Human Biology Chapter 2

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.

Front 2

matter

Back 2

anything that takes up space and has mass, made up of atoms.

Front 3

atom

Back 3

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

Front 4

element

Back 4

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

Front 5

isotope

Back 5

atoms that have the same number of proteins but different number of neutrons.

Front 6

radioisotope

Back 6

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

Front 7

compound

Back 7

a molecule that contains two or more different elements.

Front 8

covalent bond

Back 8

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

Front 9

molecule

Back 9

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

Front 10

ion

Back 10

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

Front 11

ionic bond

Back 11

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

Front 12

hydrogen bond

Back 12

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.

Front 13

acid

Back 13

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

Front 14

base

Back 14

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

Front 15

pH scale

Back 15

a scale for measuring the concentration of hydrogen ions. The scale ranges from to 14, with a pH of 7 being neutral, a pH of less than 7 being acidic, and a pH of greater than 7, basic.

Front 16

pH

Back 16

measure of hydrogen ion concentration

Front 17

buffer

Back 17

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.

Front 18

macromolecules

Back 18

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

Front 19

polymer

Back 19

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

Front 20

monomer

Back 20

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

Front 21

dehydration synthesis

Back 21

the process by which polymers are formed. monomers are linked together through the removal of a water molecule.

Front 22

hydrolysis

Back 22

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

Front 23

carbohydrate

Back 23

an organic molecule that provides fuel fo rht ehuman body. which we know as sugars and starches, can be classified by size into the monsaccharides, disaccharides, and the polysaccharides.

Front 24

monosaccharide

Back 24

the smallest molecular unit of a carbohydrate, known as simply sugars.

Front 25

disaccharide

Back 25

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

Front 26

polysaccharide

Back 26

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

Front 27

starch

Back 27

the storage of polysaccharide in plants.

Front 28

glycogen

Back 28

the storage of polysaccharide in animals.

Front 29

cellulose

Back 29

a structural polysaccharide found in the cell walls of plants. humans lack 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 fiber known to facilitate the passages of feces through the large intestines.

Front 30

lipid

Back 30

a compound, such as a triglyceride, phospholipid, or steroid, that does not dissolve in water.

Front 31

triglyceride

Back 31

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

Front 32

phospholipid

Back 32

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

Front 33

steroid

Back 33

a lipid, such as cholesterol, consisting of four carbon rings with functional groups attached.

Front 34

protein

Back 34

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

Front 35

amino acid

Back 35

the building blocks of proteins consisting of a 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 important to human life; some can be synthesized by our bodies (nonessential) and some cannot be synthesized and must be obtained from the foods we eat (essential).

Front 36

peptide

Back 36

a chain containing only a few amino acids.

Front 37

polypeptide

Back 37

a chain containing 10 or more amino acids.

Front 38

primary structure

Back 38

the precise sequence of amino acids of a protein. this sequence, determined by the genes, dictates a protein's structure and function.

Front 39

secondary structure

Back 39

the bending and folding of the chain of amino acids of a protein to produce shapes such as coils, spirals, and pleated sheets. these shapes form as a result of hydrogen bonding between different parts of the polypeptide chain.

Front 40

tertiary structure

Back 40

the three-dimensional shape of proteins formed by hydrogen, ionic, and covalent bonds between different side chains.

Front 41

denaturation

Back 41

the process by which changes in teh environment of protein, such as increased heat of changes in pH, cause it to unravel and lose its three-dimensional shape. Change in the shape of a protein results in loss of function.

Front 42

quaternary structure

Back 42

the shape of an aggregate protein. it is determined by the mutually attractive forces between protein's subunits.

Front 43

enzyme

Back 43

a substance (usually a protein, but sometimes an RNA molecule)
that speeds up chemical reactions without being consumed in the process.

Front 44

active site

Back 44

a specific location on an enzyme where the substrate binds.

Front 45

enzyme-substrate complex

Back 45

a complex formed when a substrate binds to an enzyme at the active site.

Front 46

deoxyribonucleic acids (DNA)

Back 46

the molecular basis of genetic inheritance in all cells and some viruses. a category of nucleic acids that usually consists of a double helix of two nucleotide strands. the sequence of nucleotides carries the instructions for assembling proteins.

Front 47

ribonucleic acid (RNA)

Back 47

a single-stranded nucleic acid that contains ribose (a five-carbon sugar, phosphate, adenine, uracil, cytosine, or guanine. It plays a variety of roles in protein synthesis.

Front 48

nucleotide

Back 48

a subunit of DNA composed of one five-carbon sugar (either ribose or deoxyribose), one phosphate group, and one of five nitrogen-containing bases. They are the building blocks of nucleic acids.

Front 49

adenosine triphosphate

Back 49

a nucleotide that consists of the sugar ribose, the base adenine, and three phosphate groups. it is the energy currency of all living cells.