Nucleic acids as opposed to proteins. Chemical composition and structure of nucleic acids. Participation in protein biosynthesis. Proteins, as opposed to nucleic acids

1. Viral functions nucleic acids

2. Viral proteins

3. Processes of interaction between a virus and a host cell

1.Function of viral nucleic acidsregardless of their type consists of storage and transmission genetic information. Viral DNA can be linear (as in eukaryotes) or circular (as in prokaryotes), but unlike the DNA of both, it can be represented by a single-stranded molecule. Viral RNAs have different organization(linear, circular, fragmented, single-stranded and double-stranded), they can be represented by plus or minus strands. Plus threads functionally identical to mRNA, i.e., they are capable of translating the genetic information encoded in them to the ribosomes of the host cell.

Minus threads cannot function as mRNA, and the synthesis of a complementary plus strand is necessary for translation of the genetic information contained in them. RNA of plus-strand viruses, in contrast to RNA of minus-strand viruses, have specific formations necessary for recognition by ribosomes. In double-stranded DNA- and RNA-containing viruses, information is usually recorded in only one strand, thereby saving genetic material. 2. Viral proteins by localization V virion divided:

On capsids;

Supercapsid proteins;

Genomic.

Capsid shell proteins in nucleocapsid viruses perform protective function - protect viral nucleic acid from adverse effects - and receptor (anchor) function, ensuring the adsorption of viruses on host cells and penetration into them.

Supercapsid shell proteins, like capsid shell proteins, perform protective And receptor function. These are complex proteins - lipo- and glycoproteins. Some of these proteins can form morphological subunits in the form of spiked processes and have the properties hemagglutinins(cause agglutination of red blood cells) or neuromi nidases(destroy neuraminic acid, which is part of cell walls).

A separate group make up genomic proteins, they covalently linked with the genome and form ribo- or deoxyribonucleoproteins with the viral nucleic acid. The main function of genomic proteins is participation in the replication of nucleic acid and the implementation of the genetic information contained in it, these include RNA-dependent RNA polymerase and reverse transcriptase.

Unlike capsid and supercapsid shell proteins, these are not structural, but functional proteins. All viral proteins also perform the function of antigens, since they are products of the viral genome and, accordingly, foreign to the host organism. Representatives of the kingdom Vira Based on the type of nucleic acid, they are divided into 2 subkingdoms - riboviral and deoxyriboviral. Subkingdoms are divided into families, genera and species. Virus belonging to a particular family (there are 19 in total) is determined:

structure and structure of nucleic acid;

Type of symmetry of the nucleocapsid;

Presence of a supercapsid shell. Belonging to one or another genus or species is associated with others biological properties viruses:

Virion size (from 18 to 300 nm);

Ability to reproduce in tissue cultures and chicken embryos;

The nature of changes occurring in cells under the influence of viruses;

Antigenic properties;

Ways of transmission;

Surrounded by susceptible hosts.

Viruses - pathogens of human diseases refer to 6 DNA- containing families (poxviruses, herpesviruses, hepadnaviruses, adenoviruses, papovaviruses, parvoviruses) and 13 families of RNA viruses (reoviruses, togaviruses, flaviviruses, coronaviruses, paramyxoviruses, orthomyxoviruses, rhabdoviruses, bunyaviruses, arenaviruses, retroviruses, picornaviruses, viruses , filoviruses).

3. Virus-cell interaction - This complex process, the results of which may vary. On this basis(final result) can be distinguished 4 types of interaction between viruses and cells:

%/ productive viral infection- this is a type of interaction between a virus and a cell in which Viruses reproduce and the cell dies(for bacteriophages this type of interaction with the cell is called lytic). A productive viral infection underlies acute viral diseases, as well as conditional latent infections, in which not all cells of the affected organ die, but only a part, and the remaining intact cells of this organ compensate for its functions, as a result of which the disease does not manifest itself for some time until decompensation will not occur;

abortive viral infection - This is a type of interaction between a virus and a cell in which virus reproduction does not occur, and the cell gets rid of the virus, its functions are not impaired, since this occurs only during the process of virus reproduction;

latent viral infection - this is a type of virus interaction With cell, in which reproduction of both viruses and cellular components occurs, but the cell does not die; at the same time, cellular syntheses predominate, and therefore the cell retains its functions for quite a long time - this mechanism underlies unconditional latent viral infections;

virus-induced transformations - This is a type of interaction between a virus and a cell in which cells affected by the virus acquire new properties that were not previously inherent to them. The genome of the virus or part of it is integrated into the genome of the cell, and the viral genes are converted into a group of cellular genes. This viral genome integrated into the host cell chromosome is called provirus, and this state of cells is denoted as virogeny.

