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.
This is called the interphase. Just before cell division, the chromosomes are duplicated. This is called the S phase. Then mitosis occurs. To facilitate separation of DNA, the chromosomes condense and become visible under light microscopy.Only during the M phase (mitosis) chromosomes are visible.uring interphase, the cell is essentially preparing for mitosis. Thus, the nuclear membrane is still intact. The cell is merely replicating its DNA and chromosomes. During mitosis itself, however, the nuclear membrane breaks down so the chromosomes become visible under a microscope.