University:
Liberty University
Course:
BIOM 500 | Introduction to Biomedical Sciences
Academic year:

2024
Views:

197

Pages:

6
Author:

Sheha A.

Gluconeogenesis It is the process of formation of glucose from various non-carbohydrate sources. The glucose acts as the second source of energy after glycogen in the body. It occurs mainly in the liver and, to a lesser extent, in the kidneys. This will occur in conditions of supply of glucose (may be due to starvation, fasting or decrease of glycogen level in the body). It involves a series of ten enzymatic steps. Key enzymes of gluconeogenesis: pyruvate carboxylase, phosphoenol pyruvate carboxykinase, fructose 1,6-bisphosphatase, glucose 6-phosphatase. Regulation of Glycogenolysis: Glycogen Phosphorylase is the key enzyme in glycogenolysis. It is activated by phosphorylation by protein kinase A. Epinephrine and glucagon increase the activity of adenylate cyclase which increases the level of cAMP. cAMP activates cAMP-dependent protein kinase A. Calcium also promotes glycogenolysis. Regulation of Glycogenesis: Glycogen synthase is the key enzyme in glycogenesis. It is inactivated by phosphorylation by protein kinase A. Insulin promotes glycogenesis by inactivating protein kinase A and activating protein phosphatase-1. Insulin also promotes glycogenesis by increasing glucose uptake in the cell. Carbohydrates Carbohydrates are organic compounds containing carbon, hydrogen and oxygen. They are classified into monosaccharides, disaccharides and polysaccharides. Monosaccharides: Glucose: It is the most important carbohydrate in the body. It is the primary source of energy for cells. Fructose: It is found in fruits and honey. It is sweeter than glucose. Galactose: It is found in milk. It is a component of lactose. Disaccharides: Maltose: It is formed by the condensation of two glucose molecules. It is found in germinating grains. Sucrose: It is formed by the condensation of glucose and fructose. It is common table sugar. Lactose: It is formed by the condensation of glucose and galactose. It is found in milk. Polysaccharides: Starch: It is a storage form of glucose in plants. It is found in potatoes, rice, and wheat. Glycogen: It is a storage form of glucose in animals. It is found in the liver and muscles. Cellulose: It is a structural polysaccharide found in plant cell walls. It is not digestible by humans. Significance: Maintenance of blood glucose level: Carbohydrates are the primary source of glucose in the body. Glucose is essential for brain function and energy production. Metabolism: Carbohydrates are metabolized to produce energy in the form of ATP. The metabolites of carbohydrate metabolism are used to synthesize other biomolecules. Other functions: Carbohydrates are also involved in cell recognition, cell adhesion, and immune function.