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Glossary
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| 3' (3 Prime) |
| Region downstream of sequence/gene. The end of a nucleic acid chain containing a 3' hydroxyl (-OH) group |
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| 5' (5 Prime) |
| Region upstream of sequence/gene. The end of a nucleic acid chain containing a 5' hydroxyl group |
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A (Adenine)  |
| A nitrogenous base. Pairs with Thymine in DNA molecules |
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| Additive Genetic Effects |
| When the combined effects of alleles at different loci are equal to the sum of their individual effects |
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| Allele |
| Given form of a gene that occupies a specific position or locus on a chromosome. Variant forms of genes occurring at the same locus are said to be alleles of one another. |
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| Allele Frequency |
| The percentage/frequency of a given allele in a defined population |
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| Alleles |
| Alternate forms of a gene or DNA sequence, which occur on either of two homologous chromosomes in a diploid organism. |
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| Allelic Associations |
| See Linkage Disequalibrium |
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| Allelotype |
| Allele Frequency - as determined in a single reaction on a single equimolar pooled sample |
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| Allotype |
| The protein product (or the result of its activity) of an allele which may be detected as an antigen in another member of the same species. Example: Immunoglobulins, histocompatibility antigens) |
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| Alu Sequences |
| Common set of dispersed DNA sequences found throughout the human genome; each about 300 bases long and repeated at least 500,000 times. Speculated to have originated from viral RNA sequences that integrated into human DNA thousands of years ago |
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| Ancestral Segment |
| Genetic block of linked loci which is preserved in a given population and has no internal recombination. |
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| Anticodon |
| Nucleotide base triplet in a transfer RNA molecule that pairs with a complementary base triplet, or codon, in a messenger RNA molecule |
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| Antisense RNA |
| Complementary RNA sequence - binds to (sense) mRNA molecule, blocking translation |
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| ASA (Allele Specific Amplification) |
| Process where one allele/gene/region is amplified in a PCR reaction at a different rate than the other allele. Results in biased representation - also termed allelic bias or biased amplification |
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| ASH (Allele Specific Hybridization) |
| Process where through accident or design a primer will hybridize preferentially to one allele form over another |
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| ASPA (Affected Sib Pair Analysis) |
| Genetic analysis based on two siblings affected by a disease. Genetic markers evenly spaced throughout the genome are genotyped. For each locus the sibs could share 0, 1 or 2 alleles with expected ratios of each of these outcomes being 25%, 50% and 25% respectively. If the parental genotypes are known to differ at the locus and the two sibs share an allele, they are identical by descent (IBD). Using sib pair data from a number of families, the IBD frequencies at each locus can be determined and tested to see whether they differ from the value expected from random segregation. This can indicate linkage of that marker to a disease-causing allele. The power of this analysis increases with increased numbers of sib pairs. |
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| Assembly (See Shotgun Sequencing) |
| Process where contig sequences are joined to yield large sections of completed sequence |
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| Association Study |
| Comparison of allele/marker freqency differences between two large populations (typically case and control). Populations are composed sharing a common phenotype or trait. Intent is to identify alleles with statistically significant freqency between population to locate trait associated genes. |
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| Autosome |
| Chromosome that is not involved in sex determination |
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| Autosomes |
| All the chromosomes in the genetic complement (genome) with the exception of the sex chromosomes |
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| BAC (Bacterial Artificial Chromosome) |
| Clone used to generate genome library -supports 100-400 kb insert |
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| Backcross |
| Crossing an organism with one of its parent organisms |
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| Bacteriophage |
| A virus whose host is a bacterium. Also called phage
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| Base Pair |
| Two nitrogenous bases held together by weak bonds. In DNA, A pairs with T and C pairs G |
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| Bi-allelic |
| Presence of two alleles at a locus |
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| C (Cytosine) |
| A nitrogenous base. Pairs with Guanine in DNA molecules. |
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| Candidate Gene |
| Gene, family of genes or pathway identified as having likley association with a trait/phenotype. Generally targeted in association studies to minimise number of SNPs scanned. |
