18 Questions
What is the angle between adjacent residues in the same chain according to the text?
36°
What is the distance of a phosphorus atom from the fiber axis according to the text?
10 Å
What is the structural feature of the DNA that allows cations easy access to the phosphates?
The structure is open
What is the novel feature of the DNA structure?
The pairing of adenine with thymine and guanine with cytosine
Which of the following is not mentioned in the text as contributing to the understanding of the DNA structure?
Pauling and Corey's work
What is the purpose of the fellowship from the National Foundation for Infantile Paralysis mentioned in the text?
To support the work of J.D. Watson
Which bases form a pair in the A Structure for Deoxyribose Nucleic Acid according to the text?
Adenine and Thymine
Which hydrogen bonds connect purine position 6 to pyrimidine position 6 in the DNA structure?
Two hydrogen bonds
What is the significance of considering tautomeric forms in the A Structure for Deoxyribose Nucleic Acid?
Ensuring proper base pairing
Which bases have novel features and are of considerable biological interest?
Cytosine and Guanine
How many inter-twined chains are present in the model proposed by Pauling and Corey for nucleic acid structure?
Three
What happens if an adenine forms one member of a pair according to the text?
It must pair with Thymine
What is the significance of the ratio of adenine to thymine and guanine to cytosine being close to unity for deoxyribose nucleic acid?
It suggests that the bases are paired in a specific manner, with adenine pairing with thymine and guanine pairing with cytosine.
What is the significance of the van der Waals distances appearing too small in the proposed structure?
It suggests that the structure is too compact and may not be stable.
Why is it considered unlikely to build the proposed structure with a ribose sugar instead of deoxyribose?
The presence of an extra oxygen atom in ribose would cause steric clashes with the bases.
What is the significance of the negatively charged phosphates near the axis of the proposed structure?
It indicates that the phosphates would repel each other, potentially destabilizing the structure.
What is the significance of the material that gives the X-ray diagrams being the salt, not the free acid?
It indicates that the acidic hydrogen atoms are not present in the structure being analyzed.
What is the authors' overall assessment of the proposed structure for deoxyribose nucleic acid?
It is roughly compatible with the available data but requires further confirmation from more exact results.
Test your knowledge on the pairing rules of DNA bases including purines, pyrimidines, and hydrogen bonding according to the A Structure for Deoxyribose Nucleic Acid model proposed in a Nature article from 1953.
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