Cell Biology Overview

Significant Landmarks in Cell Discovery

• In 1667, Antonie van Leeuwenhoek first observed living cells, known as the "Father of Microbiology."
• He utilized single-lensed microscopes he designed himself to examine microbes, discovering bacteria and protozoa, which he called "animalcules."
• In 1833, Robert Brown identified the nucleus within cells, noting its presence in orchid tissues and describing stomata for gas exchange.
• Matthias Schleiden proposed in 1838 that all plants comprise independent, separate cells.
• In 1839, Theodor Schwann declared that all animal tissues consist of individual cells.
• Rudolf Virchow concluded in 1855 that cells arise only from pre-existing cells, reinforcing the continuity of life.

Cell Theory

• Developed primarily by Theodor Schwann and Matthias Schleiden, with contributions from Rudolf Virchow.
• Cell Theory principles include:
  • All living organisms are composed of one or more cells.
  • The cell is the fundamental structural and functional unit of life.
  • All cells originate from pre-existing cells through division.

Cell Diversity

• Cells, membrane-bound units filled with aqueous solutions, can replicate by growth and division.
• The cell is the simplest unit of life in the biological hierarchy.
• Organisms can be unicellular (e.g., Amoeba, Bacteria) or multicellular (e.g., Plants, Animals).
• Cells share basic functions such as energy use, environmental response, and reproduction; however, they exhibit diversity in size and shape.

Why Cells Are Small

• Small cell size enhances the efficiency of diffusion for nutrients and waste.
• Factors affecting diffusion include surface area, temperature, concentration gradient, and distance.
• A higher surface area to volume ratio in smaller cells facilitates better environmental interaction.
• Larger cells may struggle with material transfer, risking cellular function and viability—hence organisms favor small cells.

Basic Properties of Cells

• Cells are highly organized with a plasma membrane delineating content from the external environment, containing cytoplasm, sugars, amino acids, proteins, and organelles.
• Cell reproduction involves division, where genetic material is duplicated and equally distributed to daughter cells.
• Cells acquire and utilize energy, primarily from sunlight through photosynthesis in plants, converting light energy into chemical energy stored as carbohydrates.
• Animals consume these carbohydrates to derive glucose, which is vital for cellular energy supply.