Answer :
Watson and Crick concluded that a large purine molecule (adenine or guanine) always binds to a small pyrimidine molecule (thymine or cytosine), so the distance between the two DNA strands is always the same.
Describe the double helix model of DNA.
The discovery of the double helix, the twisted ladder structure of deoxyribonucleic acid (DNA), by James Watson and Francis Crick in 1953 was a milestone in the history of science and marked the emergence of modern molecular biology. That is concerned with genes control chemical processes within cells.
A double helix represents the appearance of double-stranded DNA. Double-stranded DNA consists of two linear strands that run opposite or antiparallel to each other and twist. Each strand of DNA within the double helix is a long linear molecule made up of small units called nucleotides that form a strand. Each chain has a backbone of alternating deoxyribose sugar and phosphate groups.
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