Biology 1: Cell Theory and Structure

Study Notes

Biology is the study of living organisms and their interactions with the environment.
Understanding basic concepts like cell theory is essential for grasping biological principles.

Cell theory comprises three core postulates:
- All living organisms are composed of one or more cells.
- The cell is the basic unit of life.
- All cells arise from pre-existing cells.

Francesco Redi's Experiment (1668):
- Conducted experiments with jars to refute spontaneous generation.
- Showed that maggots appeared only when flies had access to the meat, indicating the necessity of a source (flies) for life.
Lazzaro Spallanzani (1765):
- Boiled nutrient broths and sealed flasks.
- Demonstrated that no microorganisms grew in the sealed containers, suggesting life comes from the air, not spontaneous generation.

Hans and Zacharias Janssen (1590):
- Credited with inventing the first compound microscope.
- Used multiple lenses to enhance magnification of objects.
Robert Hooke (1665):
- Authored "Micrographia," documenting microscopic observations.
- Coined the term "cell" after examining cork tissue, marking a fundamental discovery in biology.
Antonie van Leeuwenhoek (1670s):
- Created high-quality simple microscopes, providing enhanced clarity.
- Discovered microorganisms, labeling them "animalcules," showcasing the diversity of microscopic life.

Electron Microscopes (1930s):
- Developed by Ernst Ruska, utilizing electron beams for imaging.
- Achieve much higher magnifications than traditional light microscopes, revolutionizing biological imaging.

Compound microscopes consist of multiple lenses to magnify the object.
Key components include the eyepiece, objective lenses, stage, and light source.
Understanding each part's function is crucial for effective use and observation in biological studies.