Complete List of Genetics Terminology | Basic Genetic Terms (A to Z)

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Genetics Terminology A to Z

What is Genetics

Genetics is not only a branch of biology, but also one of the leading sciences of modern natural science. Its developments are used in medicine, genetic engineering, agriculture and industry. The basics of genetics are included in the school curriculum. The term “genetics” was first proposed by the English scientist William Batson in 1905. G. Mendel was considered the founder of genetics. So, genetics is a science that deals with the study of patterns of variability and heredity. It has many different and quite complex terms. Here are some of them:

Complete List of Genetics Terminology

Genetic Terminology :


  • Autosomes:  are chromosomes that do not belong to the sex (X or Y) chromosomes. Humans have 22 pairs of autosomes

  • An Allele: is one of two or more alternative forms of a gene(factor), each of which is characterized by a unique nucleotide sequence; alleles usually differ in nucleotide sequences. Allele is a short form of Allelomorph.

  • Amplicon: is an extrachromosomal unit of amplification.

  • Amplification: an increase in the number of copies of genes (the amount of DNA).

  • Aneuploidy: is an altered set of chromosomes in which one or more chromosomes from the usual set are either absent or represented by additional copies.

  • An anticodon: is a sequence of three nucleotides in a transfer RNA molecule that is complementary to the coding triplet in an mRNA molecule.

  • Autosomal dominant inheritance: is a type of inheritance in which one mutant allele located on the autosome is sufficient for a disease (or trait) to be expressed.

  • Autosomal recessive inheritance: is a type of inheritance for a trait or disease in which a mutant allele located on the autosome must be inherited from both parents.


  • A bacteriophage: is a bacterial virus that consists of DNA or RNA wrapped in a protein coat.

  • A gene bank (library): is a complete set of genes of a given organism, obtained as part of recombinant DNA.

  • Protein engineering: is the creation of artificial proteins with desired properties by directed changes (mutations) in genes or by exchanging loci between heterologous genes.

  • Chorionic biopsy: is a procedure performed at 7-11 weeks of gestation to obtain cells for prenatal diagnosis.

  • Southern blotting: is a method for identifying DNA regions containing sequences complementary to the DNA probe among electrophoretically separated DNA fragments fixed on a solid matrix (nitrocellulose or nylon filters).

  • Blotting: is the transfer of DNA, RNA or protein molecules from the gel in which electrophoresis took place to the filter (membrane).


  • Character : It is a specific feature of an organism e.g. height of stem.
  • Congenital diseases: diseases that are present at birth, can be both hereditary and defects in the individual development of the body.

  • Cloning vector: is any small plasmid, phage, or DNA containing animal virus into which foreign DNA can be inserted.
  • Chromosomal disorder: is an inherited disorder caused by chromosomal abnormalities.
  • Chromosome: is a DNA molecule wrapped in a special way with various proteins that help manage such a long molecule so that it does not break, does not get mixed up with other DNA molecules and is physically accessible to proteins that carry out the work of the entire genetic apparatus.
  • Chromosomal aberration (or chromosomal anomaly): is a generalized name for any of the types of chromosomal mutations: deletions, translocations, inversions, duplications. Sometimes genomic mutations are also indicated (aneuploidy, trisomy, etc.).

  • Chimeras: are laboratory hybrids (recombinants).

  • Chromatin: is a filamentous deoxyribonucleoprotein (DNP) complex molecule that consists of DNA bound to histones.

  • Centromere: is a locus on a chromosome that is present in center. It is physically necessary for the distribution of homologous chromosomes among daughter cells.

  • cDNA: is a single-stranded DNA synthesized in vivo from an RNA template using reverse transcriptase.

  • A clone: is a group of genetically identical cells that originated asexually from a common ancestor.

  • DNA cloning: is the process of obtaining recombinant DNA molecules by inserting foreign DNA into a vector DNA or RNA molecule and introducing this construct into phage, bacterial or eukaryotic host cells.

