Science, Grade 6


Table Of Contents: Mitosis

1. The Cell Cycle

2.1. Life Cycle of a Cell
The life cycle of a cell is called the cell cycle.
2.2. What Is the Cell Cycle?
The cell cycle is a series of events that take place in a cell from one division to the next.
2.3. Two Steps of Cell Division
Cells divide in two steps – mitosis and cytokinesis (division of cytoplasm).
2.4. Mitosis and Cytokinesis
First, during mitosis the nucleus of the cell divides, and then during cytokinesis, the cytoplasm divides.

2. Chromosomes

3.1. Location of Chromosomes
The cell nucleus of most organisms contains chromosomes.
3.2. Chromosomes Contain Genes
Each chromosome is made up of thousands of different genes which contain the instructions for an organism’s traits.
3.3. Species and Chromosome Number
The number of chromosomes is unique for each species.

3. Pause and Interact

4.1. Review
Use the whiteboard tools to complete the activity.

4. Mitosis

5.1. Scientists Observe Mitosis
The process of mitosis has fascinated scientists since it was first observed through a microscope more than a century ago.
5.2. What Is Mitosis?
Mitosis is a duplication process of cells responsible for growth and development, as well as replacing worn out cells throughout our bodies.
5.3. Production of Identical Daughter Cells
The end result of mitosis is the production of two genetically identical “daughter cells” from a single “parent” cell.
5.4. Phases of Mitosis
The phases of mitosis include prophase, metaphase, anaphase and telophase.

5. Phases of Mitosis

6.1. Interphase
Interphase is the first stage of the cell cycle and the period before cell division. During this phase the cell matures and prepares to divide and copies its chromosomes (DNA) and centrioles. Note that centrioles are found only in animal cells.
6.2. Prophase
Each chromosome consists of two identical copies called chromatids. The chromosomes in the nucleus thicken and shorten and the two centrioles move to opposite ends of the cell. Between the centrioles, spindle fibers form at each side of the cell. The nuclear membrane breaks apart.
6.3. Metaphase
The double-stranded chromosomes line up along the center of the cell and the spindle fibers attach to each centromere.
6.4. Anaphase
The spindle fiber splits the centromere and the chromatids move to opposite sides of the cell.
6.5. Telophase
Nuclear membranes form around each of the two sets of chromatids. The spindle fibers break down and disappear. The chromosomes unwind and the nuclear membrane begins to form around the chromosomes.
6.6. Cytokinesis – Division of the Cytoplasm
Once mitosis is completed, the cytoplasm splits into two. During this stage, the animal cell membrane pinches in at the middle of the cell dividing it into two identical copies of the original cell called daughter cells. Each daughter cell gets half of the cell organelles and an identical set of chromosomes.

6. Comparing Plant and Animal Cell Mitosis

7.1. Mitosis in Plants
Plants use a similar process to divide with a few differences. For example, although a plant cell creates spindle fibers, it lacks centrioles.
7.2. Plants Form Cell Plates
Plant cells divide by forming a cell plate in the middle which grows until its edges reach the cell's outer surface splitting the parent cell into two daughter cells.

7. Pause and Interact

8.1. Review
Use the whiteboard tools to complete the activity.

8. Vocabulary Review

9.1. Vocabulary Matching Review

9. Virtual Investigation

10.1. Comparing Mitosis in Plant & Animal Cells
In this virtual lab investigation, you will study the process of mitosis using the images of prepared slides of onion root tip and early whitefish embryo. These images show dividing cells in various stages of mitosis.

10. Assessment

11.1. Mitosis