CAS CH 203 Lecture Notes - Lecture 13: Hemiacetal, Carbohydrate Metabolism, Aldehyde
Document Summary
Lecture 13 introduction to sugar chemistry and polymers of sugars: we have already discussed the chemistry of carbonyls (aldehydes and ketones). We will see in glycolysis, gluconeogenesis and the pentose phosphate pathway that there are two variations on the carbonyl transformations that are essential to understand in carbohydrate metabolism. C and d. introduction to glucose and polymers of glucose (cellulose and glycogen: inside the cell, most sugars are present as phosphate monoesters. Phosphate is largely a dianion and it keeps the sugar from diffusing out of the cell: carbonyl addition reactions (think electrophile and nucleophile) Addition of roh to form a hemiacetal or hemiketal. Hemiacetals at ph 7. 4 are in rapid equilibrium inside the cell. Ketals (r1/r2) and acetals (r1/h) can be generated chemically starting with a ketone or aldehyde in the presence of an excess of alcohol (roh) and an acid catalyst, h+.
