Carbohydrates

Major function/roles

- Energy source - Energy storage/reserves ex) plant: starch animal: glycogen and skeleton muscle - Structure/support ex) plant: cellulose animal: muco polysaccharides - Carbon skeleton for biosynthesis of other cellular components - Cellular recognition – cell surface interactions: glycoprotein

Definition

Polyhydroxy carbonyls & compounds that yield polyhydroxycarbonyls on hydrolysis. Usually include simple derivatives, i.e. sugar acids, amino sugars, phosphate ester (ex: glucose-1-phosphate)

Carbonyls

3 major classification of carbohydrates

1) Monosaccharides (=simple sugar)

2) Oligosaccharides: 2 or more (up to 10) monosacc joined by glycosidic bond, Monosacc and oligosacc often grouped together under the term – sugar 3) Polysacc: linear (cellulose) or branched (glycogen)

Monosacc

1) Aldose: if the carbonyl group is at end of C chain, the monosacc is an aldehyde and is called aldose 2) Ketose: if the carbonyl group is at any other position, the monosacc is ketone and is called ketose

#ing system

Isomerism

1) Ennatiomers = optical isomer = mirror image

If the OH group (farthest from the carbonyl) is written to the right, the sugar is D

2) Epimer Differ in the configuration at only 1 C atom

참고: Galactose: glucose와 결합하여 락토스(유당)이 됨

Cyclic form

The formation of pyranose rings in D-glucose is the result of rx between aldehyde and alcohol to form hemiacetals

Cyclic form

Any group to the right of C chain in the Fischer projection is written down

Monosaccharide derivatives

참고: 아세틸기 초산에서 OH기가 빠져나간 것

Disaccharides

Hemiacetal (hemiketal) can react with another mole of alcohol

Alcohol

Alcohol

산화의 역반응을 말한다. 일반적인 좁은 의미로는 수소가 가해지는 것 또는 산소를 주는 경우를 말하지만, 넓게는 전자를 얻었을 때 환원되었다고 한다. 하나의 반응으로 전자를 주는 것이 있으면 그 전자를 받아들이는 것이 반드시 있는 것으로 산화와 환원은 동시에 일어난다. I는 －1가 → 0가의 변화로 산화되고, C1은 0가 → －1가의 변화로 환원된 것으로 된다. 무기화학에서는 원자가가 낮게 된 경우를 말하고, 유기화학에서는 수소가 증가, 산소를 주는 경우를 환원이라 하고 특히 수소원자가 증가할 때를 수소화(hydrogenation)라고도 부른다. Aldehyde기, ketone기(유리 또는 헤미아세탈 결합)를 가지는 당은 Fehling액이나 Tollens시약을 환원하기 때문에 환원당이라고 한다. 유리 단당류는 전부 환원성을 보이기 때문에 환원당이다. [

Structure of Acetal

Glycosidic bond

Sucrose의 경우 Fructose는 알파와 베타 모두 2번탄소 즉, anomeric C이 알콜역할을 하므로 여분의 Anomeric C이 없으므로 Non-reducing sugar임

Polysaccharides = Glycans = Polyglycans

1) Homo polysaccharides = contain only a single type of monomer a) storage forms of monosaccharides that are used as fuels such as starch and glycogen b) serves as structural elements in plant cell walls and animal exoskeletons. Ex: Cellulose and chintin

Major homopolysacchairdes = starch, glycogen, cellulose, chitin

Amylopectin

2) Heteropolysaccs

a) Glycosaminoglycans = repeating disaccs of acetylglucosamine and uronic acid (usually glucuronic acid)

b) Bacterial cell wall = repeating disaccs of N-acetylglucosamine and N-acetyl muramic acid (Polysacc “backbone” crosslinked to peptide to form huge molecule called “peptidoglycan”