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| Case Control Study |
| Involves identifying patients who have the outcome of interest (cases) and control patients without the same outcome, and looking back to see if they had the exposure of interest. |
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| cDNA (copy DNA) |
| DNA strand copied from mRNA using reverse transcriptase. |
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| cDNA library |
| Library composed of complementary copies of cellular mRNAs. Represents all of the expressed DNA in a cell |
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| Centromere |
| Portion of chromosome to which spindle fibers attach during mitotic and meiotic division |
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| Chromosome |
| Self-replicating genetic structure composed primarily of a single DNA molecule, a tightly coiled strand of DNA, condensed into a compact structure in vivo by complexing with accessory histones proteins |
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| Chromosome Walking |
| Working from a flanking DNA marker, overlapping clones are successively identified that span a chromosomal region of interest |
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| Clone |
| Exact genetic replica of a specific gene or an entire organism |
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| cM (Centimorgan) |
| Map unit or unit of genetic distance on a chromosome. One centimorgan is equivalent to a 1% frequency of recombination between two linked genes |
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| Cohort Studies |
| Involves identification of two groups (cohorts) of patients, one which did receive the exposure of interest, and one which did not, and following these cohorts forward for the outcome of interest. |
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| Complex Disease |
| Multiple loci and environmental effects which each modestly contributing disease progression |
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| Codon |
| Group of three nucleotides (triplet) that specifies amino acid during translation of an mRNA into a polypeptide |
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| Contig/Contig Block/Contig Map (Contiguous Map) |
| The alignment of sequence data from large, adjacent regions of the genome to produce a continuous nucleotide sequence across a chromosomal region |
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| cSNP (coding/control SNP) |
| SNP located in a coding or control region of a gene |
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| Cytosine |
| A nitrogenous base. Pairs with Guanine in DNA molecules. |
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| D' (D-Prime Score) |
| Normalized measure of Allelic Association shown as a confidence score rating linkage disequalibrium/association between marker/genes. Score of 1 indicates perfect linkage disequalibrium and 100% co-transfer. |
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| Da. (Dalton) |
| A unit of measurement equal to the mass of a hydrogen atom, 1.67 x 10E-24 gram/L (Avogadro's number) |
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| Deletion |
| The loss of a segment of genetic material from a chromosome. |
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| Deletion Mapping |
| The use of overlapping deletions to localize the position of an unknown gene on a chromosome of linkage map. |
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| ddNTP (di-deoxy Nucleotide Triphosphate) |
| Deoxynucleotide that lacks a 3' hydroxyl group, and is unable to form a 3'-5' phosphodiester bond necessary for chain elongation |
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| Diploid |
| 2 chromosome/gene copies |
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| Discordant |
| Twins are said to be discordant with respect to trait if one shows the trait and the other does not. |
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| dNTP (deoxy Nucleotide Triphosphate) |
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| Dominance variance |
| Genetic variance for a polygenic trait in a given population attributed to the dominance effects of contributing genes. |
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| Downstream |
| Region extending in a 3' direction from a gene |
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| Epigenetics |
| Phenotype effects derived by alteration outside of sequence - ie DNA methylation |
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| eSNP (exonic SNP) |
| SNP located in an exon of a gene |
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| EST (Expressed Sequence Tag) |
| Small sequence from an expressed gene that can be amplified by PCR. Act as physical markers for cloning and full length sequencing of the cDNAs of expressed genes. Typically identified by purifying mRNAs, converting to cDNAs, and then sequencing a portion of the cDNAs |
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| Etiology |
| Study of the origin and progression of a disease |
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| Exo (Exonuclease) |
| Enzyme that digests DNA |
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| Exon |
| DNA sequence that is ultimately translated into protein |
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| Finishing |
| (See Shotgun Sequencing) |
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| Flanking Region |
| DNA sequences extending on either side of a specific locus or gene |
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| Founder Population |
| Original (generally small) population of individuals from which a larger population developed |
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| Frameshift |
| Small nucleotide insertion or deletion variation - typically 1 or 2 bases - shifts reading frame |
