Nucleotide

• Structure: Contains three parts: Phosphate group: One or more phosphate molecules. Sugar: A five-carbon sugar (deoxyribose in DNA or ribose in RNA). Nitrogenous base: One of four bases (adenine, thymine, cytosine, guanine in DNA; adenine, uracil, cytosine, guanine in RNA).
• Role: Nucleotides are the building blocks of DNA and RNA. They also involve energy transfer (like ATP) and cellular signaling.

Nucleoside

• Structure: Contains two parts:Sugar: A five-carbon sugar (deoxyribose in DNA or ribose in RNA). Nitrogenous base: One of the four bases (adenine, thymine, cytosine, guanine in DNA; adenine, uracil, cytosine, guanine in RNA).
• Role: Nucleosides are the precursors to nucleotides. They are important in some biological functions but do not include the phosphate group.

Key Difference

• Phosphate Group: Nucleotides have a phosphate group; nucleosides do not. This phosphate group is crucial for forming the backbone of DNA/RNA and for various cellular functions.