A, T, C, G

Symbols for the bases adenine, thymine, cytosine and guanine.


One of the four bases in DNA that make up the letters A, T, C, G. Adenine is the "A". The others are cytosine, thymine, and guanine. Adenine always pairs with thymine.

Adenosine triphosphate (ATP)

A compound that occurs widely in living tissue and serves as a major source of energy.
Source: Word Central's Student Dictionary


Alternate forms of a gene at a particular location on a chromosome. Different alleles produce variation in inherited traits such as hair colour or blood type.
Source: National Human Genome Research Institute

Amino acid

Different kinds of small molecules that link together in long chains to form proteins; amino acids are often referred to as the "building blocks" of proteins.


Sampling of the fluid that surrounds the fetus.

Analytical Validity


Abnormal number of chromosomes, either extra or missing.


Antibodies help the body develop immunity to disease. Blood proteins are produced in response to a disease and help the body fight against that particular disease.


Any chromosome other than a sex chromosome; humans have 22 pairs of autosomes.



Unicellular organisms whose structure has no nucleus (characterized by the absence of a nucleus and organelles).
Source: Wikipedia, National Human Genome Research Institute

Base (or nucleotide)

One of the structural components, or building blocks, of DNA and RNA. A nucleotide consists of a base (one of four chemicals: adenine, thymine, guanine, and cytosine) plus a molecule of sugar and one of phosphoric acid.
Source: National Human Genome Research Institute


Base pair

Two bases which form a "rung of the DNA ladder". A DNA nucleotide is made of a molecule of sugar, a molecule of phosphoric acid, and a molecule called a base. The bases are the "letters" that spell out the genetic code. In DNA, the code letters are A, T, C, and G, which stand respectively for the chemicals adenine, thymine, cytosine, and guanine. In base pairing, adenine always pairs with thymine, and guanine, with cytosine.


The biological variety in an environment as indicated by numbers of different species of plants and animals.
Source: Word Central's Student Dictionary

Bioinformatics (see computational biology)

Computational biology (also called bioinformatics) integrates biological themes together with the help of computer tools and biological databases, in order to gain new knowledge about the system in study. 


A range of methods used to clean up polluted soil, water, and air, through the careful combination of various factors; it generally involves interaction among plants, the soil and microorganisms (bacteria and fungi).
For more information about bioremediation, click here.


The application of biological science, especially the use of genetic techniques, to combine DNA from different sources into one organism in order to produce useful products (as drugs).
Source: Word Central's Student Dictionary


The first breast cancer genes to be identified. Mutated forms of these genes are believed to be responsible for about half the cases of inherited breast cancer, especially those that occur in younger women. Both are tumour suppressor genes.



Disease(s) in which abnormal cells divide and grow unchecked. Cancer can spread from its original site to other parts of the body and can also be fatal if not treated adequately. 


A person who has one copy of the gene mutation for a recessive disorder is called a "carrier". Carriers are not affected by the disorder; however, they can pass on the mutated gene to their children. Children who inherit two such genes may be affected by the disorder.

Source: Human Genome Project Information


The basic unit of any living organism; a cell is a small, watery, compartment filled with chemicals and a complete copy of the organism's genome.


The green colouring matter of plants that is found in chloroplasts and is necessary to make plant food from carbon dioxide and water by photosynthesis.

Source: Word Central's Student Dictionary


An area in a plant cell that contains chlorophyll and is the location of photosynthesis and starch formation.


A complex of macromolecules found in cells, consisting of DNA, protein and RNA. The primary functions of chromatin are 1) to package DNA into a smaller volume to fit in the cell, 2) to reinforce the DNA macromolecule to allow mitosis, 3) to prevent DNA damage, and 4) to control gene expression and DNA replication.


One of the threadlike "packages" of genes and other DNA in the nucleus of a cell. Different kinds of organisms have different numbers of chromosomes. Humans have 23 pairs of chromosomes - so 46 in all - 44 autosomes and two sex chromosomes. Each parent contributes one chromosome to each pair, so children get half of their chromosomes from their mother and half from their father.

