The following statements pertain to the development of the theory of the structure of DNA. Match the statement with the appropriate step (observation, hypothesis, experiment designed to test hypothesis) in the scientific method. a. DNA consists of two strands that wind around each other to form a helix. b. The sample of DNA has equal amounts of the bases A and T, and equal amounts of the bases C and G. c. Direct X-rays at a sample of crystallized DNA and analyze the diffraction pattern to determine structural information.
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a. DNA consists of two strands that wind around each other to form a helix. - Hypothesis
b. The sample of DNA has equal amounts of the bases A and T, and equal amounts of the bases C and G. - Observation
c. Direct X-rays at a sample of crystallized DNA and analyze the diffraction pattern to determine structural information. - Experiment designed to test hypothesis
The scientific method is an iterative process used to explore observations, answer questions, and acquire new knowledge. Here’s a more detailed breakdown of the steps that were applied in the development of the theory of the structure of DNA:
1. Observation: Scientists like Erwin Chargaff observed consistency in the ratio of nucleotide bases in DNA samples, specifically noting that the amount of adenine (A) was about equal to thymine (T), and the amount of cytosine (C) was about equal to guanine (G). These observations are crucial as they offer a foundation for formulating hypotheses.
2. Hypothesis: Given the observations, scientists formulated hypotheses about DNA's structure. James Watson and Francis Crick proposed that DNA consists of a double helix, with the strands winding around each other. They inferred this structural hypothesis based on available data, including Chargaff's rules and the work of other scientists.
3. Experimentation: To test their hypotheses about the structure of DNA, scientists like Rosalind Franklin and Maurice Wilkins performed X-ray diffraction experiments. By directing X-rays at crystallized DNA and analyzing the patterns it created, they could gather empirical evidence about the three-dimensional shape of the DNA molecule.
It is through these steps that the modern understanding of DNA's double helical structure was confirmed, which has been foundational to the field of genetics and molecular biology.