Lecture Notes: Mitosis and the Cell Cycle

Overview of the Cell Cycle

• The cell cycle consists of a long period of growth and duplication, called Interphase, followed by Mitosis.

Interphase

• G1 Phase (Gap 1):

  • Cellular contents, excluding chromosomes, are duplicated.

• S Phase (DNA Synthesis):

  • Each of the 46 chromosomes is duplicated.

• G2 Phase (Gap 2):

  • Cell checks duplicated chromosomes for errors and makes necessary repairs.

Mitosis

• Results in two daughter nuclei with identical genetic material to the mother cell.

Stages of Mitosis

1. Prophase

   • Chromosomes condense and become visible.
   • Centrioles form and move to opposite poles.
   • Nuclear membrane dissolves.
   • Mitotic spindle forms.
   • Spindle fibers attach to each sister chromatid at the kinetochore.

2. Metaphase

   • Centrioles complete migration to poles.
   • Chromosomes line up at the cell equator.

3. Anaphase

   • Spindle fibers shorten, exerting force on sister chromatids to pull them apart.
   • Chromatids are pulled to opposite poles, ensuring identical chromosome sets in daughter cells.

4. Telophase

   • Chromosomes decondense.
   • Nuclear envelope reforms.

5. Cytokinesis

   • Division of the cytoplasm.
   • Completes the process of cell division to form two new daughter cells.

M-Phase

• Combination of mitosis and cytokinesis.

Vocabulary

• Centromere: Area where sister chromatids are held together.
• Chromatid: Each of a pair of identical DNA molecules post-DNA replication.
• Spindle Fibers: Attach to chromosomes and move them by pulling homologous chromosomes in opposite directions.
• Centrioles: Organelles that aid in spindle formation during cell division.
• Microtubules: Components of the cytoskeleton, mitotic spindle, cilia, and flagella.
• Kinetochores: Structure on the centromere where spindle fibers attach during mitosis and meiosis.

Practice Exercises

Practice I: Matching Phases/Stages

• Match the cell cycle phases with their corresponding activities.

Practice II: Diagram Labeling

• Label diagrams with stages such as Interphase, Cytokinesis, Telophase, etc.

Vocabulary Practice

• Understand and memorize the key terms associated with mitosis and the cell cycle.

References:

• Alberts, J. (n.d.)
• Michael, M. (n.d.)
• Mayo Clinic Staff. (n.d.)
• Various Online Resources