12-08: Energy & Metabolism

Metabolism

Metabolism

the sum of all chemical reactions needed to sustain life

anabolism + catabolism

Kinetic energy

motion

Potential energy

energy contained/stored in chemical bonds within a molecule

first law of thermodynamics

energy cannot be created nor destroyed - can only be converted from one form to another

anabolism

builds up

catabolism

breaks down

endergonic reactions

a need for energy

exergonic reactions

release of energy

enthalpy

a measure of energy in the system, related to the amount of hear released or absorbed by a reaction

exothermic

releases more thermal energy than it absorbs

endothermic

absorbs more thermal energy than it releases

second law of thermodynamics

in every energy conversion, some energy becomes unusable, thus increasing the entropy of the universe

entropy

a measure of randomness/disorder

positive = more disorder

negative = less disorder

Gibbs free energy

the most useful kind of energy - in a chemical change, this is the energy that is kept (not lost) and is usable

spontaneous reactions

don’t need a continual source of energy, once they hit their activation energies they will occur (e.g. once the match is lit, the fire continues)

reaction coupling

the happening of 2 reactions at the same time, aiming for a net exergonic overall reaction in order to obtain spontaneity

ATP hydrolysis

Energy for endergonic reactions in cells is mostly provided by coupling the reaction with the hydrolysis of ATP. When water reacts with it, it breaks it into ADP and the phosphate bonds to a reactant thus making it more reactive, provides energy