Biopsychology and fatalism

Genetic variation? The phenomenon that biological parents can produce offspring similar to themselves is called heredity. The basis of genetic material is deoxyribonucleic acid (DNA). Parents pass on their genetic material DNA to their offspring, and their genetic traits and species remain relatively stable. The reason why life can continue from generation to generation is mainly due to the inheritance of genetic material from generation to generation in the biological process, which makes the offspring have similar characteristics to the previous generation.

However, between parents and offspring, and between individuals of offspring, it is absolutely not exactly the same, that is to say, there are always more or less differences, which is called variation. ?

Heredity and variation are common phenomena in biology, and they are also the basis of species formation and biological evolution. ?

Microbial genetics, as an independent discipline, was born in 1940s. Viral genetics is the focus of microbial genetics.

The main components have played an important role in promoting the study of biological heredity and variation, and are also very important for molecular genetics?

Development laid the foundation. Many biological characteristics of the virus, including simple structure, asexual proliferation, can cross cells?

Rapid culture, proliferation and easy purification make it a unique material for genetic research. ?

As we all know, the material basis of all kinds of biological inheritance, including viruses, is nucleic acid. In fact, this conclusion?

The first direct evidence comes from the study of viruses. To illustrate this point, let's review two classics first?

Classic experiment: ① Phage infection test: T2 is a phage infected by Escherichia coli, which consists of protein shell (?

About 60%) and DNA core (about 40%). Protein contains sulfur and DNA contains phosphorus. Release? 3? 2P and? 3? 5S？

Mark T2?

The function of DNA and protein can be determined by infection test with labeled phage. Hershey and?

Datong (1952) includes? 3? 2P or what? 3? T2 was infected with Escherichia coli in 5S medium to obtain labeled phage.

However?

After that, the conventionally cultured Escherichia coli was infected with the labeled phage, and then the isotopic label of the host cell was determined.

3? When 5S-labeled phage is infected, there are few isotope labels in the host cells, most of which are? 3? 5S-labeled phage?

Body egg?

White is attached to the outside of the host cell. 3? When the 2P-labeled phage is infected, most radioactive labels are in the host.

Intracellular. Obviously, it is mainly DNA that enters cells during infection. ② Virus reconstruction experiment: Tobacco mosaic virus?

(tobacco? Mosaic? The virus (TMV) consists of protein shell and RNA core. Can be extracted from TMV alone?

Its protein part and RNA part. Frank Cole? Courat( 1956) experiment proves that these two components are used for division?

Don't inoculate tobacco, only viral RNA can cause infection. Although the infection efficiency is low, it is enough to show that the genetic material is?

Ribonucleic acid. Franco? Courat first obtained the protein shell and psyllium of TMV by separation and then polymerization.

Poison (Sherlock Holmes? Ribs? Grass? Virus, HRV) RNA, and then combine them to form a hybrid virus, this?

Hybrid virus has the shell of common TMV and can be inactivated by anti-TMV antibody, but it is not affected by anti-HRV antibody. What time?

When tobacco is infected with hybrid virus, it will produce special lesions infected with HRV. The virus isolated from it can be treated with anti-HRV antibody.

Deactivate. On the contrary, protein of HRV combined with RNA of tobacco mosaic virus obtained similar results. Have you been able to?

Many small RNA viruses and some DNA viruses extract infectious nucleic acids. As described in Chapter 4, these infectious nucleic acids exist in?

After infecting cells, complete progeny virus with protein capsid and lipid envelope can be produced. Through polio?

The hybrid virus composed of viral RNA and Coxsackie virus capsid will produce offspring virus after infecting cells.

All polio viruses. The above facts show that nucleic acid is the decisive mechanism of virus inheritance, while protein capsid and?

Liposomes are only components synthesized under the control of the genetic information of viral nucleic acids or "robbed" by cells. These ingredients?

Although it determines the antigenic characteristics of the virus, it is also related to the adsorption of the virus to cells, which affects the disease to some extent.

The relationship between virus and host cells or organisms, such as infection and immunity, but from the biological nature of virus, it?

Children are just subsidiary or auxiliary structures in virus particles. The basis of transmitting genetic information by nucleic acid lies in its base arrangement?

Sequence, viral nucleic acid replication can produce new nucleic acid molecules exactly the same as the original nucleic acid, thus maintaining genetic stability?

Qualitative. However, the virus has no cell structure and lacks an independent enzyme system, so its genetic mechanism is influenced by the surrounding environment.

The influence, especially the internal environment of host cells, is particularly profound; In addition, the virus proliferates quickly, and the probability of mutation is also corresponding?

Increase, which in turn determines the greater uncertainty of virus inheritance-variation. Appropriate breeding methods are often used.

Many mutant strains were obtained quickly. Using various physical, chemical and biological factors for mutation, we can also see the results quickly. ?

Hybridization or recombination between virus particles and virus nucleic acid opens up the study of virus genetic variation.

The prospect is broad. These convenient conditions make the study of virus genetic variation far beyond the scope of virology itself, and become?

An important model and profile for human beings to understand the nature and laws of life. ?

Heredity and variation are the unity of opposites. Heredity allows species to continue, and variation allows species to evolve. Ben.

This chapter mainly discusses the phenomenon and mechanism of virus mutation, and the methods of studying mutation and mutation factors.

Please refer to related professional books for genetic theory. ?

The genetic variation of virus is often a "group", that is, the same expression of countless virus particles. What about the virus component?

In particular, viruses encode enzymes and protein, which are usually mixed with normal enzymes in cells and protein. Is this obvious?

This increases the complexity of identifying the genetic variation characteristics of viruses. ?

Variation is a universal feature of living things. Even before humans discovered the virus, they began to use mutations?

Make vaccines. For example, 1884, Pasteur isolated the street virus (virulent virus) of rabies by continuous passage of rabbit brain.

Become a fixed poison. This fixed virus retains its original immunogenicity, but its virulence has changed-not brain infection?

After inoculation, the toxicity to humans and dogs was obviously reduced, so it was successfully used as a preventive agent for rabies. Since then, in Xu?

In the aspect of multi-animal virus, attenuated strains were obtained by the same or similar methods, and many high-quality vaccines were created. Choice?

Great achievements have also been made in cultivating natural attenuated mutants. But understanding the mechanism of virus genetic variation,

Only in recent decades has significant progress been made. This is not only a leap in virology itself, but also a leap in other disciplines.

In particular, new technologies such as biochemistry, molecular biology, immunology, electron microscopy and isotope labeling have developed rapidly.

The results of the exhibition. ?

Variation mainly refers to gene mutation, gene recombination and chromosome variation. Among them, gene mutation is the fundamental source of new biological genes, which is also the fundamental source of biodiversity. Humans can create and utilize more biological resources through artificial mutation, such as radiation, laser, virus and some chemicals (usually colchicine) can be mutated. ?

Heredity is the only way to breed new species after mutation. Only through heredity can mutation be manifested in the next generation. ?

There are always more or less differences between parents and offspring, and between individuals of offspring, which is the phenomenon of biological variation. Some biological variations are heritable while others are not. Genetic variation refers to the variation that an organism can pass on to its offspring. This variation is caused by the change of genetic material. Non-genetic variation is caused by external factors such as light and water, and will not be passed on to future generations.