BB ch7

Carbohydrate

A polyhydroxy aldehyde or ketone with the general formula (CH2O)n.

Monosaccharide

A simple sugar that cannot be hydrolyzed to smaller sugars under mild conditions.

Oligosaccharide

A carbohydrate composed of 2–10 monosaccharide residues linked by glycosidic bonds.

Polysaccharide

A polymer consisting of many monosaccharide units in linear or branched chains.

Aldose

A monosaccharide containing an aldehyde functional group.

Ketose

A monosaccharide containing a ketone functional group.

Triose

A three-carbon monosaccharide.

Tetrose

A four-carbon monosaccharide.

Chiral Center

A carbon atom bonded to four different substituents, giving rise to stereoisomerism.

Fischer Projection

A two-dimensional representation of stereochemistry used for carbohydrates and amino acids.

D/L System

Stereochemical notation that compares the configuration of a sugar’s reference carbon to D- or L-glyceraldehyde.

Glyceraldehyde

The simplest aldose; reference compound for assigning D or L configuration.

D-Glyceraldehyde

The enantiomer of glyceraldehyde whose chiral center matches the D configuration.

L-Glyceraldehyde

The enantiomer of glyceraldehyde whose configuration is the mirror image of D-glyceraldehyde.

Enantiomer

A pair of stereoisomers that are non-superimposable mirror images.

Epimer

A diastereomer that differs in configuration at exactly one chiral center.

Diastereomer

Stereoisomers that are not mirror images of each other.

Hemiacetal

The functional group formed when an aldehyde reacts intramolecularly with an alcohol.

Hemiketal

The functional group formed when a ketone reacts intramolecularly with an alcohol.

aldehyde

A class of organic compounds containing a carbonyl group (C=O) bonded to at least one hydrogen atom

alcohol

An organic compound with a hydroxyl group (-OH) attached to a carbon atom, often used as a solvent or as a precursor in chemical reactions.

acetal

A functional group formed when a hemiacetal reacts with an alcohol, resulting in two alkoxy groups attached to the same carbon.

ketone

A class of organic compounds characterized by a carbonyl group (C=O) bonded to two carbon atoms, often found in solvents and intermediates in organic synthesis.

Anomer

A stereoisomer differing in configuration only at the hemiacetal (anomeric) carbon. anomeric carbon is the c that is attached to 2 O atoms by single bonds

Mutarotation

Interconversion of α and β anomers in aqueous solution, reaching equilibrium. example: Reaction between the aldehyde group at C-1 and the hydroxyl group at C-5 forms a hemiacetal linkage, producing either of two stereoisomers, the α and β ANOMERS, which differ ONLY in the stereochemistry around the hemiacetal carbon.

Pyranose

A six-membered cyclic sugar form resembling pyran.

Furanose

A five-membered cyclic sugar form resembling furan.

D-Ribose

A five-carbon aldose that is a structural component of RNA.

2-Deoxy-D-ribose

A ribose lacking the 2′-hydroxyl group; component of DNA.

D-Glucose

A common hexose aldose; primary fuel for most organisms.

D-Mannose

An epimer of glucose differing at C-2.

D-Galactose

An epimer of glucose differing at C-4; component of lactose.

D-Fructose

A ketohexose found in fruit and honey; partner with glucose in sucrose.

Reducing Sugar

A carbohydrate that can reduce Cu2+ to Cu+ due to a free hemiacetal group.

Fehling’s Test

Analytical test using CuSO4/tartrate to detect reducing sugars via red Cu2O precipitate. test uses an alkaline Cu2+ solution

benedict’s test

A qualitative test that detects reducing sugars by producing a colored precipitate when heated with Benedict's reagent, which contains Cu2+ ions.

nonezymatic reaction of glucose w a primary amino group in hgb when sugar is high

hemoglobin→ schiff base → ketoamine → GHB → AGEs

Glycosidic Bond

An acetal linkage joining the anomeric carbon of one sugar to an alcohol or another sugar.

Maltose

A reducing disaccharide of two beta d-glucose units linked α(1→4). (non reducing sugar on left side, reducing sugar, hemiacetal, on right so maltose is reducing sugar)

Lactose

A reducing disaccharide of galactose β(1→4) glucose.

d-ketoses

dihydroxyacetone

d-erythrulose

d-ribulose

d-xylulose

d-fructose

d-psicose

d-sorbose

d-tagatose

Sucrose

A non-reducing disaccharide of glucose α(1→2) fructose β.

Amylose

The linear component of starch with α(1→4)-linked glucose residues.

Amylopectin

The branched component of starch with α(1→4) backbones and α(1→6) branches every 24–30 residues.

Glycogen

Animal storage polysaccharide with α(1→4) chains and α(1→6) branches every 8–12 residues.

Cellulose

A structural polysaccharide of β(1→4)-linked glucose forming rigid plant cell walls.

Chitin

A β(1→4) polymer of N-acetyl-D-glucosamine that forms exoskeletons of arthropods.

Dextran

A bacterial α(1→6)-linked glucose polymer with α(1→3) branches.

Peptidoglycan

Bacterial cell-wall heteropolymer of Mur2Ac-GlcNAc disaccharides cross-linked by peptides.

Agarose

Galactose-based heteropolysaccharide of algal cell walls used in electrophoresis gels.

Hyaluronan

A very large glycosaminoglycan of repeating GlcA-GlcNAc disaccharides; lubricant in joints.

