydrolysis of ATP to ADP is a single reaction that releases immediate energy. The breakdown of glucose is a long series of reactions and therefore the energy release takes longer.
Why do cells which require energy for movement or active transport have lots of mitochondria?
ATP cannot be stored and so it has to be constantly made within the mitochondria .
What is ATP a source of energy for?
METABOLIC PROCESSES: Provides energy needed to build up macromolecules from basic units.
MOVEMENT: ATP provides the energy for muscle contraction.
ACTIVE TRANSPORT: ATP provides the energy to change the shape of carrier proteins in plasma membranes. Allows molecules or ions to move against the conc. gradient.
SECRETION: Needed to form the lysosomes necessary for the secretion of cell products.
ACTIVATION OF MOLECULES: When a phosphate molecule is transferred from ATP to another molecule it makes it more reactive and so lowers the activation energy of that molecule. ATP therefore allows enzyme-catalysed reactions to occur more readily.
What is ATP made from?
nucleotide base adenine combined with a ribose sugar and three phosphate groups.
