Theory_on_Living_Things_Cell_Theory.pptx

Theory_on_Living_Things_Cell_Theory.pptx

1. Theories on Living Things (Cell Theory) Understanding the foundation of life Presented by: [Your Name] Subject: Biology / Life Science

2. What are Living Things? - Living things are organisms that show characteristics of life such as: • Growth and development • Reproduction • Response to stimuli • Metabolism • Homeostasis

3. Early Beliefs About Life - Spontaneous Generation: Life arises from non-living matter. Example: Maggots from rotting meat. - Abiogenesis: Life originated naturally from simple organic compounds.

4. Disproving Spontaneous Generation Key Experiments: - Francesco Redi (1668): Maggots come from fly eggs. - Lazzaro Spallanzani (1765): Microorganisms come from other microorganisms. - Louis Pasteur (1861): Swan-neck flask experiment proved biogenesis.

5. The Beginning of Cell Theory Pioneers of Cell Theory: - Robert Hooke (1665): Discovered 'cells' in cork tissue. - Anton van Leeuwenhoek (1674): Observed living cells. - Matthias Schleiden (1838): All plants are made of cells. - Theodor Schwann (1839): All animals are made of cells. - Rudolf Virchow (1855): Cells come from pre-existing cells.

6. The Three Tenets of Cell Theory 1. All living things are composed of one or more cells. 2. The cell is the basic unit of structure and function in living organisms. 3. All cells come from pre-existing cells.

7. Importance of Cell Theory - Explains structure and function of all organisms. - Shows life shares a common building block. - Helps understand diseases, growth, and reproduction. - Foundation of modern biology.

8. Modern Additions to Cell Theory - Energy flow (metabolism and biochemistry) occurs in cells. - Cells contain hereditary information (DNA). - All cells have similar chemical composition. - The activity of an organism depends on its cells.

9. Summary - The Cell Theory is central to biology. - It explains how life is organized, grows, and reproduces. - From microscopic cells comes the vast diversity of life.

10. References - Campbell & Reece. Biology (Pearson Education) - Miller & Levine. Biology: The Living Science - Pasteur Institute Resources - Various educational sources