An animal carbohydrate reserve. Is the carbohydrate in the animal cell glycogen or starch? What is the reserve carbohydrate of animal cells called?

All the biochemical activity of the animal cell can be described by two verbs: "store" and "expend". The younger the organism, the more processes of synthesis and storage of organic substances will prevail over their splitting and expenditure. The explanation is simple: to grow and "build" your body, you need a lot of plastic material and, of course, energy. The main building material of the cell is protein, and the dominant compound that gives energy is glycogen.

It is considered a reserve carbohydrate, reserved in the cells of the liver and skeletal muscles of all mammals: both animals and humans. The study of its properties will be devoted to this work.

What and where we store

At the level of an animal cell, organic substances are synthesized and accumulated in its structural units - organelles. Proteins are synthesized in ribosomes, lipids and carbohydrates - in the channels of a smooth endoplasmic reticulum. In the body of mammals, stocks of organic substances accumulate in skeletal muscle, liver, subcutaneous fatty tissue and omentum. An animal carbohydrate is glycogen, which is synthesized from glucose contained in the blood.

It is formed as a product of dissimilation of food products, which include, first of all, vegetable starch: bread, potatoes, rice. These substances are split in the oral cavity, stomach, and also in the duodenum. It is in it that their basic decay occurs. The resulting glucose is absorbed into the blood capillaries of the villi of the small intestine and then carried by blood to the muscles and liver, where the reserve carbohydrate of animals and humans is synthesized.

What is glycogen

Although there is a part of the word "glycos" in the name of the substance, which means "sweet" in Greek, it has almost no taste. Most likely, this name indicates its belonging to a class of complex carbohydrates containing glucose residues, really sweet to the taste. Glycogen has the appearance of an unstructured white powder. It is hydrophilic and forms a colloidal solution similar to milk. Being a spare carbohydrate in an animal cell, the polysaccharide undergoes hydrolysis in an acidic environment in several stages. The products of its interaction with water are dextrins, further - maltose and, finally, glucose. Being a polymer, glycogen has the appearance of a mixture of branched chain molecules of different mass.

Biochemical properties

We have established the fact that glycogen is a reserve carbohydrate of the animal cell. Reserve substances of this type undergo in the cytoplasm of hepatocytes, leukocytes and myocytes two mutually opposite processes. The first: dissimilation, which leads to the release of glucose molecules and the second - assimilation, which transfers excess glucose to the reserve polymer - glycogen. It accumulates in the body and is a reserve of energy used in the process of vital activity of animals and humans.

How animal starch is synthesized

Recall that, from the chemical point of view, it is a high-molecular compound - a polymer whose monomers are the residues of α-d glucose. In order for them to be linked together by glycosidic bonds, activation, that is, "swaying" of the sigma bonds of the hexose carbon skeleton, is necessary. This is achieved in the so-called hexokinase reaction. An animal carbohydrate is synthesized from glucose-6-phosphate. This substance is a product of the hexokinase reaction. The enzyme that catalyzes the above mechanism is contained in the cytoplasm of kidney cells, the mucosa of the small intestine and the liver of animals and humans.

The cleavage of glycogen

As we have already explained, the reserve carbohydrate in the animal cage is starch-glycogen. Biochemical studies have established that its cleavage can not occur without the participation of a specific enzyme - phosphorylase. It works in an acidic medium in the presence of molecules of inorganic phosphate. The enzyme itself becomes active under the influence of the hormone of the pancreas - glucagon. His presence in the blood indicates that the level of glucose in it is low. Therefore, the animal body mobilizes the resources of the reserve carbohydrate-glycogen and begins to digest it, in order to obtain an additional portion of glucose.

This process is called glycogenolysis. Neurophysiologists have found that stress hormones - epinephrine and norepinephrine, produced by the adrenal glands - also provoke glycogenolysis.

The liver and its role in the metabolism of carbohydrates

In biology, this largest digestive gland of mammals is called a biochemical plant. Really, in it there is a lot of enzymatic reactions providing a metabolism and energy, that is a metabolism. As already known, the reserve carbohydrate in the animal cell is glycogen. Its disintegration quickly leads to the saturation of blood with glucose, the main source of energy for all mammals and humans.

Lost animal starch is replenished in their organisms by taking starchy food: potatoes, bread, rice. All these products are digested in the digestive tract, and the resulting glucose enters the bloodstream, and from it into the cells, especially the skeletal muscles and liver. They synthesize animal starch under the action of the enzyme glucopyrophosphorylase.

What processes occur in skeletal muscles

As in the liver, in myocytes - muscle cells, animal starch accumulates. Since the mass of muscles is much larger than the weight of the liver, the glycogen content in them is much higher. During exercise, animal starch begins to split. Lactic acid, formed as a result of glycolysis, enters the bloodstream and is transported to the liver and kidney cells. In them, from each two molecules of lactic acid, one mole of glucose is synthesized, which is then converted to a reserve polysaccharide. The reaction occurs with the use of ATP energy. Thus, the reserve carbohydrate of the animal cell is glycogen, accumulated by myocytes, hepatocytes, cells of the cortical layer of the kidneys, myocardium and lung cells.

The role of enzymes in the metabolism of animal starch

As it was established earlier, the reserve carbohydrate of animal cells is called glycogen. As a result of two mutually opposite directions in metabolism: cleavage and synthesis, it also participates in these reactions. The mutual transformation of glucose into glycogen and vice versa is possible only with the participation of a complex enzymatic system in these reactions. It includes catalysts for glycogenogenesis, such as: phosphoglucomutase (converting glucose-6-phosphate to glucose-1-phosphate) and UDP-glucopyrophosphorylase (ensures the irreversibility of glycogen synthesis). The cleavage reactions occur in the presence of glycogen phosphorylase and two other enzymes that successively cleave the side branches in the glycogen chains. The system of all the above enzymes acts only on the exchange of glycogen in the heterotrophic animal cell, so the correct answer to the test question: the reserve carbohydrate in the animal cell is: 1. Brain, 2 Glycogen? - there will be a statement under number 2.

Disorders of carbohydrate metabolism and its consequences

Based on the above facts, we found that the reserve carbohydrate in the animal cell is glycogen. Violations of its exchange can be caused by two types of causes. The first - errors in nutrition and lifestyle, the second - congenital malformations in the work of the enzymatic system of the body. The set of enzymes related to it, is responsible both for the cleavage of the animal starch, and for its formation from glucose in the blood. Therefore, pathologies occur both in the reactions of plastic metabolism, and energy. They are called glycogenoses. As defined above, the reserve carbohydrate in the animal cell is glycogen, accumulating primarily in the liver and skeletal muscles. Hence, there are two types of syndromes: muscle and liver etiology. The first group includes Mc-Ardl's disease. The patient does not produce an enzyme phosphorylase. This leads to the appearance in the urine of the chromoprotein - myoglobin, released during heavy physical work. As a consequence, there is a destruction of muscle tissue and the appearance of convulsive conditions.

To hepatic syndromes is Girke's disease. It occurs most often, beginning with the infant age. In patients in liver cells, there is no enzyme that transfers the product of primary glycogen cleavage into glucose, so a very low level of sugar (hypoglycemia) is observed in the blood of the patient, and acetone appears in the urine, which causes intoxication of the organism.

In this article we considered the mechanisms of the exchange of animal starch - glycogen, which takes place in mammalian and human cells.