| A | B |
|---|
| DNA | deoxyribonucleic acid; heredity material that controls all the activities of the cell, contains information to make new cells, and provides instructions to make proteins |
| nucleotide | a subunit of DNA consisting of a sugar, a phosphate, and one of four nitrogenous bases |
| adenine | one of the four bases that combine with sugar and phosphate to form a nucleotide subunit of DNA; this base pairs with thymine |
| thymine | one of the four bases that combine with sugar and phosphate to form a nucleotide subunit of DNA; this base pairs with adenine |
| guanine | one of the four bases that combine with sugar and phosphate to form a nucleotide subunit of DNA; this base pairs with cytosine |
| cytosine | one of the four bases that combine with sugar and phosphate to form a nucleotide subunit of DNA; this base pairs with guanine |
| double helix | twisted ladder |
| complementary | always the opposite of the original |
| replicate | to make a copy of itself |
| ribosome | cellular organelle which manufactures proteins from amino acids |
| mutation | a change in the order of bases in an organism's DNA |
| mutagen | anything that can damage or cause changes in DNA |
| pedigree | a diagram of family history used for tracing a trait through several generations of a family |
| deletion | a base is left out of a DNA sequence |
| insertion | a base is added to a DNA sequence |
| substitution | most common error---an incorrect base replaces a correct base |
| sickle cell anemia | blood disease caused by a substitution in DNA |
| selective breeding | method in which an organism with certain desirable characteristics are mated to produce a new breed |
| genetic engineering | method in which scientists transfer genes from one organism to another; used to manufacture proteins, repair damaged genes, and identify individuals who may carry an allele for a disease; also used in cloning |
