| Term | Definition |
| transformation | process in which one strain of bacteria appears to change into another one |
| bacteriophage | virus that infects and kills bacteria |
| helix | shape formed by each strand of DNA |
| replication | process in which DNA makes a copy of itself |
| DNA Polymerase | the principal enzyme involved in DNA replication |
| histone | protein that DNA wraps around in eukaryotic chromosomes |
| promoter | signal in DNA that indicates to enzymes where to bind to make DNA |
| introns | sections of RNA molecules that are removed before a eukaryotic gene becomes functional |
| codons | three nucleotides that specify a single amino acid to be added to a polypeptide |
| mutation | a change in DNA sequence that affects genetic information |
| expressed gene | gene that is transcribed into RNA |
| operon | a group of genes that is operated together |
| frameshift | shifts the reading frame of the genetic message |
| TATA box | helps position RNA polymerase by marking a point just before the point at which transcription begins |
| mRNA, rRNA, tRNA | the three main types of RNA |
| CGCUAUAGC | GCGAUAUCG (mRNA sequence) |
| transcription | process in which part of the nucleotide sequence of DNA is copied into a complementary sequence in RNA |
| exons | the remaining portions of the cut out introns in RNA molecules |
| deletion | one nucleotide deleted |
| point mutation | affects on particular nucleotide at a single point in the DNA sequence |
| frameshift mutation | where a point mutation involves the insertions or deletions of nucleotide |
| insertion | one nucleotide is inserted |
| operator region | contains several copies of DNA binding protein, it is the region on the gene to which a repressor can bind, preventing transcription of the genes |