Life at the cellular level 3 Flashcards
what is the 1st law of energy?
energy can be converetd from one form to another but cannot be created or destroyed
what is the 2nd law of energy?
all transformations lead to more disorder (entropy increases)
define gibbs free energy
G = H - TS
free energy = enthalpy - (absolute temperature x entropy)
when will a spontaneous reaction occur? (3)
occurs when:
- a system gives up energy
- there is an increase in entropy
- there is a negative change in free energy (-ve delta G)
why is reaction coupling used?
biological reactions tend to be thermodynamically unfavourbale, reaction coulping allows the energy from favourbale reactions to be stored and used to drive unfavourbale reactions
why are reaction pathways used?
for life to happen reactions cannot reach equilibrium, so pathways are set up which create intermediate products which then form products which are excreted, this prevents equilibrium from being reached
what is a dynamic steady state?
a reaction in which the rate at which an intermediary product is formed and broken down is the same (allowing the concentration of the inetrmediate product to remain constant)
what is metabolism?
a chemical process in a living organism by which food is used for tissue growth or energy production
what are catabolic processes?
reactions which break down products into their constituent units (tend to be exergonic)
what are anabolic processes?
reactions in which larger molecules are formed form smaller molecules (tend to be endergonic)
what is an exergonic reaction?
a reaction in which energy is given out (spontaneous)
what is an endergonic reaction?
a reaction which needs energy in order to occur
what do molecules need to be in order to be used in reaction coulping?
a high potential energy
how is ATP used in reaction coulping?
- exergonic catabolic reactions save free energy by forming ATP
- this free energy is released by the breakdown of ATP which drives endergonic anabolic reactions
what is is PEP
phosphoendypyruvate
- an intermediary molecule in respiration that is converetd to pyruvate, releasing energy that is stored as ATP