Glycosaminoglycan

A linear, negatively charged heteropolysaccharide of repeating disaccharides containing amino sugars.

Heparin

Highly sulfated glycosaminoglycan that functions as a natural anticoagulant.

Hyaluronate

The salt form of hyaluronic acid; present in synovial fluid and vitreous humor.

Chondroitin Sulfate

A glycosaminoglycan found in cartilage and tendons, providing tensile strength.

Keratan Sulfate

A glycosaminoglycan abundant in cornea, cartilage, and bone.

Dermatan Sulfate

A glycosaminoglycan component of skin extracellular matrix.

Proteoglycan

A protein core covalently linked to one or more sulfated glycosaminoglycan chains.

Glypican

A GPI-anchored membrane proteoglycan with 14 conserved cysteines.

syndecan

A type of proteoglycan that is integral to the cell membrane and has multiple heparan sulfate or chondroitin sulfate chains.

Integrin

A membrane receptor that connects cells to extracellular matrix components including proteoglycans.

Fibronectin

An extracellular glycoprotein with binding sites for integrins and proteoglycans, mediating adhesion.

Glycoprotein

A protein covalently attached to oligosaccharide chains.

O-Linked Glycosylation

Attachment of sugars to the hydroxyl oxygen of Ser or Thr residues.

N-Linked Glycosylation

Attachment of sugars to the amide nitrogen of Asn within the consensus sequence Asn-X-Ser/Thr.

Glycolipid

A lipid molecule with covalently attached oligosaccharide; component of cell membranes.

Lipopolysaccharide (LPS)

Bacterial outer-membrane glycolipid containing lipid A, a core oligosaccharide, and an O-specific chain.

Lipid A

The hydrophobic, endotoxic anchor of bacterial lipopolysaccharide.

Endotoxin

Toxic component of Gram-negative bacteria, synonymous with lipid A of LPS.

O-Specific Chain

Variable polysaccharide region of LPS that determines bacterial antigenicity.

Lectin

A carbohydrate-binding protein that decodes sugar information in biological recognition.

Selectin

A cell-surface lectin that mediates leukocyte adhesion during inflammation.

Mannan-Binding Lectin

An innate immune lectin that recognizes high-mannose oligosaccharides on pathogens.

Concanavalin A

Plant lectin from jack-bean that specifically binds α-mannose residues.

Galectin-1

Animal lectin that binds β-galactosides and modulates cell–cell interactions.

Influenza Hemagglutinin

Viral lectin that binds sialic acid residues on host cell membranes.

Mannose 6-Phosphate Receptor

Lectin that targets lysosomal enzymes bearing mannose 6-phosphate for intracellular trafficking.

Hydrophobic Interaction (Sugar)

Non-polar stacking of sugar faces with aromatic residues in lectin binding sites.

Carbohydrate Recognition Domain

The portion of a lectin that directly contacts specific sugar residues.

Non-Reducing Sugar

A carbohydrate lacking a free hemiacetal, unable to reduce Cu2+ (e.g., sucrose).

D-aldoses

d-allose

d-altrose

d-gluocse

d-mannose

d-gulose

d-idose

d-galactose

d-talose

Branched Polysaccharide

A carbohydrate polymer containing side-chain branches such as glycogen or amylopectin.

Amylopectin Branch Frequency

Occurrence of α(1→6) branches approximately every 24–30 glucose residues.

Glycogen Branch Frequency

Occurrence of α(1→6) branches approximately every 8–12 glucose residues.

α(1→4) Linkage

Glycosidic bond connecting C-1 of one glucose to C-4 of the next in α configuration.

α(1→6) Linkage

Branch-forming glycosidic bond connecting C-1 of one glucose to C-6 of another in α configuration.

β(1→4) Linkage

Glycosidic bond connecting C-1 of one sugar to C-4 of another in β configuration (e.g., cellulose).

Enediol Rearrangement

Base-catalyzed tautomerization that converts ketoses to aldoses via an enediol intermediate.

Tautomerization

Chemical process where a compound interconverts between structural isomers, shifting a double bond and hydrogen.

Methylglyoxal

Reactive dicarbonyl formed non-enzymatically from high glucose; contributes to protein glycation.

HbA1c Glycation

Non-enzymatic attachment of glucose to hemoglobin, used to monitor chronic blood sugar levels.

Ground Substance

The gel-like extracellular matrix composed largely of glycosaminoglycans and proteoglycans.

Tetrasaccharide Linker

The common GlcA-Gal-Gal-Xyl sequence that connects GAG chains to proteoglycan core proteins.

GPI Anchor

Glycosylphosphatidylinositol moiety that attaches some proteins (e.g., glypicans) to the membrane.

Sialic Acid

A family of nine-carbon acidic sugars commonly terminating vertebrate glycan chains.

N-Acetylneuraminic Acid

The most common sialic acid, Neu5Ac, often recognized by viral lectins.

L-Fucose

A 6-deoxy-L-galactose commonly found in blood-group antigens.

N-Acetylglucosamine

An amino sugar found in chitin, peptidoglycan, and N-linked glycans.

N-Acetylmuramic Acid

Mur2Ac; a MurNAc derivative forming bacterial peptidoglycan backbones.

Muramic Acid

An ether-linked lactic acid derivative of GlcNAc present in peptidoglycan.