  • A codon: is a triple of consecutive nucleotide residues in DNA or RNA that codes for a specific amino acid.

  • Conjugation: is a method of exchanging genetic information in bacteria, in which, due to physical contact between cells, cellular, plasmid or transposon DNA is transferred from a donor cell to a recipient cell.

  • Cosmid: is a vector containing cos-site of DNA of phage λ.

  • Crossing over: is the phenomenon of the exchange of sections of homologous chromosomes during conjugation during meiosis


  • Dominant : It is an allele that expresses its trait even in the presence of an alternative allele i.e. in heterozygous condition only. Alternatively, the allele that expresses in F1 is called dominant.
  • Deletion: a type of chromosomal mutation in which a portion of a chromosome is lost; a type of gene mutation in which a portion of a DNA molecule is missing.

  • Denaturation: is a violation of the spatial structure of a molecule as a result of breaking intra- or intermolecular non-covalent bonds. 

  • Duplication: a type of chromosomal mutation in which any part of the chromosome is doubled; a type of gene mutation in which a piece of DNA is duplicated.

  • The sequence of DNA: is the order in which its structural elements, the nucleotides, appear in the DNA molecule. Thus, the DNA sequence is genetic information, and the DNA molecule is its physical carrier.


  • Exon: Coding regions of genes.

  • Exonuclease: is an enzyme that hydrolyzes phosphodiester bonds from the ends of DNA.

  • An explant: is a tissue material isolated from the body.

  • Electrophoresis: is the separation of electrically charged polymers in an electric field. It is usually carried out in gels (gel electrophoresis) so that the zones of the molecules to be separated are not blurred by thermal motion.

  • Endonuclease: is an enzyme that hydrolyzes phosphodiester bonds within the DNA strand.

  • An enhancer: is a regulatory region of DNA that enhances transcription from the promoter closest to it.

  • Epistasis: a type of interaction of non-allelic genes, in which one gene suppresses the expression of another (or other) genes

  • Eukaryotes: are organisms whose cells contain nuclei.


  • Factor : It is a unit of heredity, a particle present in the organism which is responsible for the inheritance and expression of a character. 
  • F1 generation : It refers to the first filial generation. It consists of all off-springs produced from a parental cross.


  • Genetics: Branch of science which deals with the study of inheritance and variation is known as genetics.
  • Gene : It is a particular segment of DNA which is responsible for the inheritance and expression of that character.

  • Genome: Complete set of DNA or chromosomes of an organisms is known as Genome or Genome is a set of hereditary material (DNA) of an organism.

  • Genomics: Study of genome is k/as genomics.
  • Genotype : Genetic constitution or genetic make up of an organism with respect to a particular trait. 
  • Genetic fingerprinting: detection of variations in the number and length of tandem DNA repeats.
  • Gamete: is a mature sex cell.
  • Genetic map: is a diagram of the location of structural genes and regulatory elements in a chromosome.
  • Genetic code: is the correspondence between the triplets in DNA (or RNA) and the amino acids of proteins.
  • Genetic engineering: is a set of techniques, methods and technologies for obtaining recombinant RNA and DNA, isolating genes from an organism (cells), manipulating genes and introducing them into other organisms.
  • Gene therapy: is the introduction of genetic material (DNA or RNA) into a cell to restore normal function.
  • Glycosylation: is the addition of a carbohydrate residue to a protein.


  • Homozygous (pure) : An individual possessing identical allels for a particular trait, is called homozygous or pure for that trait. 

  • Heterozygous : An individual possessing contrasting alleles for a particular trait, is called heterozygous. 
  • Homologous Chromosomes : The morphologically, genetically and structurally essentially identical chromosomes present in a diploid cell, are called homologous chromosomes.
  • Hereditary disease: is a diseases that can inherited from parents to offspring. 
  • Haploid: is a cell that contains a single set of genes or chromosomes.
  • Haplotype: is a set of conditions/variants of certain loci that are located on the same chromosome, and due to structural features, these conditions are always inherited together.
  • Haplogroup: a set of individuals that have a similar haplotype at certain loci.