Clinical Benefit

Using clinical tests considerably improves health outcomes for patients compared to not using them.


Clinical Validity

A measure of how accurate a test is in identifying or predicting a clinical disorder.



An exact copy of biological material such as a DNA segment (e.g., a gene or other region), a whole cell, or a complete organism.

Source: Human Genome Project Information


Cloning creates a genetically identical copy of an animal or plant. Cloning is the process of making copies of a specific piece of DNA, usually a gene. When geneticists speak of cloning, they do not mean the process of making genetically identical copies of an entire organism.


Three bases in a DNA or RNA sequence, which specify a single amino acid.

Computational biology

Bioinformatics (also known as Computational biology) integrates biological themes together with the help of computer tools and biological databases in order to gain new knowledge about the system in study. 


In reproduction, conception is the point at which a sperm fertilizes an egg.


A jelly-like fluid that fills each cell.


One of the four bases in DNA that make up the letters A, T, C, G. Cytosine is the "C". The others are adenine, thymine, and guanine. Cytosine always pairs with guanine.


Deoxyribonucleic acid (DNA)

DNA is the chemical inside the nucleus of a cell that carries the genetic instructions for making living organisms. A long molecule, and usually packaged into chromosomes, DNA encodes genetic information in the form of a double helix held together by bonds between base pairs.


Problems in how the body functions. Health problems caused by mutations in the genes are referred to as genetic disorders.

Source: Human Genome Project Information


Diversity describes the different types of organisms that exist within a community or ecological system.


Short for deoxyribonucleic acid.

DNA Fingerprinting

A genetic test to identify multiple specific alleles on a person’s DNA used to produce a unique identifier (or “fingerprint”) for that person. 

Source: Human Genome Project Information

DNA polymerase

The enzyme in DNA replication that links the complementary nucleotide bases together to make the newly synthesized strand.
Source: Cellupedia

DNA replication

The process by which the DNA double helix unwinds and makes an exact copy of itself.

Dominant gene

A gene that almost always results in a specific physical characteristic, for example, a disease, even though the patient's genome possesses only one copy. With a dominant gene, the chance of passing on the gene (and therefore the disease) to children is 50-50 in each pregnancy.

Double helix

The structural arrangement of DNA, which looks something like an immensely long ladder twisted into a helix or coil. The sides of the "ladder" are formed by a backbone of sugar and phosphate molecules, and the "rungs" consist of nucleotide bases joined weakly in the middle by hydrogen bonds.



The process in which molecules (such as proteins, DNA, or RNA fragments) can be separated according to size and electrical charge by applying an electric current to them. The current forces the molecules through pores in a thin layer of gel, a firm jelly-like substance. The gel can be made so that its pores are just the right dimensions for separating molecules within a specific range of sizes and shapes. Smaller fragments usually travel further than large ones. The process is sometimes called gel electrophoresis.


An animal in the early stage of development before birth (in humans, the embryo stage is the first three months following conception). 

Source: Human Genome Project Information

Endoplasmic reticulum (ER)

A network of membranous tubules in the cytoplasm of a cell, endoplasmic reticulum is involved in the production of proteins, and other functions. Rough ER is studded with ribosomes; smooth ER is not.


A protein that catalyzes a chemical reaction, usually speeding it up.  Organisms could not function without enzymes.


In biology, and specifically genetics, epigenetics is the study of heritable changes in gene expression or cellular phenotype caused by mechanisms other than changes in the underlying DNA sequence. It refers to functionally relevant modifications to the genome that do not involve a change in the nucleotide sequence.

Source: Wikipedia


Epigenomics is the study of the complete set of epigenetic modifications on the genetic material of a cell, known as the epigenome. The field is analogous to genomics and proteomics, which are the study of the genome and proteome of a cell. Epigenetic modifications are reversible modifications on a cell’s DNA or histones that affect gene expression without altering the DNA sequence.

