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Definitions
List of terms for Genomics
A
Allele
Organisms have two copies of every gene that occupy the same relative position on a specific chromosome. Each alternative form of a gene is called an allele.
Antibody
A protein produced by the immune system in response to an antigen (a molecule that is perceived to be foreign). Antibodies bind specifically to their target antigen to help the immune system destroy the foreign entity. [WHO: Genomics and World Health]
B
Bioinformatics
The assembly of data from genomic analysis into accessible forms. It involves the application of information technology to analyse and manage large data sets resulting from gene sequencing or related techniques. [ICSU: New Genetics, Food and Agriculture]
C
Chromosome
Subcellular structures which convey the genetic material of an organism. [WHO: Genomics and World Health]
Comparative genomics
The comparison of genome structure and function across different species in order to further understanding of biological mechanisms and evolutionary processes. [WHO: Genomics and World Health]
D
Deoxyribonucleic acid (DNA)
The chemical that comprises the genetic material of all cellular organisms. [WHO: Genomics and World Health]
Dominant
The physical characteristics of an organism are determined by a pair of alleles (copies of a gene). An allele is described as dominant if its characteristics are expressed when it is paired with a recessive allele.
F
Functional genomics
The knowledge that converts the molecular information represented by DNA into an understanding of gene functions and effects: how and why genes behave in certain species and under specific conditions. Functional genomics also entails research on the protein function (proteomics) or, even more broadly, the whole metabolism (metabolomics) of an organism. [ICSU: New Genetics, Food and Agriculture]
G
Gene
The fundamental unit of heredity. In molecular terms, a gene comprises a length of DNA that encodes a functional product, which may be a polypeptide (a whole or constituent part of a protein) or a ribonucleic acid. [WHO: Genomics and World Health]
Gene therapy
The introduction of genetic material into an individual, or the modification of the individual’s genetic material, in order to achieve a therapeutic objective. [WHO: Genomics and World Health]
Genetic Susceptibility
Predisposition to a particular disease or disorder due to the presence of a particular allele or combination of alleles in an individual's genome. [WHO: Genomics and World Health]
Genome
The sum total of the genetic material present in a particular organism. A genome is all of a living thing's genetic material. It is the entire set of hereditary instructions for building, running and maintaining an organism, and passing life on to the next generation. In most living things, the genome is made of a chemical called DNA. [ICSU: New Genetics, Food and Agriculture]
Genotype
The total genetic constitution of an organism. [WHO: Genomics and World Health]
H
Human Genome Project
A programme to determine the sequence of the entire three billion (3x109) bases of the human genome. [WHO: Genomics and World Health] (NB Note superscript on exponential)
M
Marker
A specific feature at an identified physical location on a chromosome, whose inheritance can be followed. The position of a gene implicated in a particular phenotypic effect can be defined through its linkage to such markers. [WHO: Genomics and World Health]
Microarray
A grid of nucleic acid molecules of known composition linked to a solid substrate, which can be probed to reveal changes in gene expression relative to a control sample. Microarray technology, which is also known as “DNA chip” technology, allows the expression of many thousands of genes to be assessed in a single experiment. [WHO: Genomics and World Health]
Multifactorial (multigenic) disease
A disease whose pathology is dependent on the complex interplay of several genetic and environmental factors. [WHO: Genomics and World Health]
Mutation
A structural change in a DNA sequence resulting from uncorrected errors during DNA replication. [WHO: Genomics and World Health]
P
Phenotype
The observable characteristics of an organism. [WHO: Genomics and World Health]
R
Recessive
The physical characteristics of an organism are determined by a pair of alleles (copies of a gene). An allele is described as recessive if its characteristics are only expressed when it is paired with an identical allele, and not when it is paired with the dominant allele.
Recombinant DNA technology
The term given to some techniques of molecular biology and genetic engineering which were developed in the early 1970s. In particular, the use of restriction enzymes, which cleave DNA at specific sites, allow sections of DNA molecules to be inserted into plasmid or other vectors and cloned in an appropriate host organism (e.g. a bacterial or yeast cell). [WHO: Genomics and World Health]
Reproductive cloning
Techniques aimed at the generation of an organism with an identical genome to an existing organism. [WHO: Genomics and World Health]
Ribonucleic acid (RNA)
A single stranded nucleic acid molecule comprising a linear chain made up from four nucleotide subunits (A, C, G and U). There are three types of RNA: messenger, transfer and ribosomal. [WHO: Genomics and World Health]
S
Shotgun sequencing
A cloning method in which total genomic DNA is randomly sheared and the fragments subsequently cloned. [ICSU: New Genetics, Food and Agriculture]
Single nucleotide polymorphism (SNP)
This is the most common type of genetic variation. SNPs are stable mutations consisting of a change at a single base in a DNA molecule. [ICSU: New Genetics, Food and Agriculture]
T
Therapeutic cloning
The generation and manipulation of stem cells with the objective of deriving cells of a particular organ or tissue to treat a disease. [WHO: Genomics and World Health]
Transgenic animal/plant
A fertile animal or plant that carries an introduced gene(s) in its germ-line. [WHO: Genomics and World Health]
