CARBOHYDRATE METABOLISM

3.1 INTRODUCTION
All living cells require energy to carry out various cellular activities. This energy
is stored in the chemical bonds of organic molecules (e.g. carbohydrates, fats,
proteins) that we eat as food. These organic molecules are broken down by
enzymatic reactions in cells to generate energy in the form of adenosine
triphosphate (ATP). The ATP generated by these pathways in cells is used to
drive fundamental cellular processes. The food we consume is mainly comprised
of proteins, polysaccharides (carbohydrates) and fats. These are first broken
down into smaller units: proteins into amino acids, polysaccharides into sugars,
and fats into fatty acids and glycerol. This process of digestion occurs outside
the cell. The amino acids, simple sugars and fatty acids then enter the cell and
undergo oxidation by glycolysis (in the cytosol) and the citric acid cycle (in the
mitochondria) to generate ATP (from ADP and Pi).
OBJECTIVES
After reading this lesson you will be able to
z describe glycolysis, Citric Acid Cycle
z explain Glycogenesis and Glycogenolysis
z describe the Hormonal regulation of blood sugar level
3.2 GLYCOLYSIS (EMBDEN-MEYERHOF PATHWAY)
Definition
In glycolysis pathway glucose is converted to pyruvate (aerobic condition) or
lactate (anaerobic condition), along with production of a small quantity of energy.