Exploring the World of Cells

Aug 18, 2024

Lecture Notes: The Amazing World of Cells

Introduction

  • Exciting days in science classrooms
    • Examples: Earthworm dissection, owl pellet dissection, osmosis eggs, genetic experiments with fruit flies
    • Personal story of observing an amoeba in 9th grade science class:
      • Fascination with single-celled organisms
      • Reflection on human composition of billions of cells

Modern Cell Theory

  1. Smallest Living Unit
    • Cell is the smallest living unit in all organisms.
  2. Composition of Living Things
    • All living things are made of one or more cells (unicellular vs multicellular).
  3. Cell Division
    • All cells come from pre-existing cells.

Types of Cells

  • Prokaryotes vs. Eukaryotes
    • Prokaryotes: Bacteria and Archaea
      • No nucleus or membrane-bound organelles.
    • Eukaryotes: Plants, animals, fungi, protists
      • Have membrane-bound organelles and a nucleus.

Cell Structure and Functions

Cell Membrane

  • Selectively permeable; maintains homeostasis.

Cytoplasm

  • Jelly-like material surrounding internal structures; present in both prokaryotic and eukaryotic cells.
  • Contains a cytoskeleton for support and movement.

Ribosomes

  • Non-membrane bound organelles present in both cell types; responsible for protein synthesis.

Eukaryotic Organelles

Nucleus

  • Contains genetic material (DNA); controls cell activities.
  • Nucleolus: Produces ribosomes.

Endoplasmic Reticulum (ER)

  • Rough ER: Has ribosomes; involved in protein production and transport.
  • Smooth ER: Lacks ribosomes; involved in lipid production and detoxification.

Golgi Apparatus

  • Packaging center; modifies and sorts molecules for transport within/outside the cell.

Mitochondria

  • Powerhouse of the cell; generates ATP through cellular respiration (requires glucose and oxygen).

Differences between Animal and Plant Cells

  • Chloroplasts: Present in plant cells; conduct photosynthesis.
  • Vacuoles:
    • Plant cells: Large central vacuole.
    • Animal cells: Several smaller vacuoles.
  • Cell Wall: Present in plant cells for protection and maintenance of shape; absent in animal cells.

Summary of Protein Synthesis and Secretion

  1. Proteins are synthesized from DNA instructions in the nucleus.
  2. Ribosomes assemble proteins, often located on the Rough ER.
  3. Rough ER transports proteins in vesicles to the Golgi apparatus for sorting.
  4. Proteins tagged for secretion exit the cell via membrane vesicles.

Conclusion

  • Encouragement to explore more about cells and their organelles.
  • Reminder to stay curious!