the roles of ATP in living cells Flashcards
what is metabolism?
integrated set of enzymatic reactions comprising both anabolic and catabolic reactions
what is anabolism?
synthesis of complex molecules from simpler ones (necessary energy usually derived from ATP.) Pathways end in genesis
what is catabolism?
breakdown of energy rich molecules to simpler ones (CO2, H2O, NH3). Pathways end in lysis
what happens to energy when it is released from certain reactions?
energy released is captured as adenosine triphosphate (ATP) and stored for later use in anabolic reactions
what is energy required for? 4
what about timing?
- Motion
- Transport
- Biosynthesis of essential metabolites
- Thermoregulation
- Timing of these processes does not necessarily coincide with feeding times so storage forms of food are required.
what type of systems are cells?
what does this mean? 2
- Cells are isothermal systems *maintain constant temperature)
- Heat flow cannot be used as a source of energy (heat can only do work when it passes to an area at a lower temperature)
- Free energy (energy available to perform work) is acquired from nutrient molecules
what is Gibbs free energy (g)? 5
- Energy capable of doing work at a constant temperature and pressure
- Enthalpy (H)= the heat content of the reacting system
- Entropy (S)= the randomness or disorder of a system
- change in Gibbs free energy= change in enthalpy - (temperature x change in entropy)
- the maximum energy that can be obtained from a reaction at a constant temperature and pressure
what does change in enthalpy reflect? 2
the kinds and numbers of chemical bonds that are broken and formed
Positive when energy is absorbed by the reaction
what does change in entropy reflect? 2
the formation of large complex molecules from smaller molecules or vice versa
It is positive when randomness increases (breaking up a big molecule into smaller molecules)
for the reaction A-> B
- What if there is a greater concentration of B than A at equilibrium? 3
- what if there is a greater concentration of A than B at equilibrium? 3
spontaneous or exergonic reaction
- Free energy is defined as negative
- Energy is liberated by the reaction
- Unfavourable or endergonic reaction
- Free energy is defined as positive
- Energy input is required to start the reaction
describe exergonic reactions? 3
- Products have less free energy than reactants and are more stable than the reactants. Formation of product is downhill (spontaneous)
- CATABOLISM= exergonic reactions
- Change in Gibbs free energy will be negative
describe endergonic reactions? 3
- Products have more free energy than the reactants and are less stable. Formation of products is uphill
- ANABOLISM- endergonic reactions
- Change in Gibbs free energy is positive
describe coupling of reactions?
An endergonic reaction can be driven in the forward direction by coupling it to an exergonic reaction through a common intermediate
what is ATP? 6
- adenosine triphosphate
- Provides most of the free energy required for anabolism
- ATP is the energy currency of the cell
- Achieved by phosphate group transfer
- Gibbs free energy: the energy derived from the oxidation of dietary fuels to generate ATP
- Energy is conserved at ATP and is transduced into useful work
what are ATP/ADP Mg2+ complexes? 3
- ATP in the cytosol is present as a complex with Mg2+
- Mg2+ interacts with the oxygens of the triphosphate chain making it susceptible to cleavage in the phosphoryl transfer reactions
- An Mg2+ deficiency impairs virtually all metabolism
