October 6, 2008 Lecture 9 – Cell Division: DNA • mitochondria, chloroplasts, and nuclei all have DNA in plants – 3 different genomes • prokaryotes have DNA but no nucleus/nuclear membranes Cell division in your life • most cells are not actively dividing • those that are, are in tissues that are constantly renewing, repairing, and growing (e.g. skin, blood, liver, intestinal lining Cell Division in Plants • primary growth in the roots of plants • secondary growth around the stem that allows the plant to grow out 3 reasons why cell division is important in biology: 1. Growth and development 2. Tissue renewal 3. Microbial population Stem Cells • Self renewing • A stem cell divides in two just like all other cells. Except that it doesn’t divide equally in two. One daughter cell remains a stem cell and the other goes on to do another job. As the second cell goes on to do its job, its potential to divide is dramatically reduced and it goes on to give rise to other sorts of cells. Cancer stem cells
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