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| G (Guanine) |
| Nitrogenous base. Pairs with cytosine in DNA molecules. |
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| Gametic disequilibrium |
| The non-random distribution into the gametes in a randomly mating population of the alleles of genes occupying different loci. The non-random distribution may result from linkage of the loci in question or because the loci interact with respect to their effects on fitness. |
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| Gene |
| A locus on a chromosome that encodes a specific protein or several related proteins. Considered the functional unit of heredity |
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| Gene Amplification |
| The presence of multiple genes. One mechanism through which proto-oncogenes are activated in malignant cells - Not PCR |
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| Gene Flow |
| Exchange of genes between different but (usually) related populations |
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| Gene Library |
| Collection of cloned DNA fragments created by restriction endonuclease digestion that represent part or all of an organismís genome |
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| Gene Linkage |
| The hereditary association of genes located on the same chromosome |
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| Genetic Drift |
| Random variation in gene frequency from one generation to another |
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| Genetic Imprinting |
| The different expression patterns exhibited by a single gene; the differential expression is modulated by the differential methylation of cytosine residues (inherited from each parent) near the promoter of that gene |
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| Genome |
| Genetic complement contained in the chromosomes of a given organism, usually the haploid chromosome state. |
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| Genome Wide Scan |
| Investigation of large number of alleles that are evenly disperesed across the entire genome. Gives a genome wide view of all genetic variation. |
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| Genomics |
| Analysis of the entire genome of a chosen organism |
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| Genotype |
| The structure of DNA that determines the expression of a trait. Strictly, all of the genes possessed by an individual. In practice, the particular alleles present in a specific genetic locus. |
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| Guanidine-HCL |
| Strong protein denaturant |
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| HAC (Human Artificial Chromosome) |
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| Haploid |
| Haploid - single copy of each chromosome |
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| Haplotype |
| Particular combinations of alleles/markers observed. Common haplotype present in population at frequency >5% |
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| Haplotype Block |
| Region in high linkage disequalibrium with evidence of minimal recombination. Can be of variable length but with few common haplotypes, typically 3-5. |
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| H-W (Hardy Weinberg) |
| Statistical measure that population is stable/ in equalibrium. Usually called a Medelian population. (p2+2pq+q2 = 1) |
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| Heteroduplex |
| Hybrid structure formed by the annealing of two DNA strands (or an RNA and DNA) that have sufficient complementarity in their sequence to allow hydrogen bonding. |
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| Heterozygote |
| Individual having two different copies of an allele/marker/gene |
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| Homozygote |
| Both (all) copies of allele/marker/gene are the same. An organism whose genotype is characterized by two identical alleles of a gene |
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| HPA (Hydroxy Picolinic Acid) |
| Matrix used for MALDI-TOF MS of DNA |
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| htSNP (Haplotype Tag SNP) |
| SNP that can be used to identify/tag haplotype |
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| IBD (Identical by Descent) |
| (see Sib Pairs - ASPA) |
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| In silico |
| Computer mediated. The use of computers to simulate, process, or analyse a biological experiment |
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| in vitro |
| Occurring outside the living organism (literally, in glass). Typically an experiment performed in a test tube or other artificially designed environment |
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| In Vivo |
| Occurring within a living organism |
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| Inbreeding |
| The mating of closely related individuals. Consequence of inbreeding is that individuals become progressively more homozygous for genes |
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| incomplete penetrance |
| The situation in which an allele is expressed only if certain factors are present in the environment. The triggering of genetically inherited diabetes by obesity is an example. |
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| InDel (Insertion/Deletion mutation) |
| Small nucleotide insertion or deletion variation - typically only a few bases - may shift reading frame |
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| Intergenic Regions |
| DNA sequences located between genes. Comprise large percentage of human genome. No known function |
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| Intron |
| Noncoding DNA sequence within gene. Initially transcribed into messenger RNA but later snipped out |
