Cell Cycle

Cell Division Functions Reproduction Grow & Develop Renewal & Repair

Mitosis Division of somatic cells (body cells) -diploid (2n) diploid (2n) -asexual reproduction

Chromatin - DNA and protein complex Chromosome - condensed DNA Sister Chromatids - 2 identical copies of the chromosomes DNA held together by a centromere

Stages Interphase G 1 - growth S – replication of chromosomes G 2 - preparation for division

Prophase -chromatin condenses to chromosomes (sister chromatids) -nucleoli and nuclear membrane disappear -2 pairs of centrioles move to opposite poles -microtubules extend from centrioles and form asters

Metaphase -centromeres of each chromosomes align on the metaphase plate...equator / middle of a cell -spindle fibers attach to the centromeres

Anaphase -sister chromatids separate into chromosomes and move to opposite poles….apart

Telophase -microtubules continue to elongate the cell -daughter cell nuclei form -nuclear membrane reappears -chromosomes become less tightly coiled....chromatin -division of nucleus complete

Cytokinesis -divides cytoplasm....2 separate daughter cells -begins in late anaphase and finishes in telophase itosis.html hill.com/sites/ /student_view0/chapter2/animation__how_t he_cell_cycle_works.html sisisg/nukediv.html

Plant Mitosis -no centrioles -form cell plate...derived from vesicles carrying cell wall material

Prokaryotic Cell Division -binary fission -bacterial chromosomes are attached to plasma membrane and elongation of cell separates chromosomes. Read Fig evolution of mitosis

Regulation of Cell Cycle Cell cycle checkpoints – G 1, G 2 and M phases -G 1 – “restriction point” ….ok it will divide....not approved switches to G 0 *specialized nerves and muscles are in the G 0 phase and liver unless injury occurs

Regulatory proteins -G 1, G 2 protein kinases -protein kinases activate or inactivate other proteins by Phosphorylating them. *activated kinases are attached to a cyclin protein and called cyclin dependent kinases (Cdks) -MPF “G 2 checkpoint”– maturation promoting factor “M phase promoting factor” triggers movement into M phase mations/hires/a_cancer5_h.html

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Kinetochore - structure of proteins and specific sections of DNA at the centromere.