Human Biology Chapter Two

Front 1

chemistry

Back 1

the branch of science concerned with the composition and properties of material substances, including their abilities to change into other substances.

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matter

Back 2

anything that takes up space and mass. it is made up of atoms

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atom

Back 3

a unit of matter that cannot be further broken down by chemical means; it is composed of subatomic particles, which include protons, neutrons, and electrons.

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element

Back 4

any substance that cannot be broken down into simpler substances by ordinary chemical means.

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isotope

Back 5

atoms that have the same number of protons but different numbers of neutrons.

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radioisotope

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isotopes that are unstable and spontaneously decay emitting radiationin the form of gamma rays and alpha and beta particles.

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compound

Back 7

a molecule that contains two or more different elements.

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covalent bond

Back 8

a chemical bond formed when outer shell electrons are shared between atoms.

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molecule

Back 9

a chemical structure composed of atoms held together by covalent bonds.

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ion

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an atom or group of atoms that carries an electric charge resulting from the loss or gain of electrons.

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ionic bond

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a chemical bond that results from the mutual attractions of oppositely charged ions.

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hydrogen bond

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a weak chemical bond formed between a partially positively charged hydrogen atom in a molecule and a partially negatively charged atom in another molecule or in another region of the same molecule.

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acid

Back 13

any substance that increases the concentration of hydrogen ions in solution.

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base

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any substance that reduces the concentration of hydrogen ions in solution.

Front 15

pH

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a scale for measuring the concentration of hydrogen ions. the scale ranges from 0-14 with ph of 7 being neutral below acidic and above basic.

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buffer

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a substance that prevents dramatic changes in pH by removing excess hydrogen ions from solution when concentrations increase and adding hydrogen ions when concentrations decrease.

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macromolecule

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a giant molecule of life such as a nucleic acid, protein or polysaccharide. formed by the joining together of smaller molecules.

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polymer

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a large molecule formed by the joining together of many smaller molecules of the same general type. (monomers).

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monomer

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a small molecule that joins with identical molecules to form a polymer.

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dehydration synthesis

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the process by which changes in the environment of a protein, sucha as increased heat or changes in pH, cause it to unravel and lose its tree-dimensional shape. change in the shape of a protein results in loss of function.

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hydrolysis

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the process by which polymers are broken apart by the addition of water.

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carbohydrate

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an organic molecule that provides fuel for the human body, sugars and starches. can be classified by size intothe monosaccharides, dissaccharides, and polysaccharides.

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monosaccharide

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the smallest molecular unit of carbohydrate, simple sugars.

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disaccharide

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a molecule formed when two monosaccharides covalently bond to each other through dehydration synthesis, double sugar.

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polysaccharide

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a complex carbohydrate formed when large numbers of monosaccharides (most commonly glucose) join together to form a long chain through dehydration synthesis. most store energy or provide structure.

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starch

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the storage polysaccharide in plants

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cellulose

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a structural polysaccharide found in the cell walls of plants. humans lack the enzymes necessary to digest it, and thus it passes unchanged through our digestive tract. although it has no value as a nutrient, it is an important form of dietary fiver known to facilitate the passage of feces through the large intestines.

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lipid

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a compound, such as a triglyceride, phospholipid, or steroid, that does ot dissolve in water.

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triglyceride

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the lipids composed of one molecule of glycerol and three fatty acids, they are known as fats when solid and oils when liquid.

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phospholipid

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an important component of cell membranes. it has a nonpolar "water-fearing" tail (made up of fatty acids) and a polar "water-loving" head (containing an R group, glycerol, and phosphate.)

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steroid

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a lipid, sucha s cholesterol, consisting of four carbon rings with functional groups attached.

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protein

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the macromolecules composed of amino acids linked by peptide bonds, the functions of proteins include structural supports, transport, movement, and regulation of chemical reactions.

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amino acid

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the building blocks of proteins consisting of central carbon atom bound to a hydrogen atom, an amino group, a carboxyl group, and a side chain designated by the letter R. there are 20 of these important to human life, some can be synthesized by our bodies )nonessential_, whereas others cannot be synthesized and must be obtained from the foods we eat (essential).

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peptide

Back 34

a chain containing only a few amino acids.