BCH2011 Study Guide - Midterm Guide: Stereocenter, Carbonyl Group, Covalent Bond
25 May 2018
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Carbohydrates and Glycoconjugates
• Hydrophilic
• General formula: (CH2O)n
• Also contains nitrogen, phosphorous and sulphur
• Open chain or cyclic structure
o Majority cyclic (4 or more carbons)
• Functions
o Energy source and storage
▪ Fibre source
▪ Glucose – short term
▪ Glycogen – long term
o Metabolic intermediates: amino acids and nucleic acids
o Information storage/transfer: DNA, RNA
o Structure / protective elements: cell walls and extracellular matrix
o Recognition/signaling
o Adhesion
o Lubrication of joints
Monosaccharides (one sugar unit)
• Reducing agents
• Single ring: glucose, galactose, fructose
o Name ends in ‘-ose’
• Two families are either aldose or ketose
o Single polyhyroxy aldehyde or ketone unit
o Aldehyde
▪ Carbon shares double bond with
oxygen and single bond with
hydrogen
▪ Carbonyl group at end of chain
o Ketone
▪ Carbon shares double bond with oxygen and remaining two
bonds two carbons or hydrocarbons
▪ Carbonal group and any other position
• Asymmetric centres (chiral carbon: 4 different types of groups)
• Most abundant: six carbon sugar D-glucose (dextrose)
• Classified according to:
1. Carbonyl group
2. Number of carbons
Glucose
Fructose
Galactose
Carbonyl group
Aldehyde:
aldohexose/aldose
Ketone:
ketohexose/ketose
Aldehyde: aldose
• Forming cyclic form of glucose
o Carbonyl group forms covalent bond with oxygen of hydroxyl (-OH)
group along the chain
• Ring closure
o Carbonyl group forms covalent bond with oxygen of OH group → new
chiral centre
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Information storage/transfer: dna, rna: metabolic intermediates: amino acids and nucleic acids, structure / protective elements: cell walls and extracellular matrix, recognition/signaling, adhesion, lubrication of joints. Disaccharide (two monosaccharides: sucrose, maltose, lactose, formed by hydroxyl group of one sugar reacting with anomeric carbon of other sugar (condensation reaction) Non-reducing sugar (table sugar): no unsubstituted anomeric carbon. Polysaccharide: more than 10 sugar units, all polymers of glucose, starch, cellulose, glycogen (homopolysaccharide, all polymers of glucose. Two types of glucose polymers: amylose (20%) and amylopectin (80%) Linear, unbranched branched: heteropolysaccharides: contain several types of monosaccharides(structural support), agarose (seaweed, sulfate group: affects structure/solubility, peptidoglycan (bacteria, n-acteyl, glycosaminoglycans (animals) Extracellular matrix: glycosaminoglycans: components of extracellular matrix, large role in, adhesion, proliferation, migration, survival, components (3 classes, collagens and elastins (structural proteins, proteoglycans (protein polysaccharide complexes: structural, fibronectins and laminins (glycoproteins: attach cells to matrix) Glycosaminoglycans: linear polymers, repeating disaccharide, one of the 2 monosaccharides is always either, n-acetyl glucosamine or, n-acetyle galactosamine, form proteoglycans.
