Life and energy ... Both concepts are interconnected, all manifestations of the vital activity of organisms on planet Earth are energy dependent. Rotations of the stems and flowers of plants following the movement of the Sun, the beating of a human heart, the flapping of wings of birds - this requires energy. Inside the microscopic cell, too, everything is filled with movement: its liquid contents move clockwise, thousands of molecules enter the cellular organoids, carrying out metabolic reactions.
Energy is needed for vital manifestations, it takes the form of a special substance - adenosine triphosphoric acid (ATP). In our work, we will answer the following questions: what is the structure of the energy substance? What is the function of an ATP molecule in a cell? A description of the role of adenosine triphosphoric acid can also be found in our article.
From what sources does energy enter the body?
From the external environment, biological systems can receive energy in different ways. For example, due to the oxidation of the nutrients that make up the food. As a result of chemical processes related to dissimilation, a certain portion of energy is released. So, the oxidation of 1 g of fat gives 38.9 kJ of energy. In this way animals, mushrooms, humans receive energy, and ATP molecules in the cell perform the function of energy currency. Without food, the source of their activity, such organisms would simply perish. Plants themselves can form food for themselves from carbon dioxide and water, using light radiation as an energy source. The glucose synthesized in their cells is used as a food product for the plant itself. Oxidation of it 1 g gives 17.2 kJ of energy, which explains the role that ATP molecules play - they are the accumulators of cellular energy.
Where adenosine triphosphoric acid is consumed
Newborn baby mammals quickly begin to grow and develop, provided there is enough high-calorie nutrition. Mother's milk provides their body with all the beneficial substances. They are processed in the process of dissimilation, and the released energy is stored in the form of ATP molecules. The growth of an organism is a synthesis of compounds inherent only to it and ensuring cell division. It lies at the heart of growth processes.
ATP molecules perform the function of energy supply in the cell, because the condition for carrying out such reactions is the presence of energy, which will be spent on assimilation reactions. Both types of reactions: the synthesis of plastic compounds, which provides growth processes and the breakdown of nutrients that provide energy for them, are interconnected. This connection is called energy conjugation. It determines what function in the cell performs the ATP molecule.
What should be a universal energy substance?
The mediator, which the cell will use as an energy source, must have a certain specificity of its composition and spatial configuration of the molecule. Such a substance should not have a large mass and size and be sufficiently mobile. The stability and stability of its molecule is another requirement, the fulfillment of which will ensure the ability of the compound to accumulate and preserve. All these criteria are met by particles of adenosine triphosphoric acid, therefore, in the cell, ATP molecules perform the function of energy conservation.
Features of the chemical structure
The nitrogen-containing base - adenine, combined with pentose (ribose and the three residues of orthophosphate acid) - this is the composition of the adenosine triphosphoric acid molecule. In an aqueous medium containing a specific enzyme, it can cleave one or two acid residues, turning into adenosine diphosphoric and adenosine monophosphoric acid. These reactions occur at the time the cell uses the energy necessary, for example, for its division, growth, and anabolic processes.
ATP molecules in the cell perform the function of providing energy to the motor processes and transport of compounds through the membrane. The movement of particles of substances, organelles, fluttering of flagella or cilia and some other phenomena of cellular vital activity are impossible without special motor peptides. These include, for example, myosin. This is a muscle protein with a complex structure. It breaks down adenosine triphosphoric acid, coordinating muscle contractions. This fact shows what function in the cell is played by the ATP molecule.
Transfer of compounds across cell membranes
Cells are not only complexly organized, but also open biological systems. This means that between them and the external environment there is a continuous exchange of ions or molecules of various compounds. The most important condition for the life of the cell is the difference in the concentration of substances between it and the intercellular fluid. ATP molecules in the cell function as a substrate for various transport peptides, for example, such as a sodium-potassium pump.
Active transport
This is the transfer of particles through cell membranes, provided that this process occurs against a concentration gradient. Located in the membrane of an animal cell, the protein removes three sodium ions from the cell and transports two potassium cations into it. For this work, the sodium-potassium pump consumes one molecule of energy substance. In this case, the compounds move from the site with a low concentration in the region of its high concentration.
Thus, the active transport of substances, involving ATP, contributes to the interconnection of cells with the environment. Therefore, the definition in molecular biology of the role that ATP molecules play is as follows: adenosine triphosphoric acid serves as the most important energy mediator used by living organisms to ensure all manifestations of its vital activity.