Hexose vs Pentos
Carbohydrates yog ib pawg ntawm cov tebchaw uas txhais tau tias "polyhydroxy aldehydes thiab ketones lossis cov khoom uas hydrolyze kom tawm los polyhydroxy aldehydes thiab ketones." Carbohydrates yog hom ntau tshaj plaws ntawm cov organic molecules hauv ntiaj teb. Lawv yog lub hauv paus ntawm chemical zog rau cov kab mob nyob. Tsis tas li ntawd xwb, lawv ua haujlwm tseem ceeb ntawm cov ntaub so ntswg. Carbohydrate tuaj yeem muab faib ua peb yam xws li monosaccharides, disaccharides thiab polysaccharides. Monosaccharides yog hom carbohydrate yooj yim tshaj plaws. Monosaccharide muaj cov qauv ntawm Cx(H2O)x Cov no tsis tuaj yeem hydrolyzed rau hauv cov carbohydrates yooj yim. Lawv qab zib hauv saj. Tag nrho cov monosaccharides txo cov suab thaj. Yog li, lawv muab cov txiaj ntsig zoo nrog cov txiaj ntsig 'lossis Fehling's reagents. Monosaccharides raug cais raws li,
- Tus naj npawb ntawm cov pa roj carbon atoms nyob hauv cov molecule
- Txawm tias lawv muaj aldehyde lossis keto pawg
Yog li ntawd, yog cov monosaccharide muaj ib pawg aldehyde, nws hu ua aldose. Ib qho monosaccharide nrog pawg keto hu ua ketose. Ntawm cov no, cov monosaccharides yooj yim tshaj plaws yog glyceraldehyde (ib qho aldotriose) thiab dihydroxyacetone (ib ketotriose). Glucose yog lwm qhov piv txwv rau monosaccharide. Rau monosaccharides, peb tuaj yeem kos ib kab lossis ib lub voj voog. Hauv kev daws, feem ntau ntawm cov molecules yog nyob rau hauv cov qauv cyclic. Piv txwv li, thaum lub cyclic qauv tsim nyob rau hauv qabzib, lub -OH ntawm carbon 5 yog hloov dua siab tshiab rau hauv ether linkage, kaw lub nplhaib nrog carbon 1. Qhov no tsim ib tug rau lub nplhaib qauv. Lub nplhaib hu ua hemiacetal nplhaib, vim muaj cov pa roj carbon uas muaj ob qho tib si ether oxygen thiab ib pawg cawv
Hexose
Raws li tau piav qhia saum toj no, ib txoj hauv kev ntawm kev faib cov monosaccharides yog siv cov pa roj carbon atoms tam sim no hauv cov molecule. Yog li, hexose yog pawg ntawm monosaccharides nrog rau 6 carbon atoms. Nws muaj cov tshuaj formula C6H12O6 Piv txwv li, qabzib, galactose, fructose yog ib co ntawm cov molecules uas muaj rau carbon atoms. Piv txwv li, cov piam thaj muaj plaub pawg hydroxyl thiab muaj cov qauv hauv qab no.
Cov no tau muab faib ntxiv raws li seb lawv puas muaj pawg aldehyde lossis pawg ketone. Piv txwv li, qabzib muaj ib pawg aldehyde; Yog li ntawd, nws yog aldohexose. Allose, altrose, qabzib, mannose, gulose, idose, thiab talose yog lwm hom aldohexoses. Tag nrho cov no muaj plaub chiral chaw, yog li muaj 16 stereoisomers. Thaum lawv tsim cyclic molecules, lawv tsim hemiacetals. Fructose muaj ketone pawg, yog li nws yog ketohexose. Lwm yam tshaj li fructose, sorbose, tagtose, thiab psicose yog qee yam ketohexoses. Lawv muaj peb lub chaw chiral thiab yog li ntawd, yim stereoisomers.
Pentose
Pentoses yog monosaccharide molecules nrog tsib carbon atoms. Raws li hexoses, pentoses tseem tuaj yeem muab faib ua ob pawg li aldopentoses thiab ketopentoses. Ribose, xylose, arabinose, lyxose, yog aldopentoses. Lawv muaj peb lub chaw chiral, yog li yim stereoisomers. Ribulose, xylulose yog ketopentoses, thiab lawv tsuas muaj ob lub chaw chiral.
Qhov txawv ntawm Hexose thiab Pentose yog dab tsi?
• Hexose yog pawg ntawm monosaccharides nrog rau 6 carbon atoms whereas pentose yog pawg ntawm monosaccharides nrog tsib carbon atoms.
•Hexose molecules muaj ntau qhov chaw chiral dua li pentose molecules. Yog li, tus naj npawb ntawm cov stereoisomers tau los ntawm hexose molecules yog siab dua li ntawm pentoses.
