BIOC 503 - Carbohydrates

energy

carbohydrates is a family of molecules that provide ___ as well as ___ storage

• they are also part of the extracellular matrix, play an important role in cell signaling, and immune function

monosaccharide

single sugar unit

oligosaccharides

several sugar units 

polysaccharides 

large sugar chain made of many sugar units

aldose

sugar with an aldehyde group at the end of the chain

ketose

sugar with a ketone in the chain

triose

3 carbons sugar

tetrose

4 carbons sugar

pentose

5 carbons sugar

hexose

6 carbons sugar

heptose

7 carbons sugar

D

All sugars used by the human body are the __ enantiomers

hemiacetal linkages

monosaccharides can exist in cyclic forms by reaction C1 with the hydroxyl group in C5 to generate ____

anomeric carbon

carbon that bears the aldehyde or ketone in the cyclic form of sugar

anomers

the different stereoisomers of cyclic sugars

alpha anomer

OH group is UNDER the ring

beta anomer

OH group is OVER the ring

mutarotation

conversion between anomers

pyranose

6-atoms sugar rings

furanose

5-atoms sugar ring

chair conformation

conformation taken by cyclic sugars due to repulsion between adjacent groups preventing the molecule from being planar

alpha 1-4

disaccharides are usually formed by ____ linkages between the hemiacetal and alcohol of 2 sugar units

• form by condensation reaction and release water in the process

lactase

only digestive beta-galactosidase in humans, aka the only enzyme in humans able to break down beta-linkages

• digest milk sugar lactose

lactose

milk sugar that has beta 1-4 linkages, meaning that the link portion is on top of the plane

• only able to be broken by lactase in humans

lactose intolerance

• lack of lactase, leading to intestinal bacteria eating lactose, creating gas and lactic acid, which draws in water into the intestine making people lose fluid and experience serious diarrhea

homopolysaccharides

polysaccharides made of the same monomer, can be branched or unbranched

• starch

• glycogen

heteropolysaccharides

polysaccharides made of different monomers, can be branches or unbranched

• glycosaminoglycans (important components of ECM)

starch

amylose and amylopectin

branched

alpha 1-6

branched polysaccharides can branch off using ___ linkages

glycoconjugates

groups of carbohydrates that are covalently joined to other chemical species like proteins, lipids, etc.

• proteoglycans

• glycoproteins

• glycolipids

proteoglycans

glycosaminoglycan linked to core proteins

Crucial role in:

• tissue organization

• cell and tissue development

• mediate growth factor activity (proteoglycans trap growth factors in EMC)

• cell interactions

hyaluronan, chondroitin sulfate, keratan sulfate

Proteoglycans aggregate in EMC as their central ___ has multiple aggrecan branches made of covalently linked ___ and ___ making the molecule very hydrophilic

cellulose

humans cannot digest ___ due to its beta 1-4 linkages

cell signaling

proteoglycans and glycolipids are anchored in cell membrane and help with ____

glycoproteins

• different oligosaccharide linkages in ___ on red blood cells help characterize the different blood types

• also useful for white blood cell movements as blood vessels have a ___ that binds integrins on leukocytes, & leukocytes have a ___ that binds to P-selectin on blood vessels, both of which leads to a rolling movement

• also make up viruses’ spikes which is what is recognized by immune system