Same chapter3 marksDifficulty: Medium
State Chargaff's rules and what they told Watson and Crick.
Molecular Basis of Inheritance
3 marksDifficulty: Medium
State three features of the Watson-Crick model of DNA.
Original Khojo Papers practice question — not from a past board paper.
Answer
DNA is a double helix of two antiparallel polynucleotide chains wound round a common axis, with the sugar-phosphate backbones outside and the bases inside. The bases pair specifically, adenine with thymine by two hydrogen bonds and guanine with cytosine by three. The helix is right-handed, with about ten base pairs per turn and a pitch of 3.4 nm.
No citable source has been recorded for this record. Treat it as practice material, not as fact.
Explanation
The specific base pairing is what makes accurate replication possible.
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