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| Inverted Repeats (see Palindromes) |
| Two identical DNA sequences oriented in opposite directions on the same DNA molecule. Adjacent inverted repeats are known as a palindromes |
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| iSNP (intronic SNP) |
| SNP located in an intron of a gene |
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| isSNP (In-silico SNP) |
| SNP identified by comparing identified Sequenom of 2 or more individuals. Only putative until prior to validation |
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| Junk DNA |
| Term used to describe the excess DNA that is present in the genome beyond that required to encode proteins. A misleading term since these regions are likely to be involved in gene regulation, and other as yet unidentified functions |
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| Karyotype |
| The constitution (typically number and size) of chromosomes in a cell or individual |
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| Knock-out/Knock-in Mice |
| Knock out mouse is one in which single gene of choice is inactivated or "knocked out" in a manner that leaves all others unaffected. Such mice provide a way to delineate the function of a gene. Knock-in mouse has functional copy of gene under investigation added to genome to assess phenotype effect. |
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| LASER |
| Light Amplification by Serial Emission of Radiation |
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| LD (Linkage Disequalibrium) |
| See below |
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| Lead Compound |
| Compound that could potentially be converted to a new drug by optimizing its beneficial effects and minimizing its toxicity and side effects. Identifying lead compounds (typically by high-throughput screening) is the first step in the drug discovery process once a useful therapeutic target has been identified and validated through genomics and pharmacology. |
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| Lead Optimization |
| The process of converting a putative lead compound ("hit") into a therapeutic drug with maximal activity and minimal side affects, typically using a combination of computer-based drug design, medicinal chemistry and pharmacology |
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| Leucine Zipper |
| Protein motif which binds DNA in which 4-5 Leucines are found at 7 amino acid intervals. This motif is present typically in transcription factors and other proteins that bind DNA. |
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| Linkage |
| Frequency of coinheritance of a pair of genes and/or genetic markers. Provides a measure of their physical proximity to one another on a chromosome. The greater association in inheritance of 2 or more non-allelic genes than is to be expected from independent assortment. Genes linked because they reside on the same chromosome.
Condition in which tow or more nonallelic genes tend to be inherited together. Linked genes have their loci along the same chromosome, do not assort independently, but can be separated by crossing over. |
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| Linkage Disequalibrium |
| The non-random distribution into the gametes of a population of the alleles of genes that reside on the same chromosome.
The simplest situation would involve a pair of alleles at each of two loci. If there is random association between the alleles, then the frequency of each gamete type in a randomly mating population would be equal to the production of the frequencies of the alleles it contains. The rate of approach to such a random association, or equilibrium, is reduced by linkage and hence linkage is said to generate disequilibrium. |
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| Linkage Group |
| The group of genes having their loci on the same chromosome |
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| Linkage Map |
| A linear map of the relative positions of genes along a chromosome. Distances are established by linkage analysis, which determines the frequency at which two gene loci become separated during chromosomal recombination |
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| Linkage Study |
| Study to determine linkage between genetic markers. |
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| Locus (pl: loci) |
| Specific location or site/marker on a chromosome. At a given locus, any one of the variant forms of a gene may be present. The variants are said to be alleles of that gene |
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| LOD |
| Abbreviation for “logarithm of odds favoring linkage”. A pedigree is analyzed to determine the likelihood of probability (Pr) that two genes show a specified recombination value (r ). Next, the likelihood (Pi) is calculated under the assumption that the genes assort independently. The LOD score z=log10 (Pr/Pi). A Z score of +3 is considered evidence of linkage. LIPED is a computer program for calculating this. |
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| LOD Score (Logarithm of the Odds Score) |
| Measure of markers being linked to a particular distance, divided by the odds that they’re linked at 50% coinheritance. (50% coinheritance = not linked at all.) LOD of 1 = suggestive, LOD of 2 = probable, LOD of 3 = more than probable, LOD of 4 = proof. |
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| Locus |
| The position that a gene occupies in a chromosome or within a segment of genomic DNA. |
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| LOH (Loss of Heterozygosity) |
| Very large deletion or chromosomal loss (non-matched recombination event) results in hemizygote |
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| MALDI |
| Matrix Assisted Laser Desorption/Ionization |
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| Map Unit (see cM) |
