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Lecture notes, cheat sheets
Концепции современного естествознания. Механизм наследственности. Квантовая механика (конспект лекций)
Directory / Lecture notes, cheat sheets Table of contents (expand) LECTURE No. 6. The mechanism of heredity. Quantum mechanics 1. The mechanism of heredity All information about the "plan of the organism" is contained in just one cell, or rather, in the part of the cell, which is called cell nucleus. This core consists of a set of particles. These particles are shaped like a stick or thread, and they are called chromosomes. The number of chromosomes is different: 8, 12, and a person has 48. It would be more correct to say that a cell contains 24 pairs of chromosomes. And it is they who carry the entire encryption code of the body. If you look closely, we will see the similarity of chromosomes. This is due to the fact that part of the chromosomes comes from the mother, i.e. from the egg, and the second part comes from the father, i.e. from the fertilizing sperm. Scientists conducted a study during which it was reliably established that the main "heredity code" is contained in the DNA strand. A strand of DNA makes up chromosomes, in appearance it resembles a grid. This "code of heredity" has its own units. Such a unit for a microorganism is three nucleotides. They are built quite simply - along the length of the DNA molecule. The chromosomes of higher organisms are built much more complicated, but there is an assumption that the process of reading information (although this has not been reliably established) is in general similar to that observed in microorganisms. The body grows by mitosis. Mitosis is sequential cell division. The egg is divided into two "daughter" cells, which are then divided into 4, 8, 16, 32, 64, etc. It should be noted that the frequency of cell division throughout the body is not the same, as a result of which the number of cell divisions is disturbed. In mitosis, the chromosomes double. The meaning of mitosis is that the daughter cells receive exact copies of the set of chromosomes of the egg. From this follows the conclusion that all the cells of the body are similar to each other. Meiosis. After the individual has begun to develop, some of the cells are reserved. The reserved part of the cells is no longer involved in any processes. It is activated only when the individual reaches maturity, and participates in the reproduction of the individual. From this reserved part of the cells, very soon, but before the individual begins to multiply, cells - gametes begin to form. Male gametes are called sperm and female gametes are called eggs. Meanwhile, cells can differ in the number of chromosome sets: 1) cells that have only one chromosome set are called haploid (these are the same gametes); 2) ordinary cells are called diploid; 3) in life there are individuals with three, four or more chromosome sets: triploids, tetraploids, polyploids. 2. Quantum mechanics Quantum mechanics is otherwise called wave mechanics. So, quantum mechanics - this is a theory that establishes the method of describing and the laws of motion of microparticles (elementary particles, atoms, molecules, atomic nuclei) and their systems, as well as the relationship of quantities characterizing particles and their systems with physical quantities directly measured experimentally. Quantum mechanics has helped mankind to describe and understand such phenomena as: 1) ferromagnetism of solids; 2) superfluidity of solids; 3) superconductivity of solids; 4) the nature and origin of neutron stars, white dwarfs and other astrophysical objects was explained. The significance of quantum mechanics does not end there. In theory, quantum mechanics is divided into two types: 1) non-relativistic quantum mechanics; 2) relativistic quantum mechanics. The difference between relativistic and non-relativistic quantum mechanics. Naturally, if there are two directions of quantum mechanics, then they must contradict each other. Through this contradiction one can see the meaning of both non-relativistic and relativistic quantum mechanics. Here are the characteristics that distinguish both directions: 1) non-relativistic quantum mechanics is more "rigorous", it is a complete fundamental physical theory, the main feature of which is its consistency. Relativistic quantum mechanics is more "soft", it admits the presence of contradictions in the theory; 2) in the non-relativistic theory it is considered that the information that helps the interaction is transmitted instantly. Relativistic quantum mechanics, on the other hand, states that the interaction propagates at a strictly defined speed (the so-called "final speed"). Therefore, there must be something that will facilitate such a transfer. And this "helper" is the physical field. One of the founders of quantum mechanics can be called Planck. He was the first to speak out against the theory of thermal radiation that existed at that time. The theory of thermal radiation was based on statistical physics and classical electrodynamics. These two branches of science did not complement each other, but, on the contrary, led to a contradiction in the entire theory of thermal radiation. What is Planck's point of view? And the essence of his point of view is that light is not emitted continuously (as previously thought), but in portions. To be more precise - discrete portions of energy, i.e. quanta. In quantum mechanics, the so-called discrete states are distinguished. The meaning of this state is that a large-scale body continuously changes its speed. Moreover, the change in this speed can occur both in the direction of its increase, and in the direction of its decrease. A variety of physical phenomena are of great importance for changing the speed. It is these phenomena that contribute to an increase in speed or, conversely, to its decrease. An example of a physical phenomenon that contributes to a decrease in the speed of a body is air resistance. To understand this, it suffices to recall the pendulum of a clock: first the pendulum oscillates quite "frequently" and then stops altogether. It is clear that not only Planck played an outstanding role in the development of quantum mechanics. The stages of development of quantum mechanics (this development can be traced in chronological order) look like this: 1) in 1905, Albert Einstein built the theory of the photoelectric effect. This theory was built to develop the ideas of Planck. Einstein suggested that light is not only emitted and absorbed, but also propagated in quanta. Therefore, discreteness is inherent in light itself; 2) in 1913 Bohr applied the idea of quanta to the planetary system of atoms. Bohr's idea led to a scientific paradox. According to Bohr, the radius of the electron's orbit was constantly decreasing. The electron in the end should have simply "fallen" onto the nucleus. Bohr decided that the electron does not emit light all the time, but only when it moves to another orbit; 3) in 1922, the American Compton proved that the scattering of light occurs by the collision of two particles; 4) the Compton effect also led to a paradox. He argued about the corpuscular-wave nature of light. And it was a clear contradiction: these two phenomena could not mix. In 1924, the French scientist Louis de Broglie put forward a theory according to which each particle must be given a wave that is associated with the momentum of the particle; 5) Austrian Schrödinger proved de Broglie's conjecture. Schrödinger came up with an equation that matches the behavior of de Broglie waves. This equation is called the "Schrödinger equation"; 6) in 1926, physicists conducted experiments that experimentally finally confirmed de Broglie's theory; 7) in 1927 Dirac comes up with his own equation, which becomes the main argument of relativistic quantum mechanics. This equation describes the motion of an electron in an external force field. Finally, quantum mechanics as a consistent theory was formed thanks to the works of the German scientist - physicist W. Heisenberg, who created a formal scheme. A feature of this scheme was that instead of mathematical coordinates and mathematical velocities, abstract quantities, the so-called matrices, appeared. Heisenberg's work was developed by other scientists (for example, Born, Jordan, and others). The work of the German physicist Heisenberg became the basis for matrix mechanics. Heisenberg is also the author of the hypothesis that any physical system can never be in a state in which the coordinates of its center of inertia and momentum take on equal values at the same time. This principle is known in science as the "uncertainty relation". According to this principle, the concepts of coordinates and momentum are not applicable to microscopic objects. This is because the experiment never leads to any exact data. This is due not to the fact that the measuring technique is imperfect, but to the objective properties of the microworld. Author: Filin S.P. << Back: Theory of Charles Darwin. Human Origins. Abuse of Darwinism. The evolution of nature >> Forward: Biochemistry (The concept of biochemistry, the history of its appearance. Belozersky Andrey Nikolaevich and his scientific works)
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