41 terms

Mader Biology - Chapter 6 (Metabolism: Energy and Enzymes)

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energy
Ability to do work or bring about change; allows living things to carry on the processes of life, including growth, development, metabolism, and reproduction.
kinetic energy
The energy of motion, as when water flows over a waterfall, a ball rolls down a hill, or a moose walks through the grass.
potential energy
Stored energy whose capacity to accomplish work is not being used at the moment.
chemical energy
Energy associated with the interaction of atoms in a molecule.
mechanical energy
A type of kinetic energy associated with the position, or motion (such as walking or running) of an object.
heat
Type of kinetic energy associated with the random motion of molecules.
laws of thermodynamics
Two laws explaining energy and its relationships and exchanges.
entropy
Measure of disorder or randomness in a system.
metabolism
The sum of the chemical reactions that occur in a cell.
reactant(s)
Substance that participates in a reaction.
product(s)
Substance that forms as a result of a reaction.
free energy
The amount of energy left to do work after a chemical reaction has occurred.
exergonic reaction(s)
Spontaneous chemical reaction that releases energy.
endergonic reaction(s)
Chemical reaction that requires an input of energy to occur.
adenosine triphosphate
Nucleotide with three phosphate groups.
adenosine diphosphate
Nucleotide with two phosphate groups.
mole
A unit of measurement in chemistry; equal to the molecular weight of a molecule expressed in grams.
enzyme
Protein molecule that functions to speed a chemical reaction without itself being affected by the reaction.
ribozyme(s)
RNA molecule that is capable of catalyzing specific biochemical reactions, similar to the action of protein enzymes. These molecules are involved in the synthesis of RNA and the synthesis of proteins in ribosomes.
metabolic pathway
Series of linked reactions, beginning with a particular reactant and terminating with an end product.
energy of activation (Ea)
Energy that must be added in order for molecules to react with one another.
substrates
Reactant in an enzyme-controlled reaction.
active site
Region of an enzyme where the substrate binds and where the chemical reaction occurs.
induced fit model
The enzyme is induced to undergo a slight alteration to achieve optimum fit for the substances.
denatured
Loss of a protein's or enzyme's normal shape so that it can no longer bind its substrate(s) efficiently; caused by a pH and/or temperature beyond the optimal ranges for the enzyme.
cofactors
Non-protein assistant required by an enzyme in order to function; many are metal ions while others are coenzymes.
coenzyme(s)
Non-protein organic molecule that aids the action of the enzyme to which it is loosely bound.
vitamin(s)
Organic nutrient that is required in small amounts for metabolic functions. Often part of coenzymes.
enzyme inhibition
Means by which cells regulate enzyme activity; occurs when a molecule (the inhibitor) binds to an enzyme and decreases its activity.
noncompetitive inhibition
Form of enzyme inhibition where the inhibitor binds to an enzyme at a location other than the active site; while at this site, the enzyme shape changes, the enzyme is unable to bind to its substrate, and no product forms.
allosteric site
Site other than the active site where an inhibitor can bind and the active site of the enzyme changes shape, which in turn changes its function.
competitive inhibition
Form of enzyme inhibition where the substrate and inhibitor are both able to bind to the enzyme's active site. Only when the substrate is at the active site will product form.
oxidation-reduction reaction
A paired set of chemical reactions in which one molecule gives up electrons (oxidized) while another molecule accepts electrons (reduced); commonly called a redox reaction.
oxidation
Loss of one or more electrons from an atom or molecule; in biological systems, generally the loss of hydrogen atoms.
reduction
Gain of electrons by an atom or molecule with a concurrent storage of energy; in biological systems, the electrons are accompanied by hydrogen ions.
redox reaction(s)
A paired set of chemical reactions in which one molecule gives up electrons (oxidized) while another molecule accepts electrons (reduced); also called an oxidation-reduction reaction.
NADP+ (Nicotinamide Adenine Dinucleotide Phosphate)
Coenzyme in oxidation-reduction reactions that accepts electrons and hydrogen ions to become NADPH + H+. During photosynthesis, NADPH participates in the reduction of carbon dioxide to a carbohydrate.
NAD+ (Nicotinamide Adenine Dinucleotide)
Coenzyme in oxidation-reduction reactions that accepts electrons and hydrogen ions to become NADH + H+ as oxidation of substrates occurs. During cellular respiration, NADH carries electrons to the electron transport chain in mitochondria.
electron transport chain (ETC)
Process in a cell that involves the passage of electrons along a series of membrane-bound electron carrier molecules from a higher to lower energy level; the energy released is used for the synthesis of ATP.
ATP synthases
Process where protons can move back across the membrane by interacting with other enzyme complexes in the membrane.
chemiosmosis
The production of ATP due to a hydrogen ion gradient across a membrane.