Genetic analyses include molecular technologies such as
PCR,
RT-PCR,
DNA sequencing, and
DNA microarrays, and
cytogenetic methods such as
karyotyping and
fluorescence in situ hybridisation.
DNA sequencing DNA sequencing is essential to the applications of genetic analysis. This process is used to determine the order of
nucleotide bases. Each molecule of DNA is made from
adenine,
guanine,
cytosine and
thymine, which determine what function the genes will possess. This was first discovered during the 1970s. DNA sequencing encompasses biochemical methods for determining the order of the nucleotide bases, adenine, guanine, cytosine, and thymine, in a DNA oligonucleotide. By generating a DNA sequence for a particular organism, you are determining the patterns that make up genetic traits and in some cases behaviors. Sequencing methods have evolved from relatively laborious gel-based procedures to modern automated protocols based on dye labelling and detection in capillary
electrophoresis that permit rapid large-scale sequencing of genomes and transcriptomes. Knowledge of DNA sequences of genes and other parts of the genome of organisms has become indispensable for basic research studying biological processes, as well as in applied fields such as diagnostic or forensic research. The advent of DNA sequencing has significantly accelerated biological research and discovery.
Cytogenetics Cytogenetics is a branch of genetics that is concerned with the study of the structure and function of the cell, especially the chromosomes.
Polymerase chain reaction studies the amplification of DNA. Because of the close analysis of chromosomes in cytogenetics, abnormalities are more readily seen and diagnosed.
Karyotyping A
karyotype is the number and appearance of chromosomes in the nucleus of a eukaryotic cell. The term is also used for the complete set of chromosomes in a species, or an individual organism. Karyotypes describe the number of chromosomes, and what they look like under a light microscope. Attention is paid to their length, the position of the
centromeres, banding pattern, any differences between the sex chromosomes, and any other physical characteristics.
Karyotyping uses a system of studying chromosomes to identify genetic abnormalities and evolutionary changes in the past.
DNA microarrays A
DNA microarray is a collection of microscopic DNA spots attached to a solid surface. Scientists use DNA microarrays to measure the expression levels of large numbers of genes simultaneously or to genotype multiple regions of a genome. When a gene is expressed in a cell, it generates
messenger RNA (mRNA). Overexpressed genes generate more mRNA than underexpressed genes. This can be detected on the microarray. Since an array can contain tens of thousands of probes, a microarray experiment can accomplish many genetic tests in parallel. Therefore, arrays have dramatically accelerated many types of investigations.
PCR The polymerase chain reaction (PCR) is a biochemical technology in molecular biology to amplify a single or a few copies of a piece of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence. PCR is now a common and often indispensable technique used in medical and biological research labs for a variety of applications. These include
DNA cloning for sequencing, DNA-based
phylogeny, or functional analysis of genes; the diagnosis of
hereditary diseases; the identification of genetic fingerprints (used in forensic sciences and paternity testing); and the detection and diagnosis of infectious diseases. == Applications ==