Carbohydrate and sugar structure
Carbohydrates or saccharides are essential
components of living organisms.
(C•H2O)n Where n=3 or greater.
A single saccharide is called a monosaccharide.
Oligosaccharide is a few linked monosaccharides
and are at time associated with proteins
(glycoproteins) or lipids (glycolipids)
Polysaccharides consist of many monosaccharides
i.e. cellulose or glycogen
The Fischer convention, the basis for the D-
configuration in sugars comes from D-glyceraldhyde’s
configuration around its asymmetric carbon.
Epimers differ in configuration around one carbon atom i.e. D-
glucose and D-mannose but D-glactose and D-glucose are not
epimers because they very around two carbon atoms. There are 2n-2
Carbohydrates are classified as to the nature of the
carbonyl group : ketone = ketose aldehyde = aldose
Monosaccharides can form ring structures
Glycosidic binds are between two sugars
They can either be in the α or β configuration and
can be linked through the 1-2, 1-4 or 1-6 linkage
Sugar Polymers The Polysacchrides
• Energy Storage
– Starch α-amylose and amypectin
– Cellulose and Chitin
Metabolism is the overall process through
which living systems acquire and utilize free
energy to carry out their functions
The coupling of exergonic reactions of nutrient
breakdown to the endergonic processes is
required to maintain the living state
How do living things acquire the energy needed for
Phototrophs- acquire free energy from sunlight
Chemotrophs - oxidize organic compounds to
ATP is the energy carrier for most
A series of consecutive biochemical reactions catalyzed
by enzymes that produce a specific end product.
Catabolism- the breakdown of food stuffs to simple
Anabolism- the synthesis of biomolecules from simple
The breakdown of foods converge to a few simple
Very Few metabolites are used to synthesize a large
variety of biomolecules
•Acetyl-Coenzyme A (acetyl-CoA)
•Citrate acid cycle intermediates
Three main pathways for energy production
•Citric acid cycle
Certain pathways are
involved in both
breakdown and buildup
of molecules these
pathways are called
amphibolic. The citric
acid cycle is an example
Metabolic pathways are irreversible
They have large negative free energy changes to
prevent them running at equilibrium.
If two pathways are interconvertible (from 1 to 2
or 2 to 1), the two pathways must be different!
Independent routes means
independent control of
The need to control the
amounts of either 1 or 2
independent of each other.