ATP (Adenosine triphosphate)
Highly unstable nucleotide consisting of adenine, ribose (sugar), and three tightly-packed phosphate groups. ATP is used as a source of energy in almost all organisms as its high-energy phosphate bonds (specifically between the last two phosphates) can be broken through a process called hydrolysis, releasing energy that can be harnessed by the cell.
Energy measurement
Calories (energy required to heat 1 g of water by 1 degree)
Metabolism
Totality of an organism’s chemical reactions, which slows down with age, related to sex, genetics, exercise, and nutrition.
Anabolic/endergonic reactions
Bonds formed via input, requiring energy (low to high)
Catabolic/exergonic reactions
Bonds broken, releasing energy (high to low)
Kinetic energy
Energy of motion
Chemical energy
Potential energy within bonds
Order of electronegativity
O, C, N, H
Potential energy
Energy possible due to structure/location of bonds
First law of thermodynamics
Energy within the universe is constant, nothing is created or destroyed.
Second law of thermodynamics
Transformations of energy increase entropy (and kinetic energy as a byproduct)
Entropy (S)
Measure of disorder in the universe
Life is made possible by ordered concentrations of energy
Sun provides photons, transformed via photosynthesis, etc
Spontaneous reaction
is energetically favourable, does not require energy input.
Free energy
How much energy can actually be used for work/measure of a system’s instability
∆G = ∆H - T∆S
Gibbs free energy change, related to enthalpy, temperature and entropy change. This is the energy available to do work during a chemical or physical process.
If G is negative, reaction is spontaneous and exergonic. If positive, vice versa, if 0, equilibrium.
T refers to temperature in Kelvin.
If H is negative, reaction is exothermic (releasing heat). If positive, vice versa,
If S is negative, the system becomes more ordered. If positive, vice versa.
Energy coupling
Uses energy released from catabolic reactions to drive anabolic reactions with energy in ATP. When ATP is hydrolyzed, it releases energy, which can be used for powering endergonic reactions.
Enzyme
Protein that catalyzes a chemical reaction. Initiates the reaction, speeds up its process, and ensures outcome is always the same. Often work together to form longer pathways. Catalyze reactions in mild pH, temperature, pressure.
Activation energy (EA)
Energy required to overcome energy barrier before a chemical reaction can begin
Active site
Region where substrate is bound (like a pocket or groove). When substrate enters, the substrate forms weak (hydrogen/ionic) bonds with the enzyme, inducing a change in protein shape.
Catalytic cycle
Process by which enzyme catalyzes a substrate, consisting of initiation, transition facilitation, termination.
Initiation (catalytic cycle)
Reactants come together and bind in active site.
Transition facilitation (catalytic cycle)
Binding induces a transitional state, wherein the reactant/R-group interactions lower activation energy and substrate is converted to products.
Termination
Products now have lower affinity for the active site and are hence released - the active site is available for 2 new substrate molecules.