| A measure of genetic distance between two linked genes that corresponds to a recombination frequency of 1%. A measure of genetic distance, corresponding to a recombination frequency of 1 percent, i.e., centromorgan ( a unit distance between genes on chromosomes. One centromorgan represents a value of 1 percent crossing over between two genes. |
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| Marker |
| Loci used as a study indicator |
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| Meiosis |
| Process of cell division in which single cell ultimately produces four daughter cells each of which contains half of the number of chromosomes of the parent cell. |
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| Tm (Melting Temp) |
| Temperature at which half the stands in dsNDA will be in duplex form |
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| Mendelian Trait |
| A trait that is transmitted in accordance with Mendel's laws of genetics |
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| Methylation |
| The addition of -CH3 (methyl) groups to a target site. Typically such addition occurs on to the cytosine bases of DNA |
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| Microsatellite |
| Tandem repeat of generally 2-4 bases. Used as genetic markers as repeat units variable |
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| Minisatellites |
| Tandom arrays of moderately repetitive (5-50 repeats) short (10-20 bases) DNA sequences dispersed throughout the genome and clustered near telomeres. Their degree of repetition is two to several hundred. Loci number in the thousands, but each loci shows a distinctive repeat unit. Also known as microsatellite and VNTR. |
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| Mismatch |
| Incorrect association of nucleotides. Ie C with A or G. Most common is G with T. |
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| Mitosis |
| Process of cell division in which a single cell produces two daughter cells which are genetically identical to one another, and to the original parent cell. |
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| mRNA (Messenger RNA) |
| Ribonucleic acid transcription product from gene that encodes protein to be synthesized when translated by ribosome complex. Expression levels (transcription rate and stability are used in genetic/cellular regulation mechanisms) |
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| MS (Mass Spectrometry) |
| Technology for accurately sizing molecules to the atomic level. One hydron atom = 1 Da. |
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| Mutation load |
| The genetic disability sustained by a population due to the accumulation of deleterious genes generated by recurrent mutation |
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| Mutation frequency |
| The proportion of mutants in a population, or a given locus |
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| Mutation rate |
| The number of mutation events per gene unit time |
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| Multiplexing |
| Process of analyzing multiple SNPs/loci for a single individual in a common/single reaction |
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| Non-Synonymous SNP |
| eSNP that DOES result in an amino acid change |
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| Nucleotide |
| Base unit of nucleic acids (DNA/RNA). deoxyadenylic acid (dATP), deoxycytidylic acid (dCTP), deoxyguanylic acid (dGTP), and deoxythymidylic acid (dTTP). (dUTP replaces dTTP in RNA) |
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| Oligo (Oligonucleotide) |
| DNA polymer composed of only few nucleotides (generally less than 100) |
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| ORF (Open Reading Frame) |
| A long DNA sequence that is uninterrupted by a stop codon and encodes mRNA that will intern be translated into part or all of a protein |
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| P1 |
| The symbol denoting the immediate parents of the F1 generation. P1 and P2 are used to denote the grandparental and great-grandparental, respectively. |
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| Palindrome (Palindromic Sequence) |
| DNA locus whose 5'-to-3' sequence is identical on each DNA strand. The sequence is the same when one strand is read left to right and the other strand is read right to left. |
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| Passive equilibrium |
| An unstable equilibrium resulting from selective neutrality of alleles at a genetic locus, as occurs in Hardy-Weinberg equilibrium. Also called neutral equilibrium. |
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| PCR (Polymerase Chain Reaction) |
| Process of exponentially amplifying DNA to generate sufficient sample amount for diagnostic analysis |
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| Pedigree |
| Diagram mapping the genetic history of a particular family/related individuals |
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| Penetrance |
| Chance that an allele change in coding sequence results in a particular disease |
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| Pharmacogenomics |
| 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. |
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| Phenotype |
| Observable characteristics of an organism, the expression of gene alleles (genotype) as an observable physical or biochemical trait |
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| PHRED |
| Quality score for DNA sequence accuracy developed by Phil Green (q = -10 log p). Score of over 20 is generally considered acceptable. Score of 30 or better indicates sequences are perfect. |
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| Physical Map |
| A map showing physical locations on a DNA molecule, such as restriction sites, and sequence-tagged sites. |
