Question

which statement best describes how watson and cricks model used other scientists work to create a model of dna
they used chargaffs rule to determine that it contains ribose sugar
they used franklins photo to determine that dna was a double helix
they used levenes work to determine the number of base pairs in each strand
they used nirenberg and mathers studies to determine that dna is made of nucleotides

Explanation:

• Option 1: Chargaff's rule was about base - pair ratios (\(A = T\) and \(G = C\)), not about ribose sugar. DNA has deoxyribose sugar.
• Option 2: Rosalind Franklin's X - ray diffraction photo (Photo 51) was crucial. The pattern in the photo suggested a helical structure, and the symmetry of the pattern indicated a double - helix.
• Option 3: Levene's work was mainly about the identification of nucleotides as the basic units of nucleic acids, not about the number of base pairs in each strand.
• Option 4: Nirenberg and Matthaei's studies were about the genetic code (relating RNA codons to amino acids), not about the fact that DNA is made of nucleotides.

Answer:

They used Franklin's photo to determine that DNA was a double helix.