Carbohydrates. Carbohydrates serve a variety of functions Energy storage and food Structure and...
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Transcript of Carbohydrates. Carbohydrates serve a variety of functions Energy storage and food Structure and...
![Page 1: Carbohydrates. Carbohydrates serve a variety of functions Energy storage and food Structure and support Lubrication Protection Recognition and signaling.](https://reader035.fdocuments.us/reader035/viewer/2022062805/5697bfe31a28abf838cb4fd8/html5/thumbnails/1.jpg)
Carbohydrates
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Carbohydrates serve a variety of functions
Energy storage and food
Structure and support
Lubrication
Protection
Recognition and signaling
Component of nucleotides
starch
mucin (glycoprotein)
surface glycoproteins
cell wall peptidoglycan
chitin and cellulose
2-deoxyribose
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Carbohydrates are polyhydroxylated aldehydes (aldoses) and ketones (ketoses)
‘glyc’ (from Greek glykys = sweet) also designates carbohydrateex: glycoside, glycolysis, peptidoglycan
‘-ose’ suffix indicates
carbohydrate
Saccharide: from Greek sakcharon
= sugar
Monosaccharides (sometimes called ‘simple sugars’)
also, Oligosaccharides (disaccharides, trisaccharides, …) and Polysaccharides (sometimes called ‘complex carbohydrates’)
Base formula: CnH2nOn
Formed from monosaccharides linked via a condensation reaction
triose tetrose pentose
# of carbons
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Most carbohydrates are chiral, and their configuration is a major distinguishing featureBase formula: CnH2nOn
Chiral carbons:#C - 2 for aldoses#C - 3 for ketoses
Number of stereoisomers: 2x, where x is # of chiral carbons
D-aldopentoses are diastereomers
D- and L- arabinose are enantiomers
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A carbonyl and an alcohol will readily react to form a new chiral center
This is how monosaccharides spontaneously cyclize
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Figure 8-4
Mutarotation is the interconversion of anomers
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A six-membered sugar ring, like glucopyranose, adopts one of two chair conformations
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Modified sugars are important in biochemistry
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A hemiacetal or hemiketal may condense with an alcohol to form an acetal or ketal
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Figure 8-7
Glycosidic bonds link the anomeric carbon to other compounds, to form ‘glycosides’
O-glycosidic (or O-glycosyl) bonds (or linkages)
Can these sugars interconvert?
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Page 226
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Condensation reactions link monosaccharides into disaccharides (and polysaccharides)
non-reducing end reducing end