Which helps answer the question: If cells are so numerous, why is cancer relatively uncommon?
From “How Daughter Cells Receive the Same Number of Chromosomes” (ScienceDaily, Nov. 1, 2011), we learn that scientists better understand now how cells ensure that daughter cells receive an equal number of chromosomes. An odd number is implicated in the development of cancer:
Most cells in our bodies contain 23 pairs of chromosomes that encode our individual genetic identities. In healthy, dividing human cells, each of these chromosomes is duplicated and one copy passed to each of the two daughter cells. However, if this process is disturbed, daughter cells receive an unequal number of chromosomes, a state that is known to drive normal cells to become cancerous. In fact, aggressive human tumours are frequently composed of cells with an abnormal complement of chromosomes.
Professor Jonathan Millar explained: “This cell division process is monitored by the body’s surveillance system known as the ‘spindle checkpoint’, and that is only switched off once everything within the cell is set up correctly. Amazingly, all of the elements of this process are conserved from yeast to human cells.
“Amazingly” crops up as often in cell biology these days as “groovy” used to among hippies.
“Therefore it is extremely likely that what we have found in yeast also happens in human cells. So by preventing this process happening with drugs, you could restrict the cell’s ability to develop into full blown cancer,” explained Professor Millar.