Pentoosisokerit

Pentoosisokerit, also known as pentoses, are a class of monosaccharides that contain five carbon atoms. Their chemical formula is C5H10O5. The most common pentoses are aldopentoses and ketopentoses, depending on the position of the carbonyl group. Aldopentoses contain an aldehyde group, while ketopentoses contain a ketone group.

The structure of pentoses consists of a linear carbon chain with a hydroxyl group on each carbon atom except for one, which is either an aldehyde or a ketone. In aqueous solution, pentoses can exist in both linear and cyclic forms, with the cyclic forms predominating. These cyclic forms, furanoses, are five-membered rings.

Ribose and deoxyribose are two well-known pentoses. Ribose is a crucial component of RNA (ribonucleic acid), ATP (adenosine triphosphate), and various coenzymes. Deoxyribose, which differs from ribose by the absence of an oxygen atom on the second carbon, is the sugar found in DNA (deoxyribonucleic acid). Other examples of pentoses include arabinose and xylose, which are found in plant cell walls as part of hemicellulose.

Pentoses play vital roles in biological systems, primarily as building blocks for nucleic acids and as components of energy-carrying molecules. They are also involved in metabolic pathways, such as the pentose phosphate pathway, which is important for generating reducing equivalents and producing pentose sugars for nucleotide synthesis.