The two strands of a double helix model of $DNA$ are held together by hydrogen bonds between
sugar and phosphate groups.
sugar and nitrogenous bases.
phosphate groups and nitrogenous bases.
nitrogenous bases.
Purines of $DNA$ are represented by
Adjacent nucleotides in a polynucleotide chain are joined by
Information flow or central dogma of modern biology is
Genes are chemically
Which of the following is not correct