Understanding the Fundamental Unit of Life

Aug 30, 2024

Fundamental Unit of Life

Discovery of the Cell

  • Cell: Fundamental unit of life.
  • Discovered by Robert Hooke in 1665.
    • Observed cork under a microscope.
    • Found box-like structures termed "cells" (meaning "little room").

Types of Organisms

  • Unicellular Organisms: Made of a single cell (e.g., bacteria, amoeba).
  • Multicellular Organisms: Made of many cells (e.g., plants, animals, humans).

Cell Theory

  1. All living organisms are composed of cells.
  2. The cell is the basic structural and functional unit of life.
  3. Cells arise from pre-existing cells (Rudolf Virchow).

Diversity of Cells

  • Multicellular organisms have different types of cells (e.g., muscle, nerve, blood cells).
  • Division of Labor: Different parts of the body perform specific jobs.

Structure of a Cell

  1. Cell Membrane (Plasma Membrane): Protects cell components, selectively permeable, allows diffusion and osmosis.
  2. Nucleus: Contains chromatin (DNA), controls cell functions, has nuclear pores.
  3. Cytoplasm: Semi-transparent fluid with organelles, site of biochemical reactions.

Exchange of Materials

  • Diffusion: Movement of molecules from higher to lower concentration.
  • Osmosis: Movement of water from lower solute concentration to higher through a semi-permeable membrane.
  • Active Transport: Energy-required transport of materials.

Cell Organelles

  • Endoplasmic Reticulum (ER):
    • Rough ER: Has ribosomes, produces proteins.
    • Smooth ER: Synthesizes lipids, detoxifies substances.
  • Golgi Apparatus: Modifies, packs, and dispatches proteins and lipids.
  • Lysosomes: Contains digestive enzymes, cleans waste, and can cause self-destruction ("suicidal bags").
  • Mitochondria: Powerhouse of the cell, produces ATP, has its own DNA.
  • Plastids (Plant cells only): Contains pigments, involved in photosynthesis.
  • Vacuoles: Storage sacs for materials, larger in plant cells.

Cell Division

  • Mitosis: Produces identical daughter cells for growth and repair.
  • Meiosis: Produces gametes with half the number of chromosomes for reproduction.
  • Chromosomes: Carries genetic material, involved in inheritance and cellular activities.

Importance of Cell Structures

  • Cell Wall (Plant cells only): Provides structural strength, made of cellulose.
  • Membrane-bound Organelles: Facilitate different biochemical processes within the cell.

Key Learnings

  • Cells are the building blocks of life.
  • Various cell types and organelles perform specific functions essential for life.
  • Understanding cellular structures and processes is crucial for comprehending biological functions.