2: Cellular Metabolism Flashcards
laws of thermodynamics: energy can neither be created nor destroyed; it can only be transformed from one form to another
first law
law of thermodynamics: a closed system moves towards increased disorder (entropy)
second law
- energy in a system available for doing work
- energy in chemical bonds minus unusable energy
free energy
- releases free energy
- spontaneous and slow
- system loses free energy (“downhill”)
exergonic reactions
- need free energy to be added to the system
- “uphill”
- products have more energy than reactants
- powered by ATP in organisms
endergonic reactions
energy needed to break chemical bonds and form reaction products
activation energy
chemical substances that accelerate reaction rates w/o being changed by the reaction, w/o affecting the products
catalysts
biological catalysts
- reduce required AE for a reaction
- dont supply activation energy
- lowers AE barrier
enzymes
small, non-protein groups that some enzymes require to function
cofactors
provides AE needed for translation
rRNA
formed when substrate bonds w an enzyme
enzyme-substrate complex
final product of a metabolic pathway inhibits the first enzyme in said pathway
feedback inhibition
- “energy currency” of all organisms
- drives coupled reactions by serving an energy shuttle
- energy-coupling agent
ATP
component of ATP: composed of adenine and a ribose sugar
adenosine
component of ATP: consists of 3 phosphate groups connected by high energy phosphoanhydride bonds
triphosphate group
transfer of electrons from an electron donor to an electron acceptor
oxidation-reduction (redox) reactions
- last molecule to be reduced in this chain
- final acceptor determines efficiency of cellular metabolism
final electron acceptor
heterotrophs that use molecular oxygen as the final electron acceptor
aerobes
heterotrophs that use a different molecule as the final electron acceptor
anaerobes
aerobic metabolism
- oxidation of fuel molecules to recover energy
- oxygen is the final acceptor
cellular respiration
