liveonearth (liveonearth) wrote,
liveonearth
liveonearth

Biochemistry 315 & 316: Carbohydrates


Cn(H2O)m --- it's a hydrate of carbon, not a hydrocarbon
-some have wrong number of O's
-some have amines
-glucose C6(H2O)6 (monosaccharide)
-sucrose C12(H2O)11 (disaccharide)
-mono, di, oligo, polysaccharide
-mono: n=3 to 8
-ose suffice = carbohydrate (aldose, ketose)

Fx
-store energy (glucose, starch, glycogen)
-structure (cellulose, chitin)
-structural component of DNA/RNA to store genetic info
-cell identification (blood groups ABO, etc)

How does this differ from a hydrocarbon?
-hydrocarbons have hardly any O's
-burn better
-CnH2n or so

How are cyclic carbohydrates formed?
-sugar rings are formed of 4-6 carbon molecules, no less due to ring strain
-boat vs chair conformation: chair is less strained

What is a hemi-acetal?
-sugars are cyclic hemiacetals
-hemiacetal = aldehyde or ketone + alcohol forming 5 or 6 membered ring

What is an anomeric carbon?
-involved in ring closure, forming new stereocenter at C1
-a specific case of an epimer
-C1 is where polymers are formed, attach new monomer there
-if OH on free C1 is up it's a beta anomer, if OH is down it's alpha

Enantiomer?
-nonsuperimposable mirror image molecule
-optical activity = how stuff rotates a plane of polarized light
-R or S enantiomers
-carbon is attached to 4 different things

Diastereomer?
-non mirror image molecules, non superimposable
-multiple stereocenters

Epimer?
-all anomers are epimers, but not all epimers are anomers
-diastereomer differing at only 1 carbon (of several)

How do monosaccharides become di-, tri-, polysaccharides??
-attach new monosaccharide at C1
-form link between anomeric carbon of one plus hydroxyl of next
Tags: biochemistry, carbs, sugar
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