  • Inheritance/ Heredity: Transfer of characters from one generation to another generation (Parents to offspring) is known as Inheritance.
  • Interferons: are proteins synthesized by vertebrate cells in response to a viral infection and suppress their development.

  • Intron: is a non-coding region of a gene that is transcribed and then removed from the mRNA precursor during splicing editing.

  • Intron gene: is a gene that contains introns.

  • Immunity: is the mechanism of the body’s fight against infectious agents such as viruses and microbes.

  • Immunotoxin: is a complex between an antibody and a catalytic subunit of a protein poison (diphtheria toxin, ricin, abrin, etc.).

  • Inducer: is a factor (substance, light, heat) that causes the transcription of genes that are in an inactive state.


  • Linkage group: is all genes located on the same chromosome.

  • Ligase: is an enzyme that forms a phosphodiester bond between two polynucleotides.

  • A ligand: is a molecule that is recognized by a specific structure, such as a cell receptor.

  • The leader sequence: is the N-terminal sequence of secreted proteins, which ensures their transport through the membrane and is cleaved off at the same time.

  • Lysis: is the disintegration of a cell caused by the destruction of its membrane.

  • Linker: a short synthetic oligonucleotide used to connect DNA fragments in vitro ; usually contains a recognition site for a specific restriction enzyme.
  • Monohybrid : It is cross between two pure parents differing in single pair of contrasting characters.

  • Mutation: A mutation is a sudden change in the DNA sequence that can be passed down from generation to generation is called mutation. 
  • A marker gene: is a gene in recombinant DNA that encodes a selective trait.
  • Maternal effect genes: are genes that appear in the egg and determine the phenotype of the offspring, regardless of the genotype of the male.
  • Metabolism: is a set of enzymatic processes that ensure the existence and reproduction of the cell.
  • Microsatellite: microsatellite locus (STR – Short Tandem Repeats): a DNA segment with a specific genomic localization containing short tandem repeats.
  • Minicells: are cells that do not contain chromosomal DNA. 
  • Mobile elements of the genome: DNA sequences that can move within the genome of living organisms.
  • Monohybrid cross: crossing forms that differ from each other in one pair of alternative traits.
  • Mutagenesis: is the process of inducing mutations.
  • Mutagens: are physical, chemical or biological agents that causes mutations.
  • Nitrogenase: is an enzyme that fixes atmospheric nitrogen.
  • Nucleases: are the general name for enzymes that break down nucleic acid molecules.
  • Oligonucleotide: is a DNA chain consisting of several (from 2 to 20) nucleotide residues.
  • Oncogenes: are genes whose products have the ability to transform eukaryotic cells so that they acquire the properties of tumor cells.
  • An operator: is a regulatory region of a gene (operon) which regulates the transcription.
  • An operon: is a cluster genes that usually control related biochemical functions.
  • Phenotype : The external apperance of an individual for any trait is called phenotype for that trait.

