Lecture Notes on Cells

Overview

• Focus on the structure and function of cells.
• Comparison between animal cells, plant cells, and bacterial cells.
• By the end, you should be able to label cell parts and describe their functions.

What are Cells?

• Basic building blocks of life.
• Smallest unit of life that can replicate independently.
• Multicellular Organisms: Animals and plants (e.g., humans).
  • Cells divide for growth and replacement, not as whole organisms.
• Unicellular Organisms: Bacteria.
  • Each bacterium is a whole organism that reproduces by division.

Structure of Cells

Common Features of Animal and Plant Cells

• Cell Membrane:
  • Controls substance passage in/out of the cell.
• Nucleus:
  • Contains genetic material (DNA) and controls cell activities.
• Cytoplasm:
  • Gel-like substance where organelles are suspended and chemical reactions occur.
• Mitochondria:
  • Provide energy through aerobic respiration (break down sugars).
• Ribosomes:
  • Site of protein synthesis (protein production).

Unique Features of Plant Cells

• Cell Wall:
  • Rigid structure made of cellulose providing support and structure.
• Permanent Vacuole:
  • Large sack containing cell sap (sugars, salts, water) for storage.
• Chloroplasts:
  • Site of photosynthesis, containing chlorophyll which absorbs light energy.

Bacterial Cells

• Prokaryotic, unicellular organism.
• Includes:
  • Cell Membrane: Similar to eukaryotic cells.
  • Cell Wall: Provides structure.
  • Ribosomes: Present for protein synthesis.
  • Cytoplasm: Contains organelles.
• Key Differences:
  • No mitochondria or chloroplasts.
  • Genetic material is a single circular strand of DNA (nucleoid).
  • May contain plasmids (extra DNA for antibiotic resistance).
  • May have flagella: Thread-like structures for movement.

Conclusion

• Summary of key points about cell types and their structures.
• Encouragement to visit the revision site for practice questions.