The backbone of dna and rna is composed . dna is double stranded due to interactions between adenine, cytosine, guanine, and thymine, which . uracil is .

The first gap is phosphate sugar skeleton

The second gap is  nitrogenous bases .

The third gap is  nitrogenous base too, found only in RNA.

The skeleton of DNA is the phosphate-sugar succession of which each sugar bears a nitrogenous base.

Nitrogen bases are nitrogenous organic compounds present in nucleic acids in the form of nucleotides in which they are linked to a sugar.

The five main bases are adenine, cytosine, guanine, thymine and uracil.

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answer: b. nucleolus

explanation: nucleolus is a structure in the nucleus are ribosomes are made.

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-charlie

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the scientific method.