The purpose of this glossary is to help reader better understand the terms used in the field of biotechnology.


  • tRNA (transfer RNA)

    RNA that transports amino acids to the ribosomes, where the amino acids are assembled into proteins
  • Amino acid

    An acid containing the amino group NH2 and a carboxyl (COOH) group, and having the basic formula NH2 - CR - COOH. The sequence of amino acids determines the shape, properties and the biological role of a protein. Plants and many micro-organisms can synthesize amino acids from simple inorganic compounds, but animals are unable to synthesize some of them, called essential amino acids, so they must be present in the diet
  • Antibiotic

    A class of natural and synthetic compounds that inhibit the growth of or kill some micro-organisms. Antibiotics such as penicillin are often used to control (to some extent kill) contaminating organisms
  • Antibody

    An immunological protein (called an immunoglobulin, Ig) produced by certain white blood cells (lymphocytes) of the immune system of an organism in response to a contact with a foreign substance (antigen). Immunoglobulin can be grouped into 5 classes: IgA, IgD, IgE, IgG, IgM
  • Antiviral

    Any medicine capable of destroying or weakening a virus
  • Autosome

    A chromosome that is not involved in sex determination
  • Cell differentiation

    Continuous loss of physiological and cytological characters of young cells, resulting in getting the characters of adult cells. The unspecialized cells become modified and specialized for the performance of specific functions
  • Chromosomal aberration

    Or chromosomal mutation: any change in chromosome structure or number
  • Chromosome

    A single DNA molecule, a tightly coiled strand of DNA. Chromosomes exist in pairs in eukaryotes - one paternal (from the male parent) and one maternal (from the female parent). Each eukaryotic species has a characteristic number of chromosomes: human somatic cells contain 22 pairs of autosomes plus two sex chromosomes, for a total of 46 chromosomes (diploid chromosome number)
  • Clone

    A group of cells or organisms that are genetically identical as a result of asexual reproduction, breeding of completely inbred organisms
  • Codon

    A set of three nucleotides in mRNA, functioning as a unit of genetic coding by specifying a particular amino acid during the synthesis of polypeptides in a cell. A codon specifies a transfer RNA carrying a specific amino acid, which is incorporated into a polypeptide chain during protein synthesis
  • Complementarity

    The relationship between the two strands of a double helix of DNA. Adenine in one strand always pairs with thymine in the other strand (or with uracil, in the case of RNA), and cytosine in one strand pairs always with guanine in the other strand (and vice versa)
  • Deletion

    A mutation involving the removal of one or more base pairs in DNA sequence
  • Denaturation

    Loss of native configuration of a macro-molecule (protein or nucleic acid) by physical or chemical means, usually accompanied by loss of biological activity
  • Deoxyribonucleic acid

    See DNA
  • DNA (deoxyribonucleic acid)

    The long chain of molecules in most cells that carries the genetic message and controls all cellular functions in most forms of life. The information-carrying genetic material that comprises the genes. DNA is a macro-molecule composed of a long chain of deoxyribonucleotides joined by phospho-diester linkages. Each deoxyribonucleotide contains a phosphate group, the five-carbon sugar 2-deoxribose, and a nitrogen-containing base. The genetic material of most organisms and organelles so far examined is double-stranded DNA, in which two strands run in opposite (anti-parallel) directions and are coiled round one another in a double helix. Purine bases on one strand specifically hydrogen bond with pyrimidine bases on the other strand, according to the Watson-Crick rules (A pairs with T; G pairs with C)
  • Electrophoresis

    A technique that separates charged molecules - such as DNA, RNA or protein - on the basis of relative migration in an appropriate matrix (such as agarose gel or polyacrylamide gel) subjected to an electric field
  • Enzyme

    A protein produced in living cells which catalyzes specific chemical reactions but is not used up in the reaction
  • Eukaryote

    Any cell or organism characterized by having the nucleus enclosed by a membrane
  • Gamete

    A mature reproductive cell which is capable of fusing with a cell of similar origin but of opposite sex to form a zygote from which a new organism can develop. Gametes have a haploid chromosome content. In animals, a gamete is a sperm in male and egg in female
  • Gene

    A segment of nucleic acid that encodes peptide or RNA. Conceptually, it is the unit of heredity transmitted from generation to generation during sexual or asexual reproduction
  • Genetic code

    The set of nucleotide triplets (codons) that specify the 20 amino acids and termination codons (UAA, UAG, UGA). It is also intended as the relationships between the nucleotide base-pair triplets of an mRNA molecule and the 20 amino acids that are the building blocks of proteins. The code is universal, since all living organisms (apart from rare exceptions) use the same genetic code
  • Genetic engineering

    Changes in the genetic constitution of cells (apart from selective breeding) resulting from the introduction or elimination of specific genes through modern molecular biology techniques
  • Genetically modified organism (GMO)

    An organism that has been modified by the application of recombinant DNA technology
  • Genetics

    Term coined by William Bateson in 1906 to indicate the science of heredity and variation, which studies the structure and function of genes, their transmission and how they are distributed among population
  • Genome

    The entire complement of genetic material present in each cell of an organism. A complete set of chromosomes inherited as a (haploid) unit from one parent
  • Genotype

    The genetic constitution (gene makeup) of an organism. The sum total of all pairs of alleles at all loci that contribute to the expression of a quantitative trait
  • Human Genome Project

