Pentoses are a type of simple sugar, or monosaccharide, that contain five carbon atoms. They play a crucial role in various biological processes, including the synthesis of nucleotides, which are the building blocks of DNA and RNA. Common examples of pentoses include ribose and xylose. These sugars can be found in many natural sources, such as fruits and vegetables. Pentoses are important for energy production and cellular metabolism, as they participate in the pentose phosphate pathway, a metabolic pathway that generates NADPH and ribose-5-phosphate for biosynthesis.