Carbohydrates Flashcards
What are monomers?
many identical or similar building blocks (monomers) linked covalently together
What is a homopolymer?
identical monomers
What is a heteropolymer?
different monomers branched or unbranched (linear)
biological polymers.
What are condensation reactions for?
Formation of biomacromolecules
What is hydrolysis for?
Degradation (digestion) of biomacromolecules
What are the roles of carbohydrates
metabolism-sources of energy and carbon skeleton
structural- used by plants, microorganisms and some animals
cell recognition
protection- anti-freeze and anti-desiccation
Formation of disaccharides?
Condensation reaction used to form a glycosidic link
Uses of polymers with examples?
glycogen in animals used for storage
structural found in plant cell walls (cellulose)
arthropod exoskeletons (chitin)
What does each branched polysaccharide have at the ends?
Each branch has 1 non-reducing end
Entire polymer has 1 reducing end
What is Glycogen?
It is a storage polysaccharide that is branched
with a homopolymer of glucose.
(1→4) links
(1→6) links
glycogen granules have >100,000 glucose residues
What is Glycogen: helical structure
Alpha-linkage and flexible chains
left-handed (anticlockwise) helix
with hydrogen bonding between adjacent residues stabilising the helix.
Structural polysaccharides Chitin
Arthropod exoskeleton, insects, crustacea.
Found in fungal cell walls
(1->4) links.
Chitin is a linear homopolymer of N-acetylglucosamine.
It is a structural polysaccharide with a laminar structure stabilised by hydrogen bonds and hydrophobic interactions.
What is the Chitin: laminar structure
Beta-linkage= rigid rod-like molecules
strong hydrogen bonding between adjacent sugar residues
acetamido group
Chitin: structural interactions
parallel array
hydrogen bonds between adjacent molecules with a non-reducing end and a reducing end
The chitin stack and row interactions- extensive non-covalent bonding and its insoluble
What are polyols?
They contain either an aldehyde or a ketone group and are sugar alcohols.
What are reducing sugars?
Disaccharides in which one sugar residue can interconvert between linear and cyclic forms.
What are diastereoisomers
stereoisomers not related as mirror images.
What has supra-molecular complexes?
lipids (not all bound together just associated together) and these are involved in membranes
aldose sugars
ketose sugars
They all have an aldehyde group
They all have a ketone group
Glucose, fructose and their hemiacetal and hemiketal formations.
In aqueous solution glucose, fructose, and other sugars of five or six carbons rapidly interconvert between straight-chain and cyclic forms, the cyclic forms are intramolecular hemiacetals and hemiketals.
The cyclic form of glucose is a six-membered ring, with an intramolecular hemiacetal formed by attack of the hydroxl on the fifth carbon on the aldehyde carbon . This carbon is called the anomeric carbon. The cyclic form of glucose is called glucopyranose.
Fructose in solution forms a six-membered cyclic hemiketal called fructopyranose when the hydroxyl on C6 attacks the C2 ketone carbon.
In the formation of fructofuranose from open-chain fructose, the hydroxyl group on the fifth carbon attacks the ketone.
