Anatomy Chapter 5 Vocab

Metabolism: Energy and Enzymes

metabolism

the sum of all the chemical reactions that occur in a cell

catabolism

the breaking down of molecules

anabolism

the building up (synthesis) of molecules

reactants

in a chemical reaction, the substances that participate in a reaction

products

in a chemical reaction, the substances that form as a result of a reaction

free energy

the amount of energy available after a chemical reaction as occurred; also called ΔG

exergonic reactions

reactions that are spontaneous and release energy

endergonic reactions

reactions that require an input of energy to occur

ATP (adenosine triphosphate)

the common energy currency of cells; supplies energy for chemical work, transport work, and mechanical work by being converted to ADP plus a phosphate group

ADP (adenosine diphosphate)

a nucleotide that can accept another phosphate group and become ATP

metabolic pathway

a series of linked reactions that begin with a particular reactant and terminate with an end product

enzymes

types of proteins that function as catalysts to speed up chemical reactions

substrates

reactants in an enzymatic reaction

energy of activation (E_a)

the energy that must be added to cause molecules to react with one another

active site

a small part of an enzyme that forms a complex with a substrate(s)

induced fit model

when the enzyme undergoes a slight change in shape in order to accommodate the substrate

denatured

describes a protein that has had an irreversible change in its shape; occurs when proteins are exposed to extremes in heat and pH

enzyme inhibition

occurs when the substrate is unable to bind to the active site of an enzyme

cofactors

inorganic ion helpers required by enzymes to function properly

coenzymes

organic, nonprotein molecule helpers required by enzymes to function properly

vitamins

relatively small organic molecules that are required in trace amounts in diets for synthesis of coenzymes that affect health and physical fitness

thyroid gland

a large gland in the neck that produces several important hormones, including triiodothyronine, thyroxine, and calcitonin

parathyroid glands

glands embedded behind the thyroid gland; produce parathyroid hormones

thyroxine (T₄)

a hormone produced by the thyroid gland that increases metabolic rate

triiodothyronine (T₃)

a hormone produced by the thyroid gland that increases metabolic rate

calcitonin

a hormone produced by the thyroid gland that helps control blood calcium levels

parathyroid glands

glands embedded behind the thyroid gland; produce parathyroid hormones

parathyroid hormone (PTH)

hormone produced by the parathyroid glands; causes the blood phosphate level to decrease and the blood calcium level to increase