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6th Grade Science / Lesson 11 - The Cell Cycle

Cell Cycle
What will we be learning today?


  • In this lesson, we are going to learn all about the cell cycle.


Are You Always Growing?


  • All organisms go through stages, or a life cycle. For example, animals are born, they grow and develop, and they die. Throughout an organism's life, cells are growing, dividing, and dying.

  • While you are growing, the cells of your body are growing and dividing at a greater rate than cells are wearing out. Your cells are increasing in number. No matter how large an organism grows, its cells remain the same size throughout its life. Your body cells are about the same size they were when you were a baby


  • Eventually you will be fully grown. Even then cells will still be growing and dividing--but more and more, they will be replacing worn-out cells. The number of cells in your body will not increase


  • The Cell Cycle


    • Every living cell is going through a cycle. The cell cycle is made up of a time of growth and a time of dividing. Most of a cell's cycle is spent growing and developing. This time is called interphase. During this time the cell prepares to divide.


    • When the cell divides, it is a continuous process--it does not stop and go. First, the nucleus of a cell divides into two identical nuclei.

    • The division of a nucleus into two during the process of cell division is called mitosis. Then gradually the cytoplasm divides, and the cell division is complete.



    • The cell life cycle is the sequence of growth and division in a cell.


    What Happens During Mitosis?


    • Mitosis is a continuous process. Who first observed cells in various stages of cell division? It was Walther Fleming, a German scientist. In 1879 he observed cells in various stages, or phases, of cell division by using a dye and drawing what he saw. He inferred this process by placing the pictures in sequence.


    Let's Review What We Learned Today!


    • Now complete your worksheet!