1. DAPI
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DAPI
Properties
Molecular formula C16H15N5
Molar mass 277.324
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Except where noted otherwise, data are given for materials in
their standard state (at 25 °C, 100 kPa)
Infobox references
DAPI or 4',6-diamidino-2-phenylindole is a fluorescent stain that binds strongly to A-T rich
regions in DNA. It is used extensively in fluorescence microscopy. DAPI can pass through an
intact cell membrane therefore it can be used to stain both live and fixed cells, though it passes
through the membrane less efficiently in live cells and therefore the effectiveness of the stain is
lower.
[edit] History
DAPI was first synthesised in 1971 in the laboratory of Otto Dann as part of a search for drugs
to treat trypanosomiasis. Although it was unsuccessful as a drug, further investigation indicated
it bound strongly to DNA and became more fluorescent when bound. This led to its use in
identifying mitochondrial DNA in ultracentrifugation in 1975, the first recorded use of DAPI as
a fluorescent DNA stain.[1]

2. Strong fluorescence when bound to DNA led to the rapid adoption of DAPI for fluorescent
staining of DNA for fluorescence microscopy. Its use for detecting DNA in plant, metazoa and
bacteria cells and virus particles was demonstrated in the late 1970s, and quantitative staining of
DNA inside cells was demonstrated in 1977. Use of DAPI as a DNA stain for flow cytometry
was also demonstrated around this time.[1]
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Mutagenesis (pron.: /mjuː dʒɛnɪsɪs/) is a process by which the genetic information of an
təː
organism is changed in a stable manner, resulting in a mutation. It may occur spontaneously in
nature, or as a result of exposure to mutagens. It can also be achieved experimentally using
laboratory procedures. In nature mutagenesis can lead to cancer and various heritable diseases,
but it is also the driving force of evolution. Mutagenesis as a science was developed based on
work done by Hermann Muller, Charlotte Auerbach and J. M. Robson in the first half of the 20th
century.[1]
Karyotype
A karyotype (Greek karyon = kernel, seed or nucleus) 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.[1][2][3]
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.[4] The
preparation and study of karyotypes is part of cytogenetics.
Karyogram of human male using Giemsa staining
The study of whole sets of chromosomes is sometimes known as karyology. The chromosomes
are depicted (by rearranging a microphotograph) in a standard format known as a karyogram or
idiogram: in pairs, ordered by size and position of centromere for chromosomes of the same size.

3. The basic number of chromosomes in the somatic cells of an individual or a species is called the
somatic number and is designated 2n. Thus, in humans 2n = 46. In the germ-line (the sex cells)
the chromosome number is n (humans: n = 23).[2]p28
So, in normal diploid organisms, autosomal chromosomes are present in two copies. There may,
or may not, be sex chromosomes. Polyploid cells have multiple copies of chromosomes and
haploid cells have single copies.
The study of karyotypes is important for cell biology and genetics, and the results may be used in
evolutionary biology and medicine. Karyotypes can be used for many purposes; such as to study
chromosomal aberrations, cellular function, taxonomic relationships, and to gather information
about past evolutionary events.
Diagnosis
Diagnosis is the identification of the nature and cause of anything. Diagnosis is used in many
different disciplines with variations in the use of logics, analytics, and experience to determine
the cause and effect relationships. In systems engineering and computer science, diagnosis is
typically used to determine the causes of symptoms, mitigations for problems and solutions to
issues.[1][2]
Cytogenetics
A metaphase cell positive for the BCR/ABL rearrangement using FISH
Cytogenetics is a branch of genetics that is concerned with the study of the structure and
function of the cell, especially the chromosomes.[1] It includes routine analysis of G-banded
chromosomes, other cytogenetic banding techniques, as well as molecular cytogenetics such as
fluorescent in situ hybridization (FISH) and comparative genomic hybridization (CGH).