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Bio Chapter 8
Term | Definition |
---|---|
Bacteriophage | A virus that infects bacteria |
Nucleotide | An organic compound that consist of a 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 pairs 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 template |
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 a stop signal |
Stop codon | Codon that signal 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 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 charge 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 |