Glossary

This glossary was produced by the Canadian Museum of Nature, in collaboration with Genome Canada and its partners. The definitions were prepared using various sources; in the interest of transparency, these have been included with the definitions.

You wish to add more words to the glossary? Send your request by e-mail to gqinfo@genomequebec.com


A

A, T, C, G

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

Adenine

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

Allele

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.

Amniocentesis

A prenatal test in which a hollow needle is inserted into the uterus to obtain some of the fluid surrounding a foetus (baby). The cells are examined to determine the sex of the baby, or to find abnormalities in the chromosomes.

Antibody

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.

Autosome

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

B

Bacteria

Unicellular organisms whose structure has no nucleus (characterized by the absence of a nucleus and organelles).
Sources: 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.

Biodiversity

The biological variety in an environment as indicated by numbers of different species of plants and animals.

Source: Word Central's Student Dictionary

Bioremediation

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 additional information, please click here.

Biotechnology

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

BRCA1/BRCA2

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.

C

Cancer

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. 

Carrier

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

Cell

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.

Chlorophyll

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

Chloroplasts

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

Chromosome

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.

Clone

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

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.

Codon

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

Conception

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

Cytoplasm

The viscous semi-liquid inside the membrane of a cell.

Cytosine

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.

D

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.

Disorders

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

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

DNA

Short for deoxyribonucleic acid.

DNA fingerprinting

In genetics, the identification of multiple specific alleles on a person's DNA to produce a unique identifier for that person. Also called genetic test.

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.

E

Electrophoresis

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.

Embryo

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.

Enzyme

A protein that encourages a biochemical reaction, usually speeding it up. Organisms could not function if they didn't have enzymes.

Epigenetics

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

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.

Eukaryote

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

Evolution

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.

G

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.

Genes

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 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

Genetics

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

Genome

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.

Genomics

The study of the entire set of genes found in living things (humans, plants, animals or viruses); the analysis of the genomes of organisms, both anatomically (sequences and organization) and physiologically (expression and regulation). For more information, please click here.

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.

Guanine

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.

H

Haplotype

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

Heridity

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

Source: Human Genome Project Information

High-throughput sequencing

The high demand for low-cost sequencing has driven the development of high-throughput sequencing technologies that parallelize the sequencing process, producing thousands or millions of sequences at once. High-throughput sequencing technologies are intended to lower the cost of DNA sequencing beyond what is possible with standard dye-terminator methods. In ultra-high-throughput sequencing as many as 500,000 sequencing-by-synthesis operations may be run in parallel.

Source: Wikipedia

Histones

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

Hormones

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

Source: Human Genome Project Information

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.

I

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

Immunotherapy

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.

Inherited

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.

K

Karyotype

The chromosomal complement of an individual, including the number of chromosomes and any abnormalities. The term is also used to refer to a photograph of an individual's chromosomes.

Knockout

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.

L

Leukemia

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.

Lysosome

Organelles enclosed in membranes, containing digestive enzymes.

M

Meiosis

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

Microbiome

A microbiome is the totality of microbes, their genetic elements (genomes), and environmental interactions in a particular environment. Microbiomes are being characterized in many other environments as well, including soil, seawater and freshwater systems.

Source: Wikipedia

Microbiota

The microscopic flora and fauna of a region.

source : www.btb.termiumplus.gc.ca

Mitochondrial DNA

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

Mitosis

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

Molecule

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

Mutagenesis

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

Source: Human Genome Project Information

Mutation

A permanent structural alteration in DNA. In most cases, DNA changes either have no effect or cause harm, but occasionally a mutation can improve an organism's chance of surviving and passing the beneficial change on to its descendants.

N

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.

Nucleus

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.

O

Oncogene

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

Organism

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

P

Personalized medicine

Involves the use of new methods of genomic analysis to better manage a patient’s disease or predisposition to it. It aims to achieve optimal medical outcomes by helping physicians and patients choose the therapeutic option most likely to work, given the patient’s unique genetic and environmental profiles. For more information, click here.

Pharmacogenetics

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

Phenotype

The observable traits or characteristics of an organism (e.g., hair colour, weight) or the presence or absence of a disease. Phenotypic traits are not necessarily genetic.

Photosynthesis

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

Plasmids

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

Polynucleic

Having more than one nucleus.

Prokaryote

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

Source: Human Genome Project Information

Protein

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

Proteomics

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

Source: Human Genome Project Information

R

Recessive

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.

Recombination

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

Replication

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.

Ribosome

A cellular organelle that is the site of protein synthesis.

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.

S

Sequencing

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)

A DNA sequence variation occurring when a single nucleotide — A, T, C or G — in the genome (or other shared sequence) differs between members of a biological species or paired chromosomes in an individual.

Source: Wikipedia

Species

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.

T

Thymine

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.

Traits

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

Source: Human Genome Project Information

Transcription

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

Source: PhRMA Genomics

Transfer RNA (tRNA)

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

Source: PhRMA Genomics

Transgenic

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.

Translation

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

Source: PhRMA Genomics

U

Ultrasound imaging

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

Source: Human Genome Project Information

Uracil

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.

V

Vector

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.

Virus

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

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