Term | Definition |
Virulent | Describes a microorganism or virus that causes disease and that is highly infectious. |
Transformation | The transfer of genetic material in the form of DNA fragments from one cell to another or from one organism to another. |
Bacteriophage | A virus that infects bacteria. |
Nucleotide | In a nucleic-acid chain, a subunit that consists of a sugar, a phosphate, and a nitrogenous base. |
Deoxyribose | A five-carbon sugar that is a component of DNA nucleotides. |
Nitrogenous Base | An organic base that contains nitrogen, such as a purine or pyrimidine; a subunit of a nucleotide in DNA and RNA. |
Purine | A nitrogenous base that has a double-ring structure; one of the two general categories of nitrogenous bases found in DNA and RNA; either adenine or guanine. |
Pyrimidine | A nitrogenous base that has a single-ring structure; one of the two general categories of nitrogenous bases found in DNA and RNA; thymine, cytosine, or uracil. |
Base-Pairing Rules | The rules stating that cytosine pairs with guanine and adenine pairs with thymine in DNA, and that adenine pairs with uracil in RNA. |
Complementary Base Pair | The nucleotide bases in one strand of DNA or RNA that are paired with those of another strand; adenine pairs with thymine or uracil, and guanine pairs with cytosine. |
Base Sequence | The order of nitrogenous bases on a chain of DNA. |
DNA Replication | The process of making a copy of DNA. |
Helicase | An enzyme that separates DNA strands. |
Replication Fork | A Y-shaped point that results when the two strands of a DNA double helix separate so that the DNA molecule can be replicated. |
DNA Polymerase | An enzyme that catalyzes the formation of the DNA molecule. |
Semi-Conservative Replication | In each new DNA double helix, one strand is from the original molecule, and one strand is new. |
Mutation | A change in the nucleotide-base sequence of a gene or DNA molecule. |
Ribonucleic Acid (RNA) | 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. |
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. |
Protein Synthesis | The formation of proteins by using information contained in DNA and carried by mRNA. |
Ribose | A five-carbon sugar present in RNA. |
Messenger RNA (mRNA) | A single-stranded RNA molecule that encodes the information to make a protein. |
Ribosomal RNA (rRNA) | An organelle that contains most of the RNA in the cell and that is responsible for ribosome function. |
Transfer RNA (tRNA) | An RNA molecule that transfers amino acids to the growing end of a polypeptide chain during translation. |
RNA Polymerase | An enzyme that starts (catalyzes) the formation of RNA by using a strand of a DNA molecule as a template. |
Promoter | A nucleotide sequence on a DNA molecule to which an RNA polymerase molecule binds, which initiates the transcription of a specific gene. |
Termination Signal | A specific sequence of nucleotides that marks the end of a gene. |
Genetic Code | The rule that describes how a sequence of nucleotides, read in groups of three consecutive nucleotides (triplets) that correspond to specific amino acids, specifies the amino acid sequence of a protein. |
Codon | In DNA, a three-nucleotide sequence that encodes an amino acid or signifies a start signal or a stop signal. |
Anticodon | A region of tRNA that consists of three bases complementary to the codon of mRNA. |
Genome | The complete genetic material contained in an individual. |