Source: Wikipedia

Ethical issues

Questions that concern what is moral or right.


A cell or organism with membrane-bound, structurally discrete nucleus and other well-developed subcellular compartments. Eukaryotes include all organisms except viruses, bacteria, and blue-green algae.

Source: Human Genome Project Information


The process by which all forms of plant and animal life change slowly over time because of slight variations in the genes that one generation passes down to the next.


Part of the genome of a eukaryotic organism formed by exons, the coding region of genes that contain information to encode proteins.


Gene therapy

An evolving technique used to treat inherited diseases. The medical procedure involves replacing, manipulating, or supplementing non-functional genes with healthy genes, in order to affect their function.


The functional and physical units of heredity passed from parent to offspring, genes are pieces of DNA stored in the cell nucleus. They are the recipes for making proteins. Each gene consists of several thousand code words. Each person’s cells contain the same unique and complete set of genes.

Genetic code (ATCG)

The instructions in a gene that tell the cell how to make a specific protein, A, T, C and G are the "letters" of the DNA code. They stand for the chemicals: adenine, thymine, cytosine, and guanine, respectively, that make up the nucleotide bases of DNA. Each gene's code combines the four chemicals in various ways to spell out 3-letter "words" that specify which amino acid is needed at every step in making a protein.

Genetic Counselling

The process of genetic counselling consists of helping patients and their families understand and adapt to the medical and psychological implications of the genetic aspects of disease.


Genetic engineering

The artificial introduction of changes to the genes in a cell.

Source: Human Genome Project Information

Genetic profile

A collection of information about a person's genes.

Source: Human Genome Project Information

Genetic test

Examination of a sample of blood or other body fluid or tissue for biochemical, chromosomal or genetic markers that indicate the presence or absence of a genetic disease.  

Genetically modified organism (GMO)

An organism whose genetic make-up has been changed by any method, including natural processes, genetic engineering, cloning or mutagenesis.

Source: Human Genome Project Information


The field of science that looks at how traits are passed down from one generation to another, through the genes.

Source: Human Genome Project Information


The complete package of genetic material for a living thing, a genome is one copy of the entire DNA in a cell of an organism (animal, plant or microbe) and includes both the chromosomes within the nucleus and the DNA in mitochondria. A copy of the genome is found in most cells. Our genome is 3,400,000,000 base pairs, packaged into 23 pairs of chromosomes: bacteria may have only 1,500,000 base pairs in one chromosome.


The study of the entire set of genes found in living beings (humans, plants, animals or viruses); the analysis of the genomes of organisms, both anatomically (sequences and organization) and physiologically (expression and regulation).

These detailed studies are conducted using high-throughput methods and strategies involving the full set of genes. By extension, genomics also refers to the use of these methods to conduct the detailed study of large regions of the genome, such as the exome (the set of the coding parts of all genes) or a combination of several dozens (even hundreds) of genes at once. Genomics does not include simple genetic tests such as screening for known mutations in a small number of regions of the genome or the sequencing of small regions of the genome.
To learn more about genomics, click here.


The whole or part of the genetic constitution of an individual. In other words, it refers to the allelic composition of the entire set of genes of an individual.

Germ cells

The cells of the body involved in reproduction. Sperm of the male and eggs of the female are formed from germ cells.
Source: Human Genome Project Information

Golgi complex (Golgi apparatus)

The Golgi complex refers to organelles in animal cells made up of a series of sacs that sort, modify, and package proteins produced on the rough endoplasmic reticulum.


One of the four bases in DNA that make up the letters ATCG, guanine is the "G". The others are adenine, cytosine, and thymine. Guanine always pairs with cytosine.



A combination of alleles at adjacent locations on the chromosome that are normally transmitted together. The term is used in immunology to indicate a set of connected genes located on the same chromosome and coding diverse blood antigens or tissular.
Source: Wikipedia


The passing of certain traits from parents to their offspring. The process of heredity occurs through the genes.

