Question

question 12
a nucleotide is composed of ...
○ a nitrogenous base and a phosphate group.
○ a nitrogenous base and a pentose sugar.
○ a nitrogenous base, a phosphate group, and a pentose sugar.
○ a nitrogenous base, a phosphate group, a pentose sugar, and an amino acid.

Explanation:

To determine the correct composition of a nucleotide, we recall the structure of a nucleotide. A nucleotide, the building block of nucleic acids (DNA and RNA), consists of three components: a nitrogenous base (which can be purine or pyrimidine), a phosphate group, and a pentose sugar (deoxyribose in DNA, ribose in RNA).

• The first option is incorrect as it misses the pentose sugar.
• The second option is incorrect as it misses the phosphate group.
• The fourth option is incorrect because amino acids are the building blocks of proteins, not nucleotides.
• The third option correctly lists all three components of a nucleotide.

Answer:

C. a nitrogenous base, a phosphate group, and a pentose sugar.