mitosis

Mitosis Overview

• Mitosis is a type of cell division that results in two daughter cells that are genetically identical to the parent cell.

Phases of Mitosis

1. Interphase

• Pre-mitotic phase

• Cell growth and replication of chromosomes

• Subphases: G1, S, G2

2. Prophase

• Chromatin condenses into visible chromosomes

• Sister chromatids are formed and joined at the centromere

• Centrioles move to opposite poles of the cell

• The mitotic spindle begins to form

• Nucleolus disappears, nuclear membrane breaks down

3. Prometaphase

• Spindle fibers attach to the centromeres, forming kinetochores

• Microtubules connect kinetochores to centrosomes

• Chromosomes begin their movement toward the cell equator

4. Metaphase

• Chromosomes align along the metaphase plate (equator)

• Spindle fibers coordinate their movement to ensure proper segregation of chromosomes

5. Anaphase

• Sister chromatids separate at kinetochores and are pulled apart to opposite poles

• Polar microtubules lengthen further separating the poles of the cell

6. Telophase

• Chromosomes reach opposite poles and start to de-condense into chromatin

• Daughter nuclei and nucleoli begin to reform

• Spindle fibers disperse

7. Cytokinesis

• Division of the cytoplasm to form two separate daughter cells

In Animals:

• Cleavage furrow forms due to contraction of actin microfilaments

• The constriction belt around the cell tightens until the cell splits

In Plants:

• A cell plate forms at the equator, vesicles from the Golgi apparatus fuse to create two membranes

• A new cell wall forms between the membranes

Asexual Reproduction

• Involves one parent and no sex cells

• Offspring produced by cell division are genetically identical to the parent

• Common in bacteria, plants, and some animals

Mitotic Chromosomes

• Duplicated chromosomes consist of two sister chromatids narrowed at the centromere, carrying identical copies of original DNA.

• Sister chromatids are homologous, meaning they carry the same genetic information.

Mitotic Spindle

• Cytoskeletal structure formed from microtubules that segregate chromosomes during cell division.

• Centrosomes function as microtubule organizing centers, facilitating the formation of the spindle apparatus.