Question

Which of the following data were available to Watson and Crick when they were trying to determine the structure of DNA? Check all that apply. DNA is composed of 3 basic components: five-carbon sugars, phosphate groups, and 4 different nitrogenous bases. All DNA molecules have the same proportions of adenine, guanine, cytosine, and thymine. In DNA, the proportion of adenine always equals that of thymine, and the proportion of guanine always equals that of cytosine. X-ray diffraction patterns indicate that the DNA molecule has the shape of a helix. The DNA molecule is composed of 2 polynucleotide chains that are held together by hydrogen bonds between the nitrogenous bases. The replication of DNA is semi conservative. DNA always has an equal proportion of purines and pyrimidines. During DNA replication, synthesis of the leading strand is continuous and synthesis of the lagging strand is discontinuous. The 2 strands of DNA are antiparallel

Answer 1

Watson and Crick knew that DNA was composed of nucleotide components with purines and pyrimidines in equal proportion and that adenine pairs with thymine and guanine pairs with cytosine. They also utilized X-ray diffraction data which suggested DNA's helical shape, and deduced that DNA strands are antiparallel.

Step-by-step explanation:

When James Watson and Francis Crick were determining the structure of DNA, they had several pieces of data available. These included the facts that DNA is composed of three basic components: five-carbon sugars, phosphate groups, and four different nitrogenous bases. Additionally, they knew that in DNA, the proportion of adenine always equals that of thymine, and the proportion of guanine always equals that of cytosine, and that DNA always has an equal proportion of purines and pyrimidines. Crucial data came from Rosalind Franklin's X-ray diffraction patterns, which indicated the DNA molecule has the shape of a helix. However, Watson and Crick did not have direct evidence that the DNA molecule is composed of two polynucleotide chains held together by hydrogen bonds, the semi-conservative nature of DNA replication, or the specifics of leading and lagging strand synthesis during replication. They did correctly deduce that the two strands of DNA are antiparallel.