Issues of Mitosis “The Life and Times of the Cell”

Summary of Mitosis Mitosis Prophase: Replicated chromatin condense into chromatid pair Centrioles move to opposite poles Nuclear envelope disappears Spindle fibers start to form Metaphase Chromatid pairs line up at the equator Anaphase Chromatid pairs split Chromosomes are pulled to opposite poles by the spindle fibers Telophase Chromosomes de-condense into chromatin Nuclear envelope reappears Cytoplasm is divided into 2 cells Cytokenesis

One more Phase – GAP 0 (G0) Some cells do not replicate their centrioles during Prophase. They lose their ability to divide They enter the Gap 0 stage Neurons of the Spinal cord / Brain cells

Mitosis in Plant vs. Animal Cells The Rivalry Continues Plants have no centrioles but still form spindle fibers Plant cells divide from the inside out Cell Plate “Messy Metaphase”

Importance of Mitosis Method of reproduction for all single celled organisms Allows us to regenerate cells (tissue) repair cuts, bone breaks, etc Growth – one cell to trillions

How Long does the Cell Cycle Last? Pick up a textbook and turn to page 249. Read the section titled “Life Spans of Cells” and answer the 4 questions that follow.

Meiosis Special cell division that produces Haploid sex cells Consists of one replication and two cell divisions

Sexual vs. Asexual Asexual Reproduction Reproduction that doesn't involve sex cells Produces ‘clones’ of previous cells Ex: 1. Binary Fission 2. Fragmentation 2. Fragmentation 3. Budding 3. Budding Sexual Reproduction Reproduction involving sex cells Produces genetically different offspring Sperm + egg = Zygote (n) + (n) = (2n) (n) + (n) = (2n)

Cancer A disease of uncontrolled cell division Starts with a single cell that loses its control mechanisms due to a genetic mutation (mistakes in mechanisms due to a genetic mutation (mistakes in DNA replication) DNA replication) Can be caused naturally or by carcinogens (i.e.: tobacco smoke, chemicals, etc.) That cell starts dividing without limit, possibly killing the host (without treatment)

Cancer Treatment Three basic treatments: –Surgery to remove cancer –Radiation to kill affected cells –New drugs are becoming available (Chemotherapy) It is hard to remove cancer (tumors often lack clear boundaries) –Some tumors are very small and are found throughout the body (advanced stages) Radiation and chemotherapy are aimed at killing cancer cells –The body then has to replace those dead cells which requires a lot of energy –Therefore treatment must be balanced with overall patient health Unfortunately due to natural selection cancer that seems to have disappeared can come back in the future in a form that is resistant to the radiation / chemotherapy Using multiple drugs can decrease the risk of relapse –Multiple drugs decrease the probability of cells acquiring immunity

Types of Cancer Lung Cancer Breast Cancer Breast Cancer Brain Cancer Skin Cancer Skin Cancer Ovarian Cancer Uterine Cancer Cervical Cancer Cervical Cancer Testicular Cancer Kidney Cancer Prostate Cancer Prostate CancerLeukemia Eye Cancer Lymphatic Cancer Mouth Cancer Mouth Cancer Colon Cancer Pancreatic Cancer Bone Cancer Penile Cancer Penile Cancer

The cure is out there !