Key Concepts in Cell Biology

  • Hooke's Discovery (1665)

    • Robert Hooke used a microscope to study cork and discovered cells, which he compared to honeycomb.
    • Observed dead plant cells with only cell walls remaining.

  • Leeuwenhoek's Observations

    • Antonie van Leeuwenhoek invented microscopes with magnification up to x250.
    • First to observe living microorganisms, termed "animalcules".
    • Discovered human red blood cells and bacteria.

  • Cell Theory Development

    • Robert Brown (1833): Identified the nucleus in plant cells.
    • Matthias Schleiden (1838): Proposed plants are made of cells.
    • Theodor Schwann (1839): Extended cell concept to animals.
    • Karl Nägeli (1842): Observed cell division.
    • Rudolf Virchow (1855): Proposed all cells arise from existing cells.
    • Key points of Cell Theory:
    • All living things are made of cells.
    • Cells are the basic unit of life.
    • New cells originate from existing cells.

  • Cell Structure

    • Nucleus: Controls cell activities.
    • Cytoplasm: Gel-like substance where cell processes occur.
    • Cell Membrane: Regulates substances entering/leaving the cell.
    • Vacuole: Stores nutrients and waste; larger in plant cells.

  • Animal Cells

    • Composed of organelles like mitochondria (energy producers) and lysosomes (waste disposal).
    • Ribosomes produce proteins but are not membrane-bound.

  • Plant Cells

    • Similar to animal cells but with cell wall (for support), larger vacuoles, and chloroplasts (for photosynthesis).
    • Chloroplasts contain chlorophyll for converting sunlight into energy (creating glucose from CO2 and water).

  • Fungal Cells

    • Similar to animal cells but with a cell wall.
    • Cannot perform photosynthesis; absorb digested materials from their environment.

  • Unicellular Organisms

    • Made up of one cell (e.g., bacteria, protists).
    • Bacteria: Can be harmful or beneficial; essential in cheese and yogurt production.
    • Giardia: An infectious protist found in contaminated water.

  • Cell Division (Mitosis)

    • Process of a cell dividing into two identical cells, crucial for growth and repair in multicellular organisms.
    • Single-celled organisms also reproduce via mitosis.

  • Cell Types in the Body

    • About 50 trillion cells with various functions, including heartbeats and oxygen transport.