THE CELL THEORY

Cell Theory

  • Fundamental scientific theory in Biology

  • Proposes that cells are basic units of all living tissues

  • Proposed by Theodor Schwann and Matthias Jakob Schleiden in 1838

  • Marked a significant conceptual advance in biology

Key Principles of Cell Theory

  • Every living organism is composed of one or more cells

  • The cell is fundamental to life

  • Every cell arises from another cell (biogenesis)

  • Initial observation made by Robert Hooke in 1665 using a microscope, identifying cells in cork

Contributions of Early Scientists

  • Robert Hooke: first to describe cells, leading to the cell theory

  • Matthias Schleiden and Theodor Schwann (1839): formulated an early version of cell theory, stating:

    • All organisms are made of cells

    • Organisms can be unicellular (single cell) or multicellular (multiple cells with specialization)

Basics of Molecular Biology

  • Intersection of genetics, biochemistry, and physics

  • Focuses on understanding cell functions at the molecular level

  • Term "molecular biology" coined by Warren Weaver in 1938

  • Involves techniques for manipulating nucleic acids (DNA, RNA)

Evolution of Molecular Biology

  • Emerged in the 20th century with advancements in genetics and discovery of DNA as genetic material

Rosalind Franklin and DNA Structure

  • Contributed key insights into the double-helix structure of DNA through X-ray diffraction

  • Her work was underappreciated but was essential for Watson and Crick's DNA model in 1953

Advances in Molecular Biology and Genetics

  • Major discovery by Franklin paved the way for further developments

Cloning and Gene Therapy in the 20th Century

  • Cloning definition: reproducing organisms to obtain genetically identical beings

    • Can be applied to cells, animals, and plants

  • Molecular cloning: isolating DNA fragments and multiplying them via vectors

  • Dolly the Sheep: first mammal cloned from an adult somatic cell in 1996