CELLULAR REPRODUCTION

• How did I grow taller?• How are my worn out cells replaced? • How do I heal from injuries?

• The answer is….Cellular Reproduction or Mitosis

THE CELL CYCLE:

• Cells go through cycles during their lifetime.

• Cells spend MOST of their time in a stage of growth and development called Interphase

 Interphase

Cells grow in size and number of organelles. This is the Growth and Development stage.

  

Chromosome Replication

 Cell Reproduction (Mitosis)

 

  Prepare for cell reproduction (Mitosis)

MITOSIS

1. Type of cell division when chromosomes are duplicated and then separate into two identical and complete sets to be passed to each of the two daughter cells.

2. In this type of cell division, the hereditary information is identical in all the cells that result.

3. Responsible for growth, maintenance and repair.

4. In some one-celled organisms, asexual reproduction is achieved through mitosis.

5. Cancers are a result of abnormal cell division.

MEIOSIS

1. Responsible for producing egg and sperm 2. The resulting daughter cells contain one-half the hereditary information.

KEY WORDS

Cell membrane: Controls what enters and leaves the cell

Nuclear membrane: Controls what enters and leaves the nucleus

Chromosomes: Contains the DNA

Centromere: Holds the Chromosomes together

Centriols: Pulls the chromosomes apart

STEPS OF MITOSIS:

• During Interphase, chromosomes are copied (the number doubles). Chromosomes appear as threadlike coils (chromatin) at the start, but each chromosome and its copy change to sister chromatids at the end of this phase.

• During Prophase, nuclear membrane breaks apart. Centrioles begin to move to opposite ends of the cell. Spindle fibers form between the centrioles (at the poles of the cell).

Diagrams of Interphase and the start of Mitosis: Prophase

Diagrams of Metaphase, Anaphase, Telophase (the final stage of Mitosis), and Cytokinesis

During Metaphase chromosomes line up at the middle of the cell and attach to the spindle fibers.

During Anaphase chromosomes are separated and are pulled to the opposite sides of the cell.

During Telophase, nuclear membrane reforms around two sets of chromosomes. Mitosis ends.

Final stage of the cell cycle is Cytokinesis, or the splitting of two cells. Each new cell has its own nucleus with identical chromosomes.

 In animal cells, the cell membrane moves inward and pinches together.

In plant cells, a cell plate forms from the center outward until a cell wall is made.

DIAGRAMS OF MITOSIS

 RESULT OF A MITOSIS DIVISION:

• Number of chromosomes in each of the two resulting daughter cells is the same as the amount of chromosomes in the original parent cell.

• For example: In fruit flies the parent cell has 8 chromosomes. After mitosis, each new daughter cell has 8 chromosomes.