The chromosomes are now referred to as pairs of chromatids which are joined at a centromere.Ģ. The chromosomes condense (shorten and become thicker) and become visible as long thin threads. It is only during the first phase of mitosis, called prophase, that the chromosomes start to condense and become visible.ĭuring prophase the following changes take place:ġ. The chromosomes are not visible at interphase because the chromosome material, chromatin, is dispersed throughout the nucleus. There is considerable metabolic activity as these processes need energy in the form of ATP. Just before the next cell division the chromosomes replicate so that each then consists of two chromatids joined together by the centromere. The amount of DNA is doubled during this period. This is the longest part of the cell cycle during which a cell increases in size and produces organelles which will be divided between the two new daughter cells. Lastly, cytokinesis occurs whereby the cell splits down the middle leading to the formation of two new daughter cells. Once interphase is complete, mitosis occurs leading to division of the DNA to either pole of the cell. Interphase is a very important and highly metabolically active stage of the cell cycle where the DNA replicates and organelles are replicated. The cell cycle is a continuous process but for convenience of description it is subdivided into three main processes: interphase, mitosis and cytokinesis. Dividing cells undergo a regular pattern of events known as the cell cycle. Cell division by mitosis leads to production of two daughter cells that are genetically identical to the parent cell.
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