    An international project that mapped and sequenced the entire human genome; the main goals of the Human Genome Project were to provide a complete and accurate sequence of the 3 billion DNA base pairs that make up the human genome, to find all of the estimated 20,000 to 25,000 human genes, to develop new tools to obtain and analyze the data and to make this information widely available, to explore the consequences of genomic research through its Ethical, Legal, and Social Implications (ELSI) program
  • In vitro

    Living in test tubes, outside the organism or in an artificial environment, typically in glass vessels in which cultured cells, tissues, organs or whole plants may reside
  • In vivo

    The natural conditions in which organisms reside. Refers to biological processes that take place within a living organism or cell under normal conditions
  • Locus (pl: loci)

    A site on a chromosome
  • Meiosis

    The special cell division process by which the chromosome number of a reproductive cell becomes reduced to half (n) the diploid (2n) or somatic number. Two consecutive divisions occur. In the first division, homologous chromosomes became paired and may exchange genetic material (via crossing over) before moving away from each other into separate daughter nuclei (reduction division). These new nuclei divide by mitosis to produce four haploid nuclei
  • Mendelian inheritance

    The transmission of particular characteristics and/or genes from generation to generation according to Mendel’s laws
  • Mitosis

    Disjunction of replicated chromosomes and division of the cytoplasm to produce two genetically identical daughter cells. The division involves the appearance of chromosomes, their longitudinal duplication, and equal distribution of newly formed parts to daughter nuclei
  • mRNA (messenger RNA)

    The RNA transcript of a protein-encoding gene. The information encoded in the mRNA molecule is translated into a polypeptide of specific amino acid sequence by the ribosomes. In eukaryotes, mRNAs transfer genetic information from the DNA to ribosomes, where it is translated into protein
  • Mutant allele

    An allele that differs from the wild type because it carries one or more genetic changes in its DNA
  • Mutation

    A sudden, heritable change appearing in an individual as the result of a change in the structure of a gene (gene mutation); changes in the structure of chromosomes (chromosome mutation); or in the number of chromosomes (genome mutation)
  • Nitrogenous bases

    The purines (adenine and guanine) and pyrimidines (cytosine and thymine in DNA or uracil in RNA) that form DNA and RNA molecules
  • Nucleoside

    A base (purine or pyrimidine) that is covalently linked to a 5-carbon (pentose) sugar (deoxyribose in DNA, ribose in RNA). Adenine, guanine and cytosine occur in both DNA and RNA; thymine occurs in DNA; and uracil in RNA. They are the building blocks of DNA and RNA
  • Nucleotide

    A nucleoside with one or more phosphate groups linked to the 5´ carbon of the pentose sugar
  • Oligonucleotide

    A short molecule (usually 6 to 100 nucleotides) of single-stranded DNA
  • PCR (Polymerase Chain Reaction)

    A procedure that amplifies a particular DNA sequence. It involves multiple cycles of denaturation, annealing to oligonucleotide primers, and extension (polynucleotide synthesis)
  • Phenotype

    The visible appearance or set of traits of an organism resulting from the combined action of genotype and environment
  • Plasmid

    An extrachromosomal, autonomous circular DNA molecule found in certain bacteria, capable of autonomous replication. Plasmids can transfer genes between bacteria and are important tools of transformation in genetic engineering. They exist in an autonomous state and are transferred independently of chromosomes
  • Prokaryote

    A member of a large group of organisms, including bacteria and blue-green algae, which do not have the DNA separated from the cytoplasm by a membrane in their cells. The DNA is usually in one long strand. Prokaryotes do not undergo meiosis and do not have functional organelles such as mitochondria and chloroplasts
  • Protein

    A macromolecule composed of one to several polypeptides. Each polypeptide consists of a chain of amino acids linked together by covalent (peptide) bonds
  • Recombinant DNA

    DNA artificially constructed by combining genes from different organisms or by cloning chemically altered DNA, usually for the purpose of genetic manipulation
  • Ribonucleic acid

    see RNA
  • RNA (ribonucleic acid)

    An organic acid composed of repeating nucleotide units of adenine, guanine, cytosine and uracil, whose ribose components are linked by phospho-diester bonds. More generally, a molecule derived from DNA by transcription that may carry information (messenger RNA (mRNA)), provide sub-cellular structure (ribosomal RNA (rRNA)), transport amino acids (transfer RNA (tRNA)) or facilitate the biochemical modification of itself or other RNA molecules
  • Sex chromosomes

    Chromosomes that are connected with the determination of sex; in mammals, there are two X chromosomes in females and one X and one Y chromosome in males
  • Stem cell

    An undifferentiated active somatic cell that undergoes division and gives rise to other stem cells or to cells that differentiate to form specialized cells
  • Syndrome

    A group of symptoms that occur together and represent a particular disease
  • Transgenic

    An organism in which a foreign gene (a transgene) is incorporated into its genome. The transgene is present in both somatic and germ cells, is expressed in one or more tissues, and is inherited by offspring in a Mendelian fashion
  • Translation

    The process of polypeptide synthesis in which the amino acid sequence is determined by mRNA, mediated by tRNA molecules, and carried out on ribosomes
  • Trisomy

    An otherwise diploid cell or organism that has an extra chromosome of one pair (chromosome formula: 2n + 1)
  • Wild type

    An organism as found in nature; the dominant allele usually found in nature, and from which mutations produce other dominants or recessives alleles
  • Zygote

    A diploid cell formed by the fusion of two haploid gametes during fertilization in eukaryotic organisms with sexual reproduction. It is the first cell of the new individual