How do little elephants grow up to be BIG elephants? Objectives: 1. Review cell cycle 2. Describe the stages of mitosis 3. Explain why cells need to divide.

Why do animals shed their skin?

How do our bodies heal when we are injured?

THE CELL CYCLE: Throughout their lives, cells go through a continual process of controlled growth and division 3 main stages Interphase Mitosis Cell division or Cytokinesis

The process of mitosis begins after a sperm fertilizes an egg The process of mitosis begins after a sperm fertilizes an egg. This is how all of the somatic or body cells are formed - all cells, excluding the sex cells (sperm & eggs)

Mitosis allows cells or organisms to: Grow Repair damage to tissues and/or organs Replace dead or dying cells Cells that reproduce by asexual reproduction (mitosis) are able to reproduce constantly.

Skin cancer is the abnormally fast growth of skin cells – most often develops on skin exposed to the sun.

THE CELL CYCLE The greater portion of a cell’s life is spent in interphase “Inter” means between Growth and normal cell functioning occurs during interphase (i.e. heart cells work to pump blood during Interphase)

The cell cycle is a continuous process of: mitosis, cell division and interphase.

Animated Cell Cycle Interphase Prophase Metaphase Anaphase Telophase Cytokinesis Video Animation (Virtual Cell) https://youtu.be/C6hn3sA0ip0

Interphase occurs before mitosis begins Chromosomes are copied (# doubles) Chromosomes appear as threadlike coils (chromatin) at the start. Each chromosome and its copy = sister chromatids CELL MEMBRANE Nucleus Cytoplasm

Interphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Prophase 1st step in Mitosis Chromosomes are condensed and visible. Nuclear membrane starts to disappear. Centrioles appear and begin to move to opposite ends of the cell. Spindle fibers form between the poles. Centrioles Sister chromatids Spindle fibers

Prophase Plant Cell Animal Cell Spindle fibers Centrioles Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Metaphase 2nd step in Mitosis Sister Chromatids attach to the spindle fibers and line up along the equator of the cell. Centrioles Spindle fibers

Metaphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Anaphase 3rd step in Mitosis Sister Chromatids separate as the spindle fibres pull them. They begin to move to opposite ends of the cell. Centrioles Spindle fibers

Anaphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Telophase 4th step in Mitosis Two new nuclei form. Spindle fibres disappear. Chromosomes reappear as chromatin (threads rather than rods). Mitosis ends. Nuclei Nuclei Chromatin

Telophase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Cytokinesis occurs after mitosis Cell membrane moves inward to create two daughter cells – each with its own nucleus with identical chromosomes.

Animal Mitosis -- Review Interphase                                                              Prophase                                                              Metaphase                                                              Anaphase                                                              Telophase                                                             

Plant Mitosis -- Review Interphase                                                              Prophase                                                              Metaphase                                                              Anaphase                                                              Telophase                                                             

IPMATC REMEMBER! Interphase Prophase Metaphase Anaphase Telophase Cytokinesis IPMATC A mnemonic to help remember the stages of mitosis. Can you create an mnemonic to remember the stages of mitosis? 24

Cell Cycle 25

Music Time! Time for Mr. W!!! https://youtu.be/pOsAbTi9tHw