Cell Reproduction and Heredity USV: Mitosis and Meiosis Ask them to get down the 5 phases and what happens in each.

How do little elephants grow up to be BIG elephants?

Why do animals shed their skin?

Three reasons why cells reproduce by asexual reproduction: Growth 2. Repair 3. Replacement

Animated Mitosis Cycle http://www.cellsalive.com/mitosis.htm Interphase Prophase Metaphase Anaphase Telophase & Cytokinesis http://prezi.com/6dcz8acgjysx/mitosis/

Animal Mitosis -- Review Interphase                                                              Prophase                                                              Metaphase                                                              Anaphase                                                              Telophase                                                             

Plant Mitosis -- Review Interphase                                                              Prophase                                                              Metaphase                                                              Anaphase                                                              Telophase                                                             

Plant vs. Animal ANIMAL Cell membrane pinches apart Has centrioles Rigid cell walls do not pinch apart Cell plate forms between 2 new nuclei No centrioles

Asexual Reproduction Organisms produced from one parent like mitosis FISSION = division of organism into parts (bacteria) Body cells do this

Asexual Reproduction REGENERATION = whole organism may develop from piece of organism or when organism is injured (sponges, planaria, sea stars) BUDDING = organism grows from body of parent (hydra)

Meiosis 46 Sexual Reproduction = new organism produced when sex cells from 2 parents combine Sperm and Egg cell (104) Meiosis = process of nuclear division that produces sex cells in the reproductive organs 46 46 23 23 23 23 46 46 46 23 23 23 23

Meiosis Human cells have 23 pairs of chromosomes 46 total Sex cells have 23 chromosomes Why?? Diploid = cell that has 2 of every kind of chromosome Haploid = Sex cell with 1 chromosome from each pair

Meiosis Fertilization = joining of egg and sperm 23 46 23 Fertilization = joining of egg and sperm Zygote = cell that forms during fertilization The zygote will then undergo mitosis to develop Picture handout

Meiosis l & ll Please look at your handout What do you see happening? Begins with 1 cell Meiosis l forms 2 cells Meiosis ll results in 4 cells

Differences Mitosis Meiosis 2 nuclear divisions 1 nuclear division Chromosomes line up in pairs ½ number of chromosomes 4 cells Crossing over during Prophase I Mitosis 1 nuclear division Chromosomes line up singly Same # of chromosomes 2 cells No crossing over