  • Pure line : An individual or a group of individuals (population) which is homozygous or true breeding for one or more traits, constitutes pure line.
  • Polyploidy: is a multiple of the haploid set of chromosomes in a cell (3n, 4n or more).
  • Polymorphism: is a neutral, or rather harmless, mutation that is relatively common in a group of organisms of the same species.
  • Probe: is a short piece of DNA or RNA of known structure or function, labeled with some kind of radioactive or fluorescent compound.
  • Plasmid: is a circular or linear DNA molecule that replicates independently of the cellular chromosome.
  • A polylinker: is a synthetic oligonucleotide containing recognition sites for several restriction enzymes.
  • Polymerases: are enzymes responsible for the template synthesis of nucleic acids.
  • A polypeptide: is a protein, a polymer consisting of amino acid residues linked by peptide bonds.
  • A primer: is a short oligo- or polynucleotide sequence of DNA or RNA.
  • Prokaryote:s are organisms that do not have a cell nucleus.
  • A promoter: is a regulatory region of a gene (operon) to which RNA polymerase attaches in order to start transcription.
  • Proto- oncogenes: are normal chromosomal genes whose mutations can lead to malignant cell transformation.
  • A protoplast: is a plant or microbial cell lacking a cell wall.
  • Pleiotropy: When a single gene controls two (or more) different traits, it is called pleiotropic gene and the phenomenon is called pleiotropy or pleiotropism.
  • Recessive : This allele is not expressed in the presence of an alternative allele (in heterozygous condition). It expresses only in the presence of another identical allele.
  • Regulation of gene expression:  is the control of cellular structure and function, as well as the basis of cell differentiation, morphogenesis and adaptation.
  • Recombinant DNA molecule: Product obtained by combination of a vector and a foreign DNA fragment.
  • Recombinant protein: a protein obtained by expression from a recombinant DNA molecule, often obtained in Escherichia coli.
  • In vitro recombination: in vitro operations leading to the creation of recombinant DNA molecules.
  • Homologous recombination: is the exchange of genetic material between two homologous DNA molecules.
  • Site-specific recombination: combining by breaking and merging two DNA molecules or sections of one molecule, occurring at certain sites.
  • The recon: unit of the genetic recombination, i.e. area of ​​genetic material within which recombination is possible.
  • Renaturation: is the restoration of the original spatial structure of molecules.
  • DNA repair: is the repair of damage to the DNA molecule, restoring its original structure.
  • A replicator: is a section of DNA responsible for initiating replication.
  • Replication: Formation of exact copy of itself (DNA).
  • A replicon: is a DNA molecule or portion of it that is under the control of a replicator.
  • A repressor: is a protein or antisense RNA that suppresses the activity of genes.
  • Restriction enzymes: are a group of bacterial site-specific endonucleases that recognize certain sections of DNA with a length of four or more base pairs and cleave the nucleotide chain inside or outside the recognition site, forming “sticky” or “blunt” ends.
  • A restriction map: is a diagram of a DNA molecule, which shows the places where it is cut by various restriction enzymes.
  • Ribonucleases (RNases): are enzymes that digest RNA.
  • Selective media: are nutrient media on which only cells with certain properties can grow.
  • Septum: a structure formed in the center of a bacterial cell at the end of the division cycle and dividing it into two daughter cells.
  • Somatic hybrids: are the product of the fusion of non-sex cells.
  • Somatic cells:  are tissue cells of multicellular organisms that are not related to sex.
  • Spacer: in DNA or RNA – a non-coding sequence of nucleotides between genes; in proteins, an amino acid sequence that links adjacent globular domains.
  • Splicing: is the process of forming a mature mRNA or functional protein by removing the internal parts of molecules – RNA introns or inteins from proteins.
  • Superproducer: is a microbial strain aimed at the synthesis of a certain product in high concentration.
  • Sequencing: is a group of methods that allows you to find out the sequence of nucleotides in a DNA molecule. 
  • Trait :An inherited character and its detectable variant e.g. Tall or dwarf.
  • Transduction:  is the transfer of DNA fragments by a bacteriophage.
  • Transcription: Formation of RNA from DNA template and it is carried out by RNA polymerase.
  • A transcript: is a transcription product, i.e., RNA synthesized in a given DNA region as on a template and complementary to one of its strands.
  • Reverse transcriptase: is an enzyme that synthesizes single-stranded DNA complementary to it from RNA as a template.
  • Translation: is the synthesis of a polypeptide chain of proteins from mRNA.
  • A transposon: is a genetic element that replicates as part of a replicon and is capable of independent movement (transposition) and integration into different regions of chromosomal or extrachromosomal DNA.
  • Transfection: is the transformation of cells using isolated DNA.
  • Transformation (in molecular genetics) is the transfer of genetic information through isolated DNA.
  • Veriation: Difference between parents and their offspring.
  • Wild-type (normal): allele is the nucleotide sequence of a gene that ensures its normal operation.

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