For any of the above types of interaction between viruses and cells, processes can be distinguished aimed at delivering the viral nucleic acid into the cell and providing conditions And mechanisms of its replication and implementation of the genetic information contained in it.

Question 39. Features of virus reproduction

1. Periods of productive viral infection

2. Virus replication

3. Broadcast

1.Productive viral infection carried out in 3 periods:

initial period includes the stages of adsorption of the virus on the cell, penetration into the cell, disintegration (deproteinization) or “undressing” of the virus. The viral nucleic acid was delivered to the appropriate cellular structures and, under the action of lysosomal enzymes, the cells were released from the protective protein shells. As a result, a unique biological structure is formed: the infected cell contains 2 genomes (its own and viral) and 1 synthetic apparatus (cellular);

After this it begins second group virus reproduction processes, including average And final periods, during which repression of the cellular and expression of the viral genome occurs. Repression of the cellular genome is ensured by low-molecular-weight regulatory proteins such as histones, synthesized in any cell. During a viral infection, this process intensifies; now the cell is a structure in which the genetic apparatus is represented by the viral genome, and the synthetic apparatus is represented by the synthetic systems of the cell.

2. The further course of events in the cell is directed for viral nucleic acid replication (synthesis of genetic material for new virions) and implementation of the genetic information contained in it (synthesis of protein components for new virions). In DNA-containing viruses, both prokaryotic and eukaryotic cells, viral DNA replication occurs with the participation of cellular DNA-dependent DNA polymerase. In this case, in single-stranded DNA-containing viruses, a complementary the thread is the so-called replicative form, which serves as a template for daughter DNA molecules.

3. Implementation of the genetic information of the virus contained in DNA, happens as follows: with the participation of DNA-dependent RNA polymerase, mRNA is synthesized, which enters the cell's ribosomes, where virus-specific proteins are synthesized. In double-stranded DNA viruses, the genome of which is transcribed in the cytoplasm of the host cell, this is its own genomic protein. Viruses whose genomes are transcribed in the cell nucleus use the cellular DNA-dependent RNA polymerase contained there.

U RNA viruses processes replication their genome, transcription and translation of genetic information are carried out in other ways. Replication of viral RNA, both minus and plus strands, is carried out through the replicative form of RNA (complementary to the original), the synthesis of which is ensured by RNA-dependent RNA polymerase - this is a genomic protein that all RNA-containing viruses have. The replicative form of RNA of minus-strand viruses (plus-strand) not only serves as a template for the synthesis of daughter molecules of viral RNA (minus-strands), but also performs the functions of mRNA, i.e., it goes to ribosomes and ensures the synthesis of viral proteins (broadcast).

U plus-strand For RNA-containing viruses, the translation function is performed by its copies, the synthesis of which is carried out through the replicative form (minus strand) with the participation of viral RNA-dependent RNA polymerases.

Some RNA viruses (reoviruses) have a completely unique transcription mechanism. It is provided by a specific viral enzyme - revertase (reverse transcriptase) and is called reverse transcription. Its essence is that first, on the viral RNA matrix, with the participation of reverse transcription, a transcript is formed, which is a single strand of DNA. On it, with the help of cellular DNA-dependent DNA polymerase, the second strand is synthesized and a double-stranded DNA transcript is formed. From it, in the usual way, through the formation of mRNA, the information of the viral genome is realized.

The result of the described processes of replication, transcription and translation is the formation daughter molecules viral nucleic acid and viral proteins, encoded in the genome of the virus.

After this comes third and final period interaction between virus and cell. From structural components(nucleic acids and proteins) new virions assemble on the membranes of the cytoplasmic reticulum of the cell. A cell whose genome has been repressed (suppressed) usually dies. Newly formed virions passively(as a result of cell death) or actively(by budding) leave the cell and end up in its environment.

Thus, synthesis of viral nucleic acids and proteins and assembly of new virions occur in a certain sequence (separated in time) and in different cell structures (separated in space), and therefore the method of viral reproduction was called disjunctive(disunited). During an abortive viral infection, the process of interaction between the virus and the cell is interrupted for one reason or another before the suppression of the cellular genome occurs. Obviously, in this case, the genetic information of the virus will not be implemented and the virus will not reproduce, and the cell retains its functions unchanged.

