Lecture Notes: Introduction to Cells

Overview

• Objective: Understand what cells are, their subcellular structures, and the differences between animal, plant, and bacterial cells.
• Goal: By the end of the lecture, be able to label cell parts and describe their functions.

What are Cells?

• Basic Building Blocks of Life:
  • Smallest unit that can replicate independently.
  • In multicellular organisms, cells divide for growth or replacing dead cells.
  • In unicellular organisms like bacteria, each cell constitutes an entire organism.
• Human Cells:
  • Humans contain hundreds of different types.
  • Estimated over 40 trillion cells in an adult human.

Cell Structure

Eukaryotic Cells: Animal vs. Plant Cells

• Common Structures:
  • Cell Membrane: Regulates entry and exit of substances.
  • Nucleus: Contains DNA; controls cell activities.
  • Cytoplasm: Gel-like substance where organelles sit and chemical reactions occur.
  • Mitochondria: Powerhouse of the cell; site of aerobic respiration.
  • Ribosomes: Site of protein synthesis.
• Additional Structures in Plant Cells:
  • Cell Wall: Rigid structure made of cellulose for support and protection.
  • Permanent Vacuole: Contains cell sap (mixture of sugars, salts, and water).
  • Chloroplasts: Site of photosynthesis; contain chlorophyll for light absorption.

Prokaryotic Cells: Bacterial Cells

• Structure:
  • Cell Membrane
  • Cell Wall
  • Ribosomes
  • Cytoplasm
• Key Differences:
  • No Mitochondria or Chloroplasts.
  • Genetic Material:
    • Free-floating circular DNA strand (nucleoid/circular chromosome).
    • Plasmids: Small rings of DNA carrying extra genes (e.g., antibiotic resistance).
  • Flagella: Thread-like structures for movement.

Conclusion

• Additional Resources: For practice questions, visit the revision site linked in the video.
• Reminder: Understand the structural differences and similarities among cell types.

Remember to review these notes regularly to reinforce understanding of cell structures and functions.