Source: Human Genome Project Information


Highly alkaline proteins found in eukaryotic cell nuclei; they are the major proteic constituents of the chromosomes. Histones play a role of non-specific repression in the transmission of the genetic message.

Source: Wikipedia


Proteins produced by organs of the body that trigger activity in other locations.

Source: Human Genome Project Information

Human Genome

The complete package of genetic material of an organism. Genetic material is all of a living being’s genetic information found in a cell which it needs to function. It includes both coding sequences, which encode proteins, and non-coding sequences. In the majority of organisms, the genome corresponds to the DNA contained in each cell. Human being have approximately 23,000 genes.

Human Genome Project

An international research project to map each human gene and to completely sequence human DNA. The project began in 1990. Its completion was announced in 2003.


Immune system

A biological defence system that has evolved in vertebrates to protect them against the introduction of foreign material (such as pollen, or invading micro-organisms) and to prevent the body from developing cancer.

Source: PhRMA Genomics


The concept of using the immune system to treat disease. For example, using the immune system to develop a vaccine against cancer. Immunotherapy may also refer to therapy for diseases caused by the immune system, allergies for example.


Transmitted through genes from parents to offspring.

International HapMap Project

An international research project to identify and catalogue genetic similarities and differences in human beings. The goal is to compare the genetic sequences of different individuals to identify chromosomal regions where genetic variants are shared. By using this information, researchers will be able to find genes that affect health, disease, and individual responses to medications and environmental factors.


Introns, as opposed to extrons, are generally the non-coding part of a gene. Introns are eliminated from RNA to make way for mature RNA. Introns are believed to enable the coding of many proteins at the same time, helping cells conserve energy.



The standard arrangement of chromosomes in a cell, including the number of chromosomes and any anomalies. The term is also used to refer to a photograph of the chromosomes of a cell.

Source: Wikipedia


Inactivation of specific genes, knockouts are often created in laboratory organisms (such as yeast or mice) so that scientists can study the knockout organism as a model for a particular disease.



Cancer of the developing blood cells in the bone marrow. Leukemia leads to rampant overproduction of white blood cells (leukocytes); symptoms usually include anaemia, fever, and enlarged liver, spleen, and/or lymph nodes.


Organelles enclosed in membranes, containing digestive enzymes.



The process of two consecutive cell divisions in the diploid progenitors of sex cells. Meiosis results in four rather than two daughter cells, each with a haploid set of chromosomes.

Source: Human Genome Project Information

Messenger RNA (MRNA)

"Blueprint" for protein synthesis that is transcribed from one strand of the DNA (gene) and which is translated at the ribosome into a polypeptide sequence. Each set of three bases, called codons, specifies a certain protein in the sequence of amino acids that comprise the protein. The sequence of a strand of mRNA is based on the sequence of a complementary strand of DNA.
Source: Wikipedia


The complete set of chemical reactions that happen in an organism. Includes the conversion of food into energy, production of components for new cells and maintenance of existing cells.


Any chemical compound involved in or a product of metabolism.


The study of the set of metabolites present within an organism, cell or tissue.


The totality of micro-organsims and their genomes present in a living animal. These micro-organisms maintain a relationship of commensalism with the living animal, where they play a very important role in digestion, protection against pathogens and more. Their populations form an ecosystem, which we know very little about at this point, and are now under study. These micro-organisms can be sequenced through metagenomics, which refers to the study of a complete ecosystem.


The microscopic flora and fauna of a region.

Source :


Mitochondrial DNA

The genetic material of the mitochondria, the organelles that generate energy for the cell.


The process of nuclear division in cells that produces daughter cells, that are genetically identical to each other and to the parent cell.

Source: Human Genome Project Information


The smallest particle of a substance having all the characteristics of the substance.

Source: Word Central Student's Dictionary

Monogenic disorder

A disorder which is caused by mutations in just one gene (such as haemophilia), as opposed to polygenic disorders (such as hypertension) which involve the interaction of several genes.

