The following sentences describe the historical scientific process of determining the structure and function of DNA. Arrange the sentences in the correct chronological and logical order to form a coherent paragraph.
- 1First, in 1869, Friedrich Miescher isolated a substance he called 'nuclein' from the nuclei of white blood cells, though he did not yet know its genetic significance.
- 2Decades later, in 1944, Oswald Avery and his colleagues demonstrated that this substance—by then known as DNA—was indeed the carrier of hereditary information, not proteins as previously believed.
- 3Following this discovery, in 1950, Erwin Chargaff published his observation that the bases adenine and thymine exist in equal ratios, as do cytosine and guanine.
- 4Ultimately, in 1953, James Watson and Francis Crick used these clues along with X-ray diffraction images to construct their double-helix model.
Cevap
The correct sequence begins with Friedrich Miescher's 1869 isolation of nuclein, followed by Oswald Avery's 1944 proof of its genetic role, followed by Erwin Chargaff's 1950 discovery of base ratios, and concluding with Watson and Crick's 1953 double-helix model.
The logical sequence is defined by both dates and explicit transitions: the sequence starts in 1869 ('First'), transitions to 1944 ('Decades later'), connects to 1950 ('Following this discovery'), and concludes in 1953 ('Ultimately') with Watson and Crick's model which synthesized the earlier clues.
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Anahtar Kavram
Using sequential transitions and chronological markers to establish a logical narrative order.