Biological Principles & Cell Biology
Cell biology forms the bedrock of life sciences, governed by the Cell Theory formulated by Theodor Schwann, Matthias Schleiden, and Rudolf Virchow, which asserts that all living organisms are composed of cells arising from pre-existing cells. Cells are categorized into prokaryotes, lacking membrane-bound nuclei, and eukaryotes, possessing specialized organelles like mitochondria (the cellular site of ATP synthesis through cellular respiration). Plant cells uniquely feature cellulose cell walls, large central vacuoles, and chloroplasts for photosynthesis. Genetic inheritance follows Gregor Mendel's laws of segregation and independent assortment, while Watson and Crick discovered the double-helix structure of deoxyribonucleic acid (DNA) in 1953 based on Rosalind Franklin's X-ray crystallography data.
Key Concepts & Examination Highlights
- Rudolf Virchow added the principle 'Omnis cellula e cellula' (all cells arise from pre-existing cells) to Cell Theory in 1855.
- Mitochondria produce adenosine triphosphate (ATP) through oxidative phosphorylation, functioning as the powerhouses of eukaryotic cells.
- James Watson and Francis Crick elucidated the double-helix model of DNA in 1953, drawing directly on X-ray diffraction images produced by Rosalind Franklin.