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Chapter 4 Section 1 Cell Division and Mitosis. The Cell Cycle. “life cycle” of a cell series of events that takes place from one cell division to the next no set time for cycle- ranges from minutes to days
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Chapter 4 Section 1 Cell Division and Mitosis
The Cell Cycle • “life cycle” of a cell • series of events that takes place from one cell division to the next • no set time for cycle- ranges from minutes to days • not only used to make an organism, but also to replace parts in an organism such as skin, bone, blood, etc. Interphase • period of growth and development of most eukaryotic cells (cells with a nucleus) • some cells, such as nerve cells and some muscle cells are always in this phase
Process in which the nucleus divides to form 2 identical nuclei • 4 steps: • Prophase • Metaphase • Anaphase • Telophase Mitosis Chromosome - structure in the nucleus that contains heredity material - duplicated chromosome coiled tightly into 2 thickened identical strands Chromatid
Steps to Mitosis: 1. Prophase • pair of chromatids are fully visible • nucleolus and nuclear membrane disintegrate • centrioles move to opposite ends of cells • spindle fibers begin to spread across cell *** Plant cells do not have centrioles.*** 2. Metaphase • pairs of chromatids line up along the center of the cell • the centromere(center of the chromatid) attach to the spindle fibers, one on each side
3. Anaphase • centromeres divide and spindle fibers shorten • chromatids move to opposite ends of the cells • separated chromatids now called chromosomes 4. Telophase • spindle fibers disappear • chromosomes uncoil • new nucleus forms • animal cells- cell splits down the middle • plants cells- cell plate forms
Results of Mitosis: • Remember: • It is the division of the nucleus • produces 2 new nuclei that are identical to each other and the original cell • every cell in your body, except sex cells, have 46 chromosomes (23 pairs) • all of these cells have the same set of genetic material (skin, hair, blood, liver cells all have the same nucleus and the same 46 chromosomes
a new organism is made from one organism (one parent) • offspring will have heredity material identical to parent (clone) Asexual Reproduction • process bacteria uses to reproduce • bacteria contains no nucleus so it cannot divide by mitosis • copies the genetic material and then the cell splits Fission Budding • type of asexual reproduction • adult will create a bud, which once large enough will break away