Biology: Chapter 9 - Mitosis

Cell Division

• We are able to physically grow because we create more cells.

• Too much cell growth can lead to cancer

• the process by which a parent cell divides into two daughter cells.

Why is cell division important?

1. Growth

2. Repair & regeneration (for other animals)

3. Reproduction in single-celled organisms

4. Replenishment

5. Reproduction (mitosis & meiosis)

Binary Fission

Aesexual reproduction where a parent cell divides, resulting into 2 identical cells. It happens in prokaryotes & single-celled eukaryotes.

Mitosis

• the process by which a cell replicates its chromosomes and then segregates them, producing two identical nuclei in preparation for cell division.

• 2 nuclei that result in identical to the original cell (Somatic cells)

Meiosis

• a type of cell division in sexually reproducing organisms that reduces the number of chromosomes in gametes.

• Results in 4 nuclei, each having half the number of chromosomes of the original cell (Sex cells)

Cell Cycle

• The process a cell goes through each time it divides.

Interphase

the phase of the cell cycle in which a typical cell spends most of its life, during this time it grows, replicates its chromosomes and prepares for cell division.

G1 Phase

• A time of major growth before DNA synthesis, it duplicates organelles and cytosolic components; and starts replicating centrosomes.

• the cell grows physically and increases the volume of both protein and organelles
  

S Phase

• The time during which DNA is replicated

• the cell copies its DNA to produce two sister chromatids and replicates its nucleosomes

G2 Phase

• A time of growth after DNA is synthesized before mitosis begins.

• involves further cell growth and organisation of cellular contents.

Parts of Mitosis

1. Prophase

2. Metaphase

3. Anaphase

4. Telophase

Prophase

• Long and thread-like chromatids during interphase start to coil, the nuclear membrane dissolves and spindle fibers are formed and centrosomes migrate at the opposite poles of the cell.

• the first phase of mitosis, the process that separates the duplicated genetic material carried in the nucleus of a parent cell into two identical daughter cells.

Metaphase

• Chromosomes move and align themselves at the center of the cell called metaphase plate. Spindle fibers connect each chromosome on its centromere to the centrioles located at opposite poles of the cell.

• individual chromosomes are spread out in the cell nucleus.

Anaphase

• The sister chromatids of each chromosome divide or split and move toward opposite poles due to shortening of the spindle fibers.

• the process that separates the duplicated genetic material carried in the nucleus of a parent cell into two identical daughter cells.

Telophase

• The chromosomes are located on opposite poles of the cell and the spindle fibers disappear. At the poles, the chromosomes uncoil and the nucleolus and nuclear membrane begin to reform.

• The process that separates the duplicated genetic material carried in the nucleus of a parent cell into two identical daughter cells.

Cytokinesis

the physical process of cell division, which divides the cytoplasm of a parental cell into two daughter cells.