Research & Genetics>Genetic Terms
Glossary of Genetic Terms:
Alleles– One of two or more alternative versions of the same gene.
Amino acids – One of the chemical compounds that are the building blocks of proteins.
Autosomes – The name given to all chromosomes other than the two involved in determining the sex of an individual (the X and Y chromosomes). The dog has 38 pairs of
autosomes and one pair of sex chromosomes.
Bases - There are four bases which join together to form DNA, Adenine, Guanine, Thymine and Cytosine, identified by their initials A, G, T and C. The bases join end to end to give a molecule of DNA. These bases join in a specific sequence and it is this base sequence that represents the genetic plan.
Candidate gene – A gene involved in a particular inherited disease in the dog which has been identified because the same gene is known to be the cause of a similar
disease in man or other animals.
Carrier – With regard to hereditary disease this is a dog that carries a recessive, mutant allele that is matched by the presence of a normal allele. On average, it
will pass on this mutant allele to half of its offspring.
Cells – One of the tiny living units from which organisms are made.
Cell membrane – The thin protective membrane that surrounds a cell.
Characteristic – A feature such as brown or blue eyes.
Chromosome – This is the body that carries the DNA within the nucleus. A thread of DNA runs along the length of each chromosome carrying individual genes.
Code – Cells use the genetic code to convert the DNA’s sequence of bases into a sequence of amino acids.
Congenital – Present at birth. May be inherited, but not necessarily.
Cytoplasm – The thick fluid that forms most of the inside of a cell.
DNA (Deoxyribonucleic Acid) – The chemical found in the nucleus of a cell that makes up chromosomes and genes. DNA consists of two chemical strands which twist around each other in the form of a helix. Each strand is made up by the joining together of the chemical units called bases.
DNA Sample – DNA can be collected in a number of ways. The most common methods used with dogs are by blood sample or a scraping of cheek cells, this is called a buccal sample.
Dominant Mutation – A mutation that can express itself when present only as a single copy, even in the presence of a normal allele.
Enzyme – A type of protein found in the body that greatly speeds up the rate of chemical reactions inside and outside cells.
Gamete – A reproductive cell. At fertilisation, the male gamete (the sperm) and female gamete (the egg), unite and the genetic material combines.
Gene – A part of the DNA which controls the hereditary characteristics of an organism. Individual genes consist of a unique sequence of about 2000 bases which permits the cell to make a particular protein. Each individual has two sets of genes (one set from each parent) and passes this on to each of its offspring.
Genetic – Describes something to do with genes and inheritance.
Gene pool – All of the genes that exist within an inbreeding population.
Genome – A complete set of chromosomes, i.e. genes within a living organism.
Genotype – The genes found in the cells on an individual. The genetic makeup of an individual will influence the appearance of phenotype of the individual.
Heritability – The transmission, or passing on, of features controlled by genes from both parents to their offspring.
Heterozygous – An individual that has two different alleles of a gene for a particular characteristic. If one allele is recessive and the other dominant, then the effect cause by the dominant allele will be apparent.
Homozygous – An individual that has identical alleles for a particular characteristic. Recessive characteristics will only show if an individual is homozygous for that characteristic.
Locus – Position on matching maternal and paternal chromosomes at which alleles of the same gene are found.
Marker – A component of a genetic map which uniquely identifies a locus.
Maternal – Something belonging to, or coming from, the mother (dam)
Microsatellite – A region of DNA which possesses an unusual base sequence where, two, three or four bases are continually repeated.
Monogenic – A characteristic controlled by a single gene.
Mutation – A change in the base sequence of DNA caused by an error in copying or some other factor. A mutation may be passed onto offspring.
Nucleus – The control centre of the cell which contains the chromosomes.
Paternal – Describes something belonging to, or coming from the father (sire).
Phenotype – The overall appearance of an individual, i.e. looks and behaviour. The phenotype is the physical expression of an individual’s genotype.
Polygenic – A characteristic controlled by more than one gene.
Protein – One of a group of chemical substances that build and run cells. Proteins are built of amino acids using instructions encoded in genes.
Recessive Mutation – A mutation that is masked by the presence of a normal counterpart. These are only expressed when there are two copies of the mutation.
Sex chromosomes – Chromosomes involved in determining the sex of the animal, i.e. females have two X chromosomes and males posses one X and one Y chromosome.
Sex linked inheritance – Inheritance of characteristics that are determined by genes present on either the X or Y chromosome.
Somatic – All cells in the body apart from the reproductive cells (gametes).
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