Work Sheet 19
Overview of
Carbohydrate Metabolism
1. Define the following terms: monosaccharide, polysaccharide, asymmetric
carbon, glycosidic bond and reducing sugar.
Monosaccharide: aldehyde of ketone derivatives of polyhydroxy
alcohols
Polysaccharide: polymers of monosaccharides held together by glycosidic bonds
Asymmetric Carbon: chiral carbon
Glycosidic Bond: bond holding two or more monoscccharides together
Reducing Sugar: the state of the oxygen on the anomeric carbon determines whether a
sugar can react with oxidized compounds such as copper or iron. If the oxygen
on the anomeric carbon is not attached to some other structure, such as a metal
or another sugar, then it is a reducing sugar. Oxygen can donate electrons to
reduce copper or iron
2. Identify the composition of the following
disaccharides: a-lactose, b-sucrose and b-maltose.
Lactose: Galactose and Glucose
Sucrose: Glucose and Fructose
Maltose: Glucose and Glucose
3. Discuss the
difference between insulin-sensitive
and insulin-insensitive glucose transport.
Insulin-Insensitive: uptake of glucose by the liver, brain and RBC is
maximally active in the absence of insulin, insulin-insensitive. Since glucose
reaches the liver before it signals the pancreas to release insulin it is
important that the liver function independently of insulin. -----> prevents
hyperglycemia.
Insulin-Sensitive: associated with glucose promoting pancreatic
release of insulin.
4. Define
the pathways of the carbohydrate system.
Glycolysis: splits glucose to pyruvate, which can be converted to lactate.
Gluconeogenesis: converts pyruvate to glucose.
Glycogenesis: synthesis of glycogen, carbohydrate fuel storage form.
Glycogenolysis: breakdown of glycogen.
Pentose Phosphate Pathway (PPP): produces NADPH for cell biosynthesis.
Citric Acid Cycle: converts Acetyl CoA to CO2 and ENERGY