Which molecule is a five-carbon sugar?

Ribose is classified as a five-carbon sugar, also known as a pentose. Sugars are categorized based on the number of carbon atoms in their structure, and pentoses specifically have five carbon atoms. Ribose plays a crucial role in the structure of RNA (ribonucleic acid), which is vital for protein synthesis and various cellular functions.

In contrast, glucose is a six-carbon sugar (hexose) that is central to cellular respiration. Galactose is also a six-carbon sugar and is an isomer of glucose, primarily involved in the formation of lactose in milk. Fructose, while notable as a fruit sugar, is also a six-carbon sugar that plays a role in energy metabolism. Understanding the distinctions among these sugars is important for grasping their different biological functions and pathways.