Penn Foster Biology Chapter 3

Front 1

amino acid

Back 1

Organic compound with an amino group (NH2), a carboxylic acid group (COOH), and a side group bonded covalently to the same carbon atom. Subunit of proteins.

Front 2

antioxidant

Back 2

Enzyme or cofactor that can help neutralize free radicals, which may otherwise damage DNA and other molecules of life.

Front 3

archaea

Back 3

Evolutionarily distinct domain of prokaryotic organisms.

Front 4

ATP

Back 4

Adenosine triphosphate. Nucleotide made of adenine, ribose, and three phosphate groups; main energy carrier in cells.

Front 5

cleavage

Back 5

Early stage of animal development. Mitotic cell divisions divide a fertilized egg into many smaller, nucleated cells; original volume of egg cytoplasm does not increase.

Front 6

coenzyme

Back 6

Small molecule that participates in an enzymatic reaction, and is reversibly modified during the reaction (e.g., a vitamin).

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compound

Back 7

Molecule consisting of two or more elements in unvarying proportions.

Front 8

condensation reaction

Back 8

Covalent bonding of two molecules into a larger molecule, often with the formation of water as a by-product.

Front 9

connective tissue

Back 9

Most abundant, pervasive animal tissue. Specialized types are cartilage, bone tissue, adipose tissue, and blood.

Front 10

cytoskeleton

Back 10

Interconnected system of protein filaments that structurally supports, organizes, and moves a eukaryotic cell and its internal structures.

Front 11

denaturation

Back 11

The three-dimensional shape of a protein or some other complex molecule unravels as its hydrogen bonds are disrupted.

Front 12

deoxyribonucleic acid

Back 12

See DNA.

Front 13

disaccharide

Back 13

A common oligosaccharide; two covalently bonded sugar monomers.

Front 14

disease

Back 14

Illness caused by an infectious, dietary, or environmental factor.

Front 15

DNA

Back 15

Deoxyribonucleic acid. Carries the primary hereditary information for all living organisms and many viruses.

Front 16

electron transfer chain

Back 16

Array of membrane-bound enzymes and other molecules that accept and give up electrons in sequence; allows the release and capture of energy in small, useful increments.

Front 17

energy

Back 17

Capacity to do work.

Front 18

enzyme

Back 18

A type of protein (or, rarely, RNA) that accelerates a chemical reaction.

Front 19

fat

Back 19

Type of lipid with a glycerol head attached to one, two, or three fatty acid tails.

Front 20

functional group

Back 20

An atom or a group of atoms with characteristic properties that is covalently bonded to an organic compound’s carbon backbone.

Front 21

hemoglobin

Back 21

Respiratory protein in red blood cells; consists of four polypeptide chains and four heme groups.

Front 22

hydrolysis

Back 22

An enzymatic cleavage reaction in which a molecule is split, and the components of water (—OH and —H) become attached to each of the fragments.

Front 23

induced-fit model

Back 23

An enzyme changes shape to fit a bound substrate, and the resulting tension destabilizes the substrate’s bonds.

Front 24

lipid

Back 24

Nonpolar hydrocarbon; fats, oils, waxes, phospholipids, and sterols are lipids.

Front 25

monosaccharide

Back 25

One of the simple sugars (e.g., glucose) that are unit components of oligosaccharides or polysaccharides.

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mutation

Back 26

Heritable change in DNA.

Front 27

nucleic acid

Back 27

Single-stranded or double-stranded molecule composed of nucleotides joined at phosphate groups (e.g., DNA, RNA).

Front 28

nucleotide

Back 28

Small organic compound with a five-carbon sugar, a nitrogen-containing base, and a phosphate group.

Front 29

organic compound

Back 29

Molecule containing carbon and hydrogen; may also contain oxygen, nitrogen, and other elements.

Front 30

polypeptide chain

Back 30

Three or more amino acids linked by peptide bonds.

Front 31

polysaccharide

Back 31

Straight or branched chain of many covalently linked sugar units of the same or different kinds. Most common types are cellulose, starch, and glycogen.

Front 32

protein

Back 32

Organic compound consisting of one or more polypeptide chains folded and twisted into a three-dimensional shape.

Front 33

ribonucleic acid

Back 33

See RNA.

Front 34

RNA

Back 34

Ribonucleic acid. Any of a class of single-stranded nucleic acids with roles in transcription, translation, and catalysis.

Front 35

sterol

Back 35

Lipid with a rigid backbone of four fused carbon rings.

Front 36

wax

Back 36

A type of lipid with long-chain fatty acids attached to long-chain alcohols or carbon rings.