Source: PhRMA Genomics


When a chemical or physical agent is used to cause permanent genetic alterations.

Source: Human Genome Project Information


A rare, accidental or intentional change of the genetic information (DNA or RNA sequence) of a genome. While every human being is unique, from a genetic standpoint, there is only 0.1% difference among the genomes of every person. The consequences of a mutation can vary depending on the part of the genome affected. The term “mutation” refers to any change in the DNA sequence, regardless of its pathogenecity on a gene or chromosome. There are also “variants.” A mutation is said to be hereditary if the mutated sequence is passed down to the next generation. But DNA variations (knowns as “polymorphisms”) are also, by definition, mutations.


Next Generation Sequencing

Next generation sequencing (NGS), also known as high-throughput sequencing, is a term commonly used to describe various modern sequencing techniques. These recent technologies are used to sequence DNA and RNA more rapidly than previous methods, such as Sanger sequencing, and, as a result, have revolutionized the study of genomics and molecular biology.

Source :

Nuchal translucency test

The nuchal translucency test is used to determine if a woman is at high risk of having a baby with a chromosomal abnormality, such as Down Syndrome.

Nucleotide (or base)

One of the structural components, or building blocks, of DNA and RNA. A nucleotide consists of a base (one of four chemicals: adenine, thymine, guanine, and cytosine) plus a molecule of sugar and one of phosphoric acid.


The largest, most prominent organelle in eukaryotic cells, the nucleus is a round or oval body that is surrounded by the nuclear envelope and contains the genetic information necessary for control of cell structure and function. It is the central cell structure that houses the chromosomes and is essential to such cell functions as growth, metabolism, and reproduction.



A gene that is capable of causing the transformation of normal cells into cancer cells.


The specialty branch of medicine that deals with cancerous tumours. It is also known as cancerology.


An individual living thing that carries on the activities of life by means of organs which have separate functions but are dependent on each other: a living person, plant, or animal.

Source: Word Central Student's Dictionary



The science of understanding the correlation between an individual patient's genetic make-up (genotype) and their response to drug treatment. Some drugs work well in some patient populations and not as well in others. Studying the genetic basis of patient response to therapeutics allows drug developers to more effectively design therapeutic treatments.

Source: Human Genome Project Information


The set of observable characteristics of an individual (hair colour, eye colour, shape of the ears or nose, etc.) or of the individual’s cells. The phenotype is the result of the genotype (the expression of genes), but also of the effect of the individual’s environment.


The process by which plant cells convert light from the sun into adenosine triphosphate (ATP), a source of energy for the cell.


A structure composed of DNA that is separate from the cell's genome. In bacteria, plasmids confer a variety of traits and can be exchanged between individuals - even those of different species. Plasmids can be manipulated in the laboratory to deliver specific genetic sequences into a cell.

Source: PhRMA Genomics


Having more than one nucleus.

Precision Medicine and Personalized Medicine

While precision medicine and personalized medicine are often used interchangeably, they differ slightly on a few points. Precision medicine is used for stratification at the molecular level, while personalized medicine aims to identify specific therapies and/or target prevention and treatment strategies based on an individual’s unique characteristics (for example, sociocultural).


Cell or organism lacking a membrane-bound, structurally discrete nucleus and other subcellular compartments. Bacteria are examples of prokaryotes.

Source: Human Genome Project Information


A large complex molecule made up of one or more chains of amino acids. Proteins perform a wide variety of activities in the cell.


The entire set of proteins expressed by a cell, part of a cell (membrane, organels) or group of cells (organ, organism, group of organisms) in giving conditions at a given time. The study of the proteome, proteomics, leads to a better understanding of cell function based on the overall expression of proteins.


The study of the full set of proteins encoded by a genome.

Source: Human Genome Project Information



A genetic disorder that appears only in individuals that have received two copies of a mutant gene, one from each parent.

