Glükogenees

Glükogenees, also known as glycogen, is a multibranched polysaccharide that serves as a major energy reserve in the body. It is primarily stored in the liver and muscles, where it can be rapidly broken down to glucose when energy is needed. Glycogen synthesis and breakdown are tightly regulated processes that occur in response to hormonal signals, such as insulin and glucagon.

Glycogen is synthesized from glucose through a series of enzymatic reactions catalyzed by glycogen synthase. This process occurs primarily in the liver and muscle cells, where glucose is converted into glucose-1-phosphate and then into UDP-glucose. UDP-glucose is then used to add glucose units to a growing glycogen chain, which is initiated by glycogenin.

Glycogen breakdown, or glycogenolysis, is the process by which glycogen is converted back into glucose. This process is initiated by the hormone glucagon, which activates glycogen phosphorylase, an enzyme that catalyzes the breakdown of glycogen into glucose-1-phosphate. Glucose-1-phosphate is then converted into glucose-6-phosphate, which can be used to regenerate ATP or be converted into other glucose derivatives.

Glycogen plays a crucial role in maintaining blood glucose levels and providing energy during periods of fasting or physical activity. Its synthesis and breakdown are tightly regulated to ensure that the body has a sufficient supply of glucose when needed, while also preventing excessive glucose levels that could lead to hyperglycemia.