Molecules of Life

Question 1

Carbohydrate

Answer 1

any of a class of organic compounds that change to such substances on simple chemical transformations, as hydrolysis, oxidation, or reduction, and that form the supporting tissues of plants and are important food for animals and people.

Question 2

Monosaccharide

Answer 2

a carbohydrate that does not hydrolyze, as glucose, fructose, or ribose, occurring naturally or obtained by the hydrolysis of glycosides or polysaccharides.

Question 3

Disaccharide

Answer 3

any of a group of carbohydrates, as sucrose or lactose, that yield monosaccharides on hydrolysis.

Question 4

Polysaccharide

Answer 4

a carbohydrate, as starch, or cellulose, containing more than three monosaccharide units per molecule, the units being attached to each other in the manner of acetals, and therefore capable of hydrolysis by acids or enzymes to monosaccharides.

Question 5

Lipid

Answer 5

any of a group of organic compounds that are greasy to the touch, insoluble in water, and soluble in alcohol and ether: lipids comprise the fats and other esters with analogous properties and constitute, with proteins and carbohydrates, the chief structural components of living cells.

Question 6

Phospholipid

Answer 6

any of a group of fatty compounds, as lecithin, composed of phosphoric esters, and occurring in living cells.

Question 7

Wax

Answer 7

any of a group of substances composed of hydrocarbons, alcohols, fatty acids, and esters that are solid at ordinary temperatures.

Question 8

Steroid

Answer 8

any of a large group of fat-soluble organic compounds, as the sterols, bile acids, and sex hormones, most of which have specific physiological action.

Question 9

Functional Group

Answer 9

a group of atoms responsible for the characteristic behavior of the class of compounds in which the group occurs, as the hydroxyl group in alcohols.

Question 10

Polymer

Answer 10

a compound of high molecular weight derived either by the addition of many smaller molecules, as polyethylene, or by the condensation of many smaller molecules with the elimination of water, alcohol, or the like, as nylon.

Question 11

Monomer

Answer 11

a molecule of low molecular weight capable of reacting with identical or different molecules of low molecular weight to form a polymer.

Question 12

Dehydration

Answer 12

an abnormal loss of water from the body, especially from illness or physical exertion.

Question 13

Nucleic Acid

Answer 13

any of a group of long, linear macromolecules, either DNA or various types of RNA, that carry genetic information directing all cellular functions: composed of linked nucleotides.

Question 14

Condensation Reaction

Answer 14

A condensation reaction, is a chemical reaction in which two molecules combine to form a larger molecule, together with the loss of a small molecule.

Question 15

RNA

Answer 15

ribonucleic acid: any of a class of single-stranded molecules transcribed from DNA in the cell nucleus or in the mitochondrion or chloroplast, containing along the strand a linear sequence of nucleotide bases that is complementary to the DNA strand from which it is transcribed: the composition of the RNA molecule is identical with that of DNA except for the substitution of the sugar ribose for deoxyribose and the substitution of the nucleotide base uracil for thymine.

Question 16

DNA

Answer 16

Genetics. deoxyribonucleic acid: an extremely long macromolecule that is the main component of chromosomes and is the material that transfers genetic characteristics in all life forms, constructed of two nucleotide strands coiled around each other in a ladderlike arrangement with the sidepieces composed of alternating phosphate and deoxyribose units and the rungs composed of the purine and pyrimidine bases adenine, guanine, cytosine, and thymine: the genetic information of DNA is encoded in the sequence of the bases and is transcribed as the strands unwind and replicate.
Compare base pair, gene, genetic code, RNA.

Question 17

Nucleotide

Answer 17

any of a group of molecules that, when linked together, form the building blocks of DNA or RNA: composed of a phosphate group, the bases adenine, cytosine, guanine, and thymine, and a pentose sugar, in RNA the thymine base being replaced by uracil.

Question 18

Adenosine Triphosphate

Answer 18

ATP

Question 19

Isomer

Answer 19

a compound displaying isomerism with one or more other compounds.

Question 20

Synthesis

Answer 20

Chemistry. the forming or building of a more complex substance or compound from elements or simpler compounds.

Question 21

Hydrolysis

Answer 21

chemical decomposition in which a compound is split into other compounds by reacting with water.

Question 22

Protein

Answer 22

Biochemistry. any of numerous, highly varied organic molecules constituting a large portion of the mass of every life form and necessary in the diet of all animals and other nonphotosynthesizing organisms, composed of 20 or more amino acids linked in a genetically controlled linear sequence into one or more long polypeptide chains, the final shape and other properties of each protein being determined by the side chains of the amino acids and their chemical attachments: proteins include such specialized forms as collagen for supportive tissue, hemoglobin for transport, antibodies for immune defense, and enzymes for metabolism.

Question 23

Amino Acid

Answer 23

any of a class of organic compounds that contains at least one amino group, –NH 2 , and one carboxyl group, –COOH: the alpha-amino acids, RCH(NH 2)COOH, are the building blocks from which proteins are constructed.

Question 24

Substrate

Answer 24

the substance acted upon by an enzyme.

Question 25

Macromolecule

Answer 25

A very large molecule, as a protein, or especially a polymer, composed of hundreds or thousands of atoms.

Question 26

Polypeptide

Answer 26

a chain of amino acids linked together by peptide bonds and having a molecular weight of up to about 10,000.

Question 27

Enzyme

Answer 27

any of various proteins, as pepsin, originating from living cells and capable of producing certain chemical changes in organic substances by catalytic action, as in digestion.

Question 28

Active Site

Answer 28

the part of an enzyme that interacts with the substrate during catalysis.

Question 29

Peptide bond

Answer 29

a covalent bond formed by joining the carboxyl group of one amino acid to the amino group of another, with the removal of a molecule of water.