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| Point Mutation |
| A change in a single base pair of a DNA sequence in a gene |
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| Polygenic |
| Controlled by or associated with more than one gene - ie. complex diseases and pathways |
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| Polygenic inheritance |
| The transmission of phenotypic trait whose expression depends on the additive effect of a number of genes. |
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| Polymorphism |
| Variation. Presence of two or more different nucleotides at the same genetic position |
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| PolyPHRED |
| Quality score for polymorphisms detected by DNA sequencing. Developed by Phil Green. Indicates likelyhood of polymorphism being real and correct. |
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| Polyploid |
| More than one Chromosome copy (can result from chromosome replication without nuclear division) |
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| Pooling |
| The equimolar combination of many individuals from a population into a single sample. Used for rapid allele frquency determination. |
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| Population |
| Group of individuals/organisms belonging to the same species and capable of interbreeding |
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| Positional cloning |
| A process which, through gene mapping techniques, is able to locate a gene responsible for a disease when little or no information is known about the biochemical basis of the disease. |
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| Primer |
| Short DNA/RNA fragment annealed to single-stranded DNA, from which DNA polymerase extends strand |
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| Promoter |
| Gene control element extending 150-300 bp upstream from the transcription start site. Contains binding sites for RNA polymerase and a number of proteins that regulate the rate of transcription of the adjacent gene. |
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| Pseudogene |
| A gene that is very similar to a known gene at a different locus but is made nonfunctional by additions or deletions to its structure that prevent normal transcription or translation. |
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| pSNP (promoter SNP) |
| SNP located in a promoter region of a gene (generally 5-prime) |
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| punnett square |
| A simple graphical method of showing all of the potential combinations of offspring genotypes that can occur and their probability given the parental genotypes. |
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| Purine |
| A nitrogen- containing, single ring compound that occurs in nucleic acids. In DNA molecules - Adenine and Guanine |
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| Putative |
| Reputed or supposed - believed to be the case until proven otherwise |
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| P-value |
| Measure of statistical significance - lower the value the more statistically probably the event is accurate/real |
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| Pyrimidine |
| A nitrogen containing, double ring compound that occurs in nucleic acids. In DNA molecules - Cytosine and Thymine |
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| QTL (Quantitative Trait Locus) |
| Typically a marker used for selective breeding programs in agriculture. Linkage between a marker gene and a gene that influences quantitative trait |
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| Quantitative inheritance |
| Phenotypes that are quantitative in nature and continuous in distribution are referred to as quantitative characteristics. |
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| Recombination Frequency |
| Frequency at which crossing over occurs between two chromosomal loci--the probability that two loci will become unlinked during meiosis. The number of recombinations divided by the total number of progeny. This frequency is used as a guide in assessing the relative distances between loci on a genetic map. |
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| Reciprocal translocation |
| A chromosomal aberration in which homologous chromosomes exchange parts. |
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| RFLP (Restrictriction Fragment Length Polymorphism) |
| Differences in nucleotide sequence between alleles at a chromosomal locus result in restriction fragments of varying lengths detected by Southern analysis. |
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| SAP (Shrimp Alkaline Phosphatase) |
| Enzyme that dephospohorylates nucleotide triphosphates (hydrolyzes esters of phosphoric acid, removing phosphate group) |
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| Shotgun (Shotgun Sequencing) |
| Process of large scale sequencing where genome is randomly cleaved and transferred into libraries/clones. Sequencing is completed on each clone generating multiple coverage (X) as clone sequences overlap and assembled into contigs. Once have many contigs go to finishing process to fill in all gaps and derive complete genome sequence. |
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| Sib Pairs |
| Sibling Pairs |
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| Silent Mutation |
| Mutation in coding sequence that does not alter amino acid sequence |
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| SNP (Single Nucleotide Polymorphism) |
| Point Mutation - Single base substitution variation - present in population at a frequency at or above 1% |
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| Somatic Mutation |
| Variation in somatic cell lines (some cancer association). Mechanism used for IgG variation |
