The result of a calibration may be recorded in a document, sometimes called a calibration certificate or a calibration report. See CLAS Requirements Document 6 Requirements for Calibration Certificates issued by CLAS Laboratories.
DNA and histone proteins are packaged into structures called chromosomes. In the nucleus of each cell, the DNA molecule is packaged into thread-like structures called chromosomes.Each chromosome is made up of DNA tightly coiled many times around proteins called histones that support its structure.Chromosomes are not visible in the cellâs nucleusânot even under a microscopeâwhen the cell is not dividing.However, the DNA that makes up chromosomes becomes more tightly packed during cell division and is then visible under a microscope.n the nucleus of each cell, the DNA molecule is packaged into thread-like structures called chromosomes. Each chromosome is made up of DNA tightly coiled many times around proteins called histones that support its structure.
Once cell division is triggered, the DNA inside the nucleus duplicates and the chromatin within the cells nucleus begins to condense. Prior to prophase, DNA is visible under a light microscope as a dark blur. Before prophase, a normal cell contains 23 pairs of chromosomes. After prophase, the cell contains 46 pairs of chromosomes -- two copies of each pair -- known as sister chromatids, joined at a centromere to form an X-shape.