Biology - Energy and Metabolism

acetyl coA

short for acetyl coenzyme A; formed from a fragment of pyruvate bonded to a coenzyme before the citric acid cycle begins

activation Energy

the energy requirement needed for reactants to undergo a chemical reaction

active Site

the part of an enzyme where its substrate binds

aerobic respiration

breakdown of organic molecules to produce ATP using oxygen

allosteric regulation

regulatory molecule binds to a protein at one site which then affects the function at another site

anabolism

refers to metabolic pathways that build things up from smaller components

anaerobic respiration

production of ATP by breaking down organic molecules without the use of oxygen

ATP synthase

a protein “pump” which uses a hydrogen ion gradient to phosphorylate ADP to ATP

catabolism

refers to metabolic pathways that break things down from big to small

catalyst

a chemical that increases a reaction rate without being consumed by reducing the activation energy of a reaction

chemiosmosis

describes an energy coupling pair where a hydrogen ion gradient is formed and then used to do work

coenzyme

an organic cofactor

cofactor

a helper molecule: any nonprotein molecule that an enzyme needs to function

competitive inhibition

inhibition where a substance reduces enzyme activity by binding to the active site

cooperativity

a type of allosteric regulation where the substrate binds to enzyme and other subunits of the protein change shape which facilitates the binding of more substrates to the other subunits

cristae

the membrane folds within mitochondria

electrochemical gradient

diffusion gradient of an ion

electron transport chain

a sequence of redox reactions that release energy used to make ATP

endergonic

describes a chemical reaction that absorbs free energy from the surroundings

energy coupling

use the energy released from an exergonic reaction to provide the energy needed to drive an endergonic reaction forward

entropy

a measure of disorder

enzyme

a biological molecule that acts as a catalyst

exergonic

describes a chemical reaction that releases free energy to the surroundings

FAD / FADH2

an electron carrier in the electron transport chain

feedback inhibition

a regulatory system where the result of a reaction inhibits the pathway

fermentation

catabolic process that produces ATP from glucose without using the electron transport chain; produces an end product such as lactic acid

first law of thermodynamics

conservation of energy; energy cannot be created nor destroyed but can only be transferred and transformed

free energy

the portion of a biological system’s energy that can be used for work

G3P

a carbon intermediate that is produced during from glucose and is then turned into pyruvate

glycolysis

splitting of glucose into two pyruvates as a starting step for either cellular respiration or fermentation

kinetic energy

energy of motion

krebs / citric acid cycle

a cycle that completes the breakdown of glucose by oxidizing pyruvate to carbon dioxide

matrix

mitochondrion compartment enclosed by inner membrane

metabolic pathway

refers to a series of chemical reactions which may be anabolic or catabolic

mitochondria

the “powerhouse” of the cell; organelle that serves as the site for cellular respiration

NAD+ / NADH

an electron carrier in the electron transport chain

noncompetitive inhibition

inhibition where a substance reduces enzyme activity by binding to a location that is not the active site

nonspontaneous

a reaction that will not move proceed unless additional energy is added

oxidation

a substance that is oxidized loses electrons

oxidative phosphorylation

ATP production using energy from the redox reactions of the electron transport chain

phosphorylation

a reaction that adds a phosphate group to a molecule

positive feedback

a loop where the end result of a reaction amplifies the reaction

pyruvate

carbon intermediate that results from the breakdown of glucose which is produced during glycolysis

second law of thermodynamics

the universe tends to move towards higher entropy

spontaneous

a reaction that will move proceed without additional energy input

substrate level phosphorylation

a reaction where an intermediate substrate is catabolized, and an enzyme phosphorylates ADP to ATP

substrate

the reactant that binds to an enzyme

thermal energy

energy of heat; kinetic energy of moving atoms and molecules