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Glossary |
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Blastocyst: embryo
development stage characterized by the formation of a cavity inside
the morula (set of embryonic cells): the blastocœlium. ES
cells can be injected in blastocysts to create chimeras
or transgenic animals
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Cartography or
genetic mapping: set of technologies used to establish the localization
of the genes in the chromosomes
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Chimera: organism
that contains cells or tissues with different genotypes
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Deletion:
excision of a DNA fragment, as opposed to insertion;
mutation occurring naturally, but also artificially by using a molecular
biological strategy
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DNA: Deoxyribonucleic
acid; Molecule that encodes genetic information; main component
of the chromosomes; DNA is a double-stranded helix held together
by bonds between pairs of nucleotides.
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DNA sequencing:
method for deciphering the relative order of nucleotide bases
in a DNA molecule
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ES cells: Embryonic
stem cells. Cultured cells derived from the pluripotent inner cell
mass of blastocyst stage embryos. Used for gene targeting
by homologous recombination
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Fertilized mouse egg:
embryo at “ one cell ” stage
of development
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Gene: DNA
sequence encoding one particular protein
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Genetic code: used
by the cells to translate genetic information in a protein
sequence; three successive nucleotides in a gene form
one codon, and each codon calls for a single amino acid. For example,
the set AUG (adenine, uracil, guanine) calls for the amino acid
methionine. The sequence of codons along a gene specifies the sequence
of amino acids in a particular protein. Instructions appearing
in the genes are converted (transcription) in RNA,
and then translated (translation) in protein
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Gene expression:
mechanism by which gene information is used to
create one protein
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Gene product:
protein encoded by a gene
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Gene targeting:
molecular biological strategy that allows a point intervention in
the genome, at the level of a clearly delimited sequence, as opposed
to classical transgenesis
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Genome: genetic
heritage from an individual or species; the set of genes
that ensures transmission of hereditary characteristics
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Genomic: study
of genes and their functions
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Genotype: genetic
profile indicating the particular characteristics of the genome
of an organism
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Germ cells:
sperm and egg cells, and their precursors. Germ cells are haploid
(only
one set of chromosomes, while the other somatic cells have two copies) and transmit the genetic characteristics to the lineage |
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Homologous recombination:
exchange of genetic material between two DNA
fragments presenting sequence homologies
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Inducible: transcription
of some genes can be triggered by inducers, small molecules
able to act on regulating sequences of these genes
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Insertion:
genetic mutation by introduction of one or more nucleotides
in a DNA sequence
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Knock-in: describes
a mouse in which one particular gene sequence has been replaced
by another
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Knock-out:
describes a mouse in which one particular gene sequence has
been modified to block gene expression
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Micro-injection:
technology used in the laboratory to introduce a transgene
into fertilized mouse eggs
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Mutation: change
in nucleotide sequence of DNA
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Nuclear transfer: technology
where a nucleus from one cell is transferred into an enucleated
cell (most of the time an embryo).
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Nucleotide:
elementary component of nucleic acids (DNA or RNA),
consisting of a nitrogenous base, purine (adenine A; guanine G)
or pyrimidine (cytosine C; thymine T in DNA, or uracil U
in RNA), associated with phosphate and a sugar molecule (deoxyribose
in DNA and ribose in RNA)
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Predictability: property
of a research system (e.g., an animal model) to mimic human physiology.
A model of high predictability provides researchers with results that
are closer to those they would obtain directly if they could perform
the experiments in humans.
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Protein: molecule
composed of amino acids; for each protein, the order of the amino
acids is related to the chain of the codons (groups of three nucleotides)
from the gene encoding this protein; obtained by the translation
mechanism; see also genetic code
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Promoter: DNA
sequence regulating gene expression; the nature of the promoter
determines which transcription effectors will stimulate or
repress the gene. The promoters can be functional in a tissue-specific
manner, or activated in particular biological conditions
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RNA: Ribonucleic
acid; molecule similar to DNA and implicated in cellular
mechanisms of genetic information deciphering; obtained by the transcription
process
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Somatic cells: somatic
line includes all the body cells except germ cells. NB: gene
therapy in humans concerns only somatic cells
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Translation: cellular
process by which protein synthesis from RNA is achieved
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Transcription:
cellular process by which DNA is converted to RNA
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Transgene: gene
artificially introduced into the cell or into the genome of an individual
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Transgenic:
organism (mouse) whose genome has been altered by the inclusion
of foreign genetic material
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Vector:
tool (particular DNA sequence) permitting the transport of
foreign or modified DNA
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- © genOway 2003 -
A provider in Transgenesis: knock out mouse, knock-in mouse and transgenic mouse