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: -lactose, -sucrose and
-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