Definitions Flashcards
Alleles
alternative forms of a genetic locus (one allele from each parent)
amplicon
the amplified product of a PCR reation
Amplification
an increase in the number of copies of a specific DNA fragment (e.g. during PCR)
Autosome
a chromosome not involved in sex determination
Base
the individual monomers in nucleic acids (deoxyribonucleotides or ribonucleotides in DNA or RNA respectively)
Base sequence
order of nucleotide bases in a DNA molecule
Bioinformatics
application of computers and computational expertise to analyse, visualise, catalogue and interpret large biological datasets in the context of the genome sequences of humans and other species
Biomarker
a characteristic that can be objectively measured and evaluated as an indicator of normal biologic processes, pathogenic processes, or pharmological responses to a therapeutic intervention
Carrier
a person who has inherited a genetic trait or mutation but does not display the disease
cDNA
complementary or copy DNA synthesise from a mRNA template using reverse transcriptase
Chromosome
A sub-cellular structure made up of tightly coiled DNA which contains many genes
Complementary
nucleic acid base sequences that can form a double stranded sequences structure by matching base pairs
Complex disease
a phenotype that results from the actions of multiple genes and their interaction with other factors such as lifestyle and the environment
Copy number variation
the differing number of copies of a particular DNA sequence in the genomes of different individuals
Cytogenetics
the study of the relationships between the structure and number of chromosomes and variation in genotype and phenotype
Diagnostic te#st
particular tests that are able to identify a recognised condition
DNA
‘deoxyribonucleic acid’ chemical comprise the genetic material of all cellular organisms
DNA sequencing
determination of the order of bases in a DNA molecule
Electrophoresis
a process by which molecules can be separated according to size and electrical charge by applying an electric current to them (each molecule travels through medium at different rate)
Endonuclease
an enzyme that cleaves a nucleic acid at internal sites
Eukarytote
cell or organisms with a distinct membrane bound nucleus
Exons
protein coding sequences of gene
Exonuclease
an enzyme that cleaves a nucleic acid sequentially from a free end
Expressed gene
those genes that are transcribed into mRNA
Gene
basic physical and functional unit found in chromosomes
Gene expression
process where a gene is activated at a particular time and place so that its functional product is produced
Genetic counselling
providing an assessment of heritable risk factors and information to patients and their relatives concerning the consequences of a disorder, the chance of developing or transmitting it, how to cope and ways of preventions, treatment and management
Genetic predisposition
having some genetic factor(s) that may make an individual more likely to develop a particular condition than the general population
Genetic screening
testing a population group to identify a subset of individuals at high risk for having or transmitting a specific condition than the general population
Genetic test
an analysis performed on human DNA, RNA, genes and/or chromosomes to detect heritable or acquired genotypes
Genome
unique genetic code of hereditary material of an organism, carried by a set of chromosomes in the nucleus of each cell
Genotype
specific genetic makeup of an indivual at a particular location in their genome (usually refers to a particular pair of alleles at a specific locus)
Haplotype
a particular combination of alleles or sequence variations that are cloecly linked (ie are likely to be inherited together) on the same chromosome
Heterozygosity
the presence of different alleles at one or more loci on homologous chromosomes
Homozygosity
the presence of identical alleles at one or more loci on homologous chromosomes
Hybridisationn
the process of joining two complementary strands of DNA, or one each of DNA and RNA, along their lengths to form a double stranded molecule
Introns
non-coding sequences which interrupt the protein coding sequences of a gene
Karyotype
metaphase chromosomes from an individual arranged in a standard format
Ligase
an enzyme that can rejoin a broken phosphodiester bond in a nucleic acid; requires 5’ phosphate and a 3’ hydroxyl group in immediately adjacent nucleotides
Linkage
the close proximity of two or more genetic markers on a chromosome
Locus
the specific site on a chromosome at which a particular gene of other DNA landmark is located
Marker
an identifiable physical location on a chromosome, the inheritance of which can be assessed
Microarrary
(=gene chip/DNA chip) high throughput technology that enables the detection of gene expression levels or the detection of SNPs within the genome
mRNA
(messenger RNA) RNA that is a template for protein synthesis
Mutation
a change to the nucleotide sequence of the genetic material of an organism, compared to a standard reference sequence (in medical genetics, a mutation often means a change in the sequence that is disease-causing)
Nucleotide
one of the building blocks of DNA
Oligonucleotide
a short (
PCR
(polymerase chain reaction) an in vitro technique for rapidly synthesising large quantities of a given targeted DNA segment. Involves separating DNA into two complementary strands, binding a primer to each, then use heat stable DNA polymerase to create double stranded DNA from each single strand (process repeated to amplify the target sequence)
Penetrance
likelihood that a person carrying a particular mutant gene will have an altered phenotype such as a genetic disorder
Pharmacogenetics
study of the way in which variation in individual genes affects drug metabolism and responsiveness, and the application of this information into clinical practice
Phenotype
the observable properties and physical characteristics of an organism based on a combination of genetic traits and environmental factors
Polymerase
enzyme that catalyses the synthesis of DNA or RNA from a single stranded template and free deoxyribonucleotides
Polymorphism
a difference in DNA sequence amongst individuals in at least 1% of the population
Polygenic trait
a trait affected by many genes, with no one gene having a large influence
Prenatal test
procedure done to determine the presence of disease of defect in a foetus
Primer
a short, pre-existing single-stranded oligonucleotide chain to which new deoxyribonucleotides can be added by DNA polymerase
Probe
single stranded DNA/RNA molecule used to detect its complementary sequences by hybridisation
Prokaryote
cell or organism lacking a distinct membrane bound nucleus
Protein
molecule composed of amino acids linked together in a particular order specified by genes
Proteome
complete set of proteins encoded by the genome
Psuedogene
a region of DNA that shows extensive similarity to a known gene, but which cannot be itself function
Recombinant DNA
combination of DNA molecules of a different origin
Recombination
process by which DNA is exchanged between pairs of equivalent chromosomes (homologues) during meiosis
RNA
‘ribonucleic acid’ chemical that is copied from the DNA on an individuals chromosomes (transcription) that carried the genetic information required to produce cellular proteins
Sensitivity
proportion of individuals with a disease phenotype who test positive
SNP
‘single nucleotide polymorphism’ a variation in a DNA sequence that occurs when a single nucleotide in a genome is altered in at least 1% of the population
Southern blotting
a technique used to transfer electrophoretically separated fragments of DNA, after denaturation, from the gel to an absorbent sheet of material to which the DNA binds
Specificity
the proportion of individuals without a disease phenotype who test negative
Tandem repeats
multiple copies of the same sequence on a chromosome, often found in microsatellite markers
Transcriptome
the complete set of RNAs transcribed from the genome
