CARBOHYDRATES A carbohydrate is a biological molecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water); in other words, with the empirical formula C m (H 2 O) n (where m could be different from n). [1] Some exceptions exist; for example, deoxyribose , a sugar component of DNA , [2] has the empirical formula C 5 H 10 O 4 . [3] Carbohydrates are technically hydrates of carbon; [4] structurally it is more accurate to view them as polyhydroxy aldehydes and ketones . [5] The term is most common in biochemistry , where it is a synonym of sa...