1. Mitosis and Meiosis/ Genetics

2. Announcements * next week is the Embryology lab. * There is a quiz next week and as usual cover materials from this lab and the upcoming one. *home assignment for today will be posted on my web-page late today

3. Today *Mitosis *difference between animal and plant cells *Meiosis

4. Mitosis *it serves as a means of growths and repair in multicellular eukaryotes *it a common feature of a lot of tissues in the human body e.g. skin wounds heals by mitosis e.g. bone fractures heals by mitosis e.g. Liver tissue can regenerate ? Brain cells ? Heart muscle cells(fibers) *uncontrolled cell division…benign or malignant tumors

5. Mitosis * Cell cycle *G1, S, and G2 are termed Interphase

6. Chromosomes Karyotype is numbers, forms and types of chromosomes in a cell

7. Mitotic phase 1-Prophase Chromatin in the nucleus condense. The nucleolus disappears. Centrioles begin moving to opposite ends of the cell and fibers extend from the centromeres. 2-Metaphase Spindle fibers align the chromosomes along the middle of the cell nucleus. This line is referred to as the metaphase plateor equator

8. Mitotic phase 3-Anaphase The paired chromosomes separate at the kinetochores and move to opposite sides of the cell. 4-Telophase Chromatids arrive at opposite poles of cell, and new membranes form around the daughter nuclei. The chromosomes disperse and are no longer visible under the light microscope.

9. Animal vs Plant cells *karyokinesis is the same *cytokinesis (cytoplasm division) -in animal cells, it is a function of the actin filaments of the spindle fiber. -in plant cells, it is a function of the cell wall

10. Mitosis * In brief, -one round of cell division per round of DNA synthesis. -one cell end with two cells of the same genetic content(2N)

11. Meiosis *it serves as a means of reproduction *two rounds of cell division per one round of DNA synthesis. *one cell with 2N content end with 4 cells of 1N content. *2 stages, Meiosis 1 and 2 *homologous recombination (synapse) occur between homologous pair of chromosomes. *in anaphase of meiosis one, the two sister chromatids remain attached and the whole chromosome is pulled toward one end

12. I got the picture *examine demo -Onion root tip mitosis -chiasmata(recombination or crossing-over) in meiotic cells of grasshopper *simulating mitosis and meiosis

13. The genetic disease project *group project *I will demonstrate how to use library resources *two weeks from today you will present for the class -PowerPoint presentation (15-20m’) -all the group members must share in the oral presenatation and written report