Recombinant DNA

A variety of techniques that molecular biologists use to manipulate DNA molecules to study the expression of a gene.


Recombinant DNA is produced when genetic information from more than one organism is recombined in a laboratory process into a hybrid molecule.

Source: PhRMA Genomics


[When referring to a condition or disease] means the said condition or disease is not responding favourably to treatment.


The process by which DNA is duplicated before cell division.

Ribonucleic acid (RNA)

A chemical similar to a single strand of DNA. In RNA, the letter U, which stands for uracil, is substituted for T in the genetic code. RNA delivers DNA's genetic message to the cytoplasm of a cell where proteins are made.


A cellular organelle that is the site of protein synthesis.

RNA Interference

RNA interference (RNAi) is an evolutionally conserved mechanism that has been shown to play an essential role in the regulation of gene expression. The discovery of this phenomenon has generated much interest and hopes for functional genomics and human therapeutics.

RNA polymerase

An enzyme that, during transcription, attaches to the promoter region of the DNA template, joins nucleotides to form the synthesized strand of RNA, and detaches from the template when it reaches the terminator region.



In medicine, screening involves looking for one more disease or anomalies in “at-risk” individuals of a given population.


In genetics and biochemistry, sequencing means determining the primary structure (sometimes falsely called primary sequence) of an unbranched biopolymer. Sequencing results in a symbolic linear depiction known as a sequence which succinctly summarizes much of the atomic-level structure of the sequenced molecule. DNA sequencing is the process of determining the nucleotide order of a given DNA fragment.

Source: Wikipedia

Sex chromosome

A sex chromosome is one of the two chromosomes that specify an organism's genetic sex. Humans have two kinds of sex chromosomes, one called X and the other Y. Normal females possess two X-chromosomes and normal males one X and one Y.

SNP (Single Nucleotide Polymorphism)

Most common forms of mutations involving a change in the nucleotide anywhere in the genome. To be considered an SNP, the change needs to be present in more than 1% of the population.


A single, distinct class of living creature with features that distinguish it from others.

Stem cell

A stem cell is an undifferentiated cell characterized by its capacity to generate specialized cells by differentiation, and its ability to multiply itself almost indefinitely.



One of the four bases in DNA that make up the letters ATCG, thymine is the "T.” The others are adenine, cytosine, and guanine. Thymine always pairs with adenine.


Ways of looking, thinking, or being. Genetic traits are passed down through the genes from parents to offspring.

Source: Human Genome Project Information


The process during which the information in a strand of DNA is used to construct an mRNA molecule.

Source: PhRMA Genomics


The sum total of all messenger RNA resulting from the expression of a portion of the genome, in other words, the genes expressed.


The study of all RNA messengers (mRNA) produced during a genome’s transcription process. It uses the systematic quantification of mRNAs, which helps to obtain a relative indication regarding the transcription rate of different genes in given conditions.

Transfer RNA (tRNA)

RNA molecules which bond with amino acids and transfer them to ribosomes, where protein synthesis is completed.
Source: PhRMA Genomics


An experimentally produced organism in which DNA has been artificially introduced and incorporated into the organism's germ line, usually by injecting the foreign DNA into the nucleus of a fertilized embryo.


The process during which the information in mRNA molecules is used to construct proteins.

Source: PhRMA Genomics


Ultrasound imaging

A technique for looking inside the body by using sound waves to create images.

Source: Human Genome Project Information


Uracil is one of the four bases in RNA. The others are adenine, cytosine, and guanine. Uracil replaces thymine, which is the fourth base in DNA. Like thymine, uracil always pairs with adenine.



An agent, such as a virus or a small piece of DNA called a plasmid that carries a modified or foreign gene. When used in gene therapy, a vector delivers the desired gene to a target cell.


Extremely small and simple life forms made merely of a protein shell and a genome. A virus reproduces by inserting its genome into the cells of other life forms. As those cells duplicate, so does the virus.

Source: Human Genome Project Information