Concept explainers
The Historical Strands of Cell Biology. For each of the following events, deduce whether it belongs mainly to the cytological (C), biochemical (B), or genetic (G) strand in the historical development of cell biology.
(a) Köllicker describes “sarcosomes” (now called mitochondria) in muscle cells (1857).
(b) Hoppe–Seyler isolates the protein hemoglobin in crystalline form (1864).
(c) Haeckel postulates that the nucleus is responsible for heredity (1868).
(d) Ostwald proves that enzymes are catalysts (1893).
(e) Muller discovers that X-rays induce mutations (1927).
(f) Davson and Danielli postulate a model for the structure of cell membranes (1935).
(g) Beadle and Tatum formulate the one gene–one enzyme hypothesis (1940).
(h) Claude isolates the first mitochondrial fractions from rat liver (1940).
(i) Lipmann postulates the central importance of ATP in cellular energy transactions (1940).
(j) Avery, MacLeod, and McCarty demonstrate that bacterial transformation is attributable to DNA, not protein (1944).
(k) Palade, Porter, and Sjøstrand each develop techniques for fixing and sectioning biological tissue for electron microscopy (1952–1953).
(l) Lehninger demonstrates that oxidative phosphorylation depends for its immediate energy source on the transport of electrons in the mitochondrion (1957).
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