Understanding Mitosis and Its Importance

Overview

• Purpose of Video: By the end of this lecture, you should be able to:
  • Describe the importance of mitosis.
  • Describe the stages of the cell cycle involving mitosis.

Key Concepts

• Nucleus and Chromosomes:

  • Both plant and animal cells contain a nucleus.
  • The nucleus contains chromosomes made of DNA.
  • Example cell shown has 4 chromosomes.
  • Body cells have paired chromosomes (e.g., human cells have 23 pairs).
  • Gametes have unpaired chromosomes (will be covered later).

• Chromosomes and Genes:

  • Chromosomes carry a large number of genes determining features.
  • Example chromosomes shown with 4 genes but usually, they have hundreds.

The Cell Cycle

• Necessity of Cell Division:

  • Animals and plants have many cells, necessitating division.
  • Cells can divide by mitosis or meiosis (meiosis covered later).

• Stages of the Cell Cycle (Involving Mitosis):

  • Stage 1:
    • DNA replication occurs, forming two copies of each chromosome that stay attached.
    • Cell grows and copies internal structures (mitochondria, ribosomes).
  • Stage 2 (Mitosis):
    • One set of chromosomes pulled to each end of the cell.
    • Nucleus divides.
  • Stage 3:
    • Cytoplasm and cell membrane divide.
    • Result: Two identical cells, each with the same number of chromosome pairs as the original.

Functions of Mitosis

• Growth and Development:
  • Essential for the growth and development of multicellular organisms (e.g., plants and animals).
• Repair:
  • Occurs when organisms repair themselves (e.g., healing of a broken bone).
• Asexual Reproduction:
  • Mitosis is involved in asexual reproduction (will be covered later).

Additional Resources

• Revision Workbook:
  • Contains practice questions on the cell cycle and mitosis.
  • Available through a provided link.

Conclusion:

• You should now be able to explain the importance and stages of mitosis in the cell cycle.