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| Standard deviation |
| A quantitative measure of the amount of variation in a sample of measurements from a population. |
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| STR (Short Tandem Repeat) |
| Repeat of generally 2-4 bases. Used as genetic markers as repeat units variable |
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| Stringency |
| Reaction conditions- temperature, salt, pH. Dictate annealing of single-stranded DNA/DNA, DNA/RNA, and RNA/RNA hybrids. At high stringency, duplexes form only between strands with perfect one-to-one complementarity; lower stringency allows annealing between strands with some degree of mismatch |
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| STS (Sequence Tagged Sites) |
| A unique (single-copy) DNA sequence used as a mapping landmark on a chromosome |
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| Stuttering alleles |
| Defective alleles that have segments which are doubled in their transmission from generation to generation. In the case of genetically inherited diseases, the result is increasingly severe symptoms in each generation. Also known as unstable alleles. |
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| Susceptibility Genes |
| Genes which directly influence an individual’s likelihood of developing a disease |
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| Subcloning |
| Process of tranferring a cloned DNA fragment from one vector to another |
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| Synonymous SNP |
| eSNP that does NOT result in an amino acid change (silent SNP) |
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| T (Thymine) |
| A nitrogenous base. Pairs with Adenine in DNA molecules |
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| Telomere |
| End portion of chromosome |
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| Thymine |
| A nitrogenous base. Pairs with Adenine in DNA molecules |
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| TOF (Time of Flight) |
| Time it takes MALDI analyzed samples to travel down vacuum tube - after desorption from samples target to detector. |
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| Transcription |
| Process of copying DNA into mRNA |
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| Transition |
| Exchange of purines (A for G, or G for A), or pyrimidine (T for C, or C for T) |
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| Translation |
| Converting genetic information of mRNA on ribosomes into a polypeptide. |
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| Translocation |
| Movement or reciprocal exchange of large-chromosomal segments, typically between two different chromosomes. A chromosome aberration, which results in a change in position of a chromosome segment with in the genome, but does not change the total number of genes present.
Intrachromosomal translocation
Interchromosomal translocation
Reciprocal or eucentric translocation
Is a two breakpoint aberration that results in an exact interchange of chromosomal segments between 2 non-homologous chromosomes and produces 2 monocentric translocated chromosomes. Non-reciprocal, or aneucentric- two breakpoints that reslts in decentric and acentric translocated chromosome. |
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| Translocation mapping |
| Gene mapping by the use of translocation chromosomes as markers. The semi-sterility that usually associated with structural translocation heterozygotes is a phenotypic marker that can be used to locate the position of the breakpoint of the translocation relative to other conventional gene markers. |
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| Transversion |
| Exchange of purine with pyrimidine (or vice versa) |
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| Tri-allelic |
| Presence of three alleles at a locus. Refers to polyploid with three different alleles exist at a gene locus |
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| TSC (The SNP Consortium) |
| Non-profit foundation organized for purpose of providing public genomic data. Mission to develop up to 300,000 SNPs distributed evenly throughout the human genome and to make the information related to these SNPs available to the public without intellectual property restrictions |
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| Upstream |
| Region extending in a 5' direction from a gene |
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| uSat (Microsatellite) |
| Repeat of generally 2-4 bases. Used as genetic markers as repeat units variable |
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| UTR (Un translated Region) |
| Region of DNA that is not convertered into protein |
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| Variance |
| When all values in a plus and minus deviations from the population mean. The variance is the mean of the squared deviations. |
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| Variation |
| Differences in the frequency of genes and traits among individual organisms within a population |
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| VNTR |
| Any gene whose alleles contain different numbers of tandomly repeated oligomer. Analyzed by restriction fragments. |
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| vSNP (Validated SNP) |
| SNP confirmed as truly polymorphic with frequency of greater than 1% in a given population |
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| X-linked Disease |
| Genetic disease caused by a mutation on the X chromosome. |
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| Y2H (Yeast 2 Hybrid) |
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| YAC (Yeast Artificial Chromosome) |
| Clone used to generate genome library -supports 100-1300 kb insert |
