Question | Answer |
bacteriophage | a virus that infects bacteria |
nucleotide | an organic compound that consists of sugar, a phosphate, and a nitrogenous base; the basic building block of a nucleic-acid chain |
double helix | the spiral-staircase structure characteristic of the DNA molecule |
base pairing rules | the rules stating that in DNA cytosine pairs with guanine and adenine with thymine and that in RNA cytosine pairs with guanine and adenine pairs with uracil |
replication | process by which DNA is copied |
DNA polymerase | an enzyme that catalyzes the formation of the DNA molecule |
central dogma | theory that states that, in cells, information only flows from DNA to RNA to proteins |
RNA | ribonucleic acid, a natural polymer that is present in all living cells and that plays a role in protein synthesis |
transcription | the process of forming a nucleic acid by using another molecule as a template; particularly the process of synthesizing RNA by using one strand of a DNA molecule as a temeplate |
RNA polymerase | an enzyme that starts (catalyzes) the formation of RNA by using a strand of a DNA molecule as a template |
messenger RNA (mRNA) | form of RNA that carries genetic information from the nucleus to the cytoplasm, where it serves as a template for protein synthesis |
ribosomal RNA (rRNA) | RNA that is in the ribosome and guides the translation of mRNA into a protein; also used as a molecular clock |
transfer RNA (tRNA) | form of RNA that brings amino acids to ribosomes during protein synthesis |
translation | the portion of protein synthesis that takes place at ribosomes and that uses the codons in mRNA molecules to specify the sequence of amino acids in polypeptide chains |
codon | in DNA and mRNA, a three-nucleotide sequence that encodes an amino acid or signifies a start signal or stop signal |
stop codon | codon that signals to ribosomes to stop translation |
start codon | codon that signals to ribosomes to begin translation; codes for the first amino acid in a protein |
anticodon | a region of a tRNA molecule that consists of a sequence of three bases that is complementary to an mRNA codon |
promoter | a nucleotide sequence on a DNA molecule to which an RNA polymerase molecule binds. which initiates the transcription of a specific gene |
operon | a unit of adjacent genes that consists of a functionally related structural genes and their associated regulatory genes; common in prokaryotes and phages |
exon | one of several nonadjacent nucleotide sequences that are part of one gene and that are transcribed, joined together, and then translated |
intron | a nucleotide sequence that is part of a gene and that is transcribed from DNA into mRNA but not translated into amino acids |
mutation | a change in the structure or amount of the genetic material of an organism |
point mutation | a mutation in which only one nucleotide or nitrogenous base in a gene is changed |
frameshift mutation | a mutation, such as the insertion or deletion of a nucleotide in a coding sequence, that results in the misreading of the code during translation because of a change in the reading frame |
mutagen | agent that can induce or increase the frequency of mutation in organisms |