Cell Growth and Reproduction: MITOSIS Objectives: A. List the purpose of cell division B. Diagram the cell cycle C. Explain the structure and purpose of chromosomes D. Sketch and explain the steps of mitosis E. Describe on a basic cellular level the cause of cancer

If we are all made up of cells…. How do little elephants grow up to be BIG elephants? A.List the purpose of cell division

How is it possible for animals to shed their skin? A.List the purpose of cell division

Cells Divide and multiply constantly!! A.List the purpose of cell division

Why do cells divide? Growth A.List the purpose of cell division Repair Replacement We shed old skin cells constantly

Why do cells divide? Cells divide CONSTANTLY!! As organisms grow and change, worn out tissues are repaired or replaced by newly produced cells. A.List the purpose of cell division

The Cell Cycle The cell cycle is the sequence of growth and division of a cell. The growth period is called INTERPHASE. During interphase the cell:  Grows  Carries on basic life processes  Makes copies of DNA for cell division The division period is called MITOSIS. B. Diagram the cell cycle

The Cell Cycle – A quick Review Interphase  G1—Cell is growing  S – DNA replicates  G2 – Prepares for division Mitosis  Prophase  Metaphase  Anaphase  Telophase B. Diagram the cell cycle

Chromosomes Chromosomes are cell structures that carry genetic material. They contain DNA. Chromosomes are always present in cells. The genetic material is passed from generation to generation. C. Explain the structure and purpose of chromosomes

The structure of chromosomes During most of the cells life, chromosomes exist as chromatin, which are strands of DNA. In what cell organelle is this found? THE NUCLEUS! As the cell begins to divide the chromatin coils forming short, thick chromosomes. Each chromosome is made up of two halves called sister chromatids. They are exact copies of each other. The sister chromatids are held together by a centromere. C. Explain the structure and purpose of chromosomes

The Structure of Chromosomes centromere Double Chromosome (sister chromatids) chromosome C. Explain the structure and purpose of chromosomes

Mitosis Interphase Prophase Metaphase Anaphase Telophase & Cytokinesis D. Sketch and explain the steps of mitosis

Interphase Stage of GROWTH before mitosis begins Chromosomes are copied (# doubles) Chromosome copies are called Sister Chromatids CELL MEMBRANE Nucleus Cytoplasm D. Sketch and explain the steps of mitosis

Interphase Animal Cell Plant Cell Photographs from: D. Sketch and explain the steps of mitosis

Prophase 1 st step in Mitosis Centrioles (or poles) appear and begin to move to opposite end of the cell. Spindle fibers form between the poles. Centrioles Sister chromatids Spindle fibers D. Sketch and explain the steps of mitosis

Prophase Animal Cell Plant Cell Photographs from: Spindle fibers Centrioles D. Sketch and explain the steps of mitosis

Metaphase 2 nd step in Mitosis Chromatids (or pairs of chromosomes) attach to the spindle fibers. Chromosomes line up in the MIDDLE Centrioles Spindle fibers D. Sketch and explain the steps of mitosis Metaphase=Middle

Metaphase Animal Cell Plant Cell Photographs from: D. Sketch and explain the steps of mitosis

Anaphase 3 rd step in Mitosis Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell. Centrioles Spindle fibers D. Sketch and explain the steps of mitosis Anaphase = Apart

Anaphase Animal Cell Plant Cell Photographs from: D. Sketch and explain the steps of mitosis

Telophase 4th s tep in Mitosis Two new nuclei form. Mitosis ends. Nuclei Chromatin D. Sketch and explain the steps of mitosis

Telophase Animal Cell Plant Cell Photographs from: D. Sketch and explain the steps of mitosis

Telophase completes with: Cytokinesis Cell membrane pinches together to create two daughter cells – each with its own nucleus with identical chromosomes. D. Sketch and explain the steps of mitosis

Animal Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Interphase D. Sketch and explain the steps of mitosis

Plant Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Interphase D. Sketch and explain the steps of mitosis

27 Cell Cycle

What are the leading causes of death in the United States? 1- Heart Disease 2- Cancer 3- Stroke 4- Accidents, Alzheimer’s, Diabetes E. Describe on a basic cellular level the cause of cancer

What is Cancer? Cancer: Uncontrolled cell growth creating a malignant tumor AKA: Mitosis out of control

Mutation Occasionally a cell is mutated The mutated cell will continue to divide and multiply into what could be cancer.

Mutation What INCREASES chances of cell mutation?  Radiation  Carcinogens (drugs, nicotine, alcohol, etc)  UV rays  etc

Bell Quiz 1. What is the process called when cells divide? 2. Why do cells need to divide? 3. Name the stages of Mitosis in ORDER 4. What is cytokinesis? Which stage of mitosis does it occur during? 5. What is the similarity of a cell from it’s daughter cell?

Bell Quiz Draw & Label the process of mitosis

The first phase – Prophase During prophase the long and stringy chromatin coils up to visible chromosomes. The nuclear membrane disappears. Centrioles move to opposite ends of the cell and the spindle begins to form between them. D. Sketch and explain the steps of mitosis

The second phase – Metaphase Metaphase is when the chromosomes become attached to the spindle fibers. They line up in the middle of the cell.

The third phase – Anaphase During anaphase the centromeres split apart and chromatid pairs from each chromosome split apart from each other. Each chromatid is now a separate chromosome.

The fourth phase – Telophase Telophase begins as the chromatids reach the opposite ends of the cell. The cytoplasm divides, the nucleolus and nucleus reappear and the chromosomes begin to uncoil. The cell is now ready to start the cell cycle again with interphase.

The division of the cytoplasm Towards the end of telophase the cytoplasm divides. (CYTOKINESIS) This happens differently in animal and plant cells.  In animal cells the plasma membrane pinches in.  In plant cells a cell plate forms across the cell’s equator. DIVISION IS NOW COMPLETE!