During a latent viral infection, both genomes function simultaneously in the cell, and during virus-induced transformations, the viral genome becomes part of the cellular genome, functions and is inherited together with it.

Question 40. Cultivation of viruses in tissue cultures

1. Tissue culture characteristics

2. Cytopathic effect of viruses

1.For cultivating viruses use a number of methods. This cultivation in the body of experimental animals, developing chicken vibrios and tissue cultures (usually embryonic tissue or tumor cells). To grow tissue culture cells, multicomponent nutrient media are used (medium 199, Eagle's medium, etc.). They contain an indicator to measure the pH of the medium and antibiotics to suppress possible bacterial contamination.

Tissue culture can be worried, in which cell viability can be maintained only temporarily, and growing, in which cells not only maintain vital activity, but also actively divide.

IN rollerball In cultures, tissue cells are fixed on a dense base (glass) - often in one layer (single-layer), and Vsuspended- suspended in a liquid medium. Based on the number of passages maintained by a growing tissue culture, Among them there are:

primary(primary trypsinized) tissue cultures that can withstand no more than 5-10 passages;

semi-leaf tissue cultures that are maintained for no more than 100 generations;

intertwined tissue cultures that are maintained indefinitely V numerous generations.

The most commonly used are single-layer primary-grafted and continuous tissue cultures.

2. The reproduction of viruses in tissue culture can be judged according to cytopathic action (CPE):

Cell destruction;

Changes in their morphology;

Formation of multi-core simplastov or syncytia as a result of cell fusion.

In tissue culture cells, when viruses multiply, inclusions can form - structures that are not characteristic of normal cells.

Inclusions are revealed in stained Romanovsky-Giemsa smears from infected cells. They are eosinophilic And basophilic.

By location in the celldistinguish:

Cytoplasmic;

Nuclear;

Mixed inclusions.

Characteristic nuclear inclusions form in cells infected with herpes viruses (Cowdry bodies), cytomegaly and polyomas, adenoviruses, and cytoplasmic inclusions - smallpox viruses (Guarnieri and Paschen bodies), rabies (Babes Negri bodies) and etc.

The reproduction of viruses in tissue culture can also be judged using the plaque method (negative colonies). When viruses are cultivated in a cell monolayer under an agar coating, mono-soma destruction zones- so called sterile spots, or plaques. This makes it possible not only to determine the number of virions in 1 ml of medium (it is believed that one plaque is the offspring of one virion), but also to differentiate viruses from each other according to the phenomenon of plaque formation.

The next method to judge the reproduction of viruses (only hemagglutinating ones) in tissue culture can be considered hemadsorption reaction. When cultivating viruses that have hemaggluting activity, Excessive synthesis of hemagglutinins may occur. These molecules are expressed on the surface of tissue culture cells, and the tissue culture cells acquire the ability to adsorb red blood cells to themselves - phenomenon of hemadsorption. Hemagglutinin molecules also accumulate in the culture medium, this leads to the fact that the culture liquid (new virions accumulate in it) acquires ability to cause hemagglutination.

The most common method for assessing viral propagation in tissue culture is "color test" method. When breeding in nutrient medium with an uninfected indicator

tissue culture cells, due to the formation of acidic metabolic products, it changes its color. When the virus reproduces, normal cell metabolism is disrupted, acidic products are not formed, and the medium retains its original color.

Question 41. Mechanisms of antiviral defense of the macroorganism

/. Nonspecific mechanisms

2. Specific mechanisms

3. Interferons

1. Existence of viruses in 2 (extracellular And intracellular) forms predetermineAnd Features of immunity during viral infections. IN The same nonspecific and specific mechanisms of antimicrobial resistance apply to extracellular viruses as to bacteria. Cellular unresponsiveness - one of nonspecific protective factors. It is conditioned absence of receptors on cells for viruses, making them immune to viral infection. This group of protective factors includes feverish reaction and excretory mechanisms (sneezing, coughing, etc.). In protection against extracellular virus participate:

Complement system;

Properdine system;

NK cells (natural killer cells);

Viral inhibitors.

Phagocytic defense mechanism ineffective V against an extracellular virus, but enough active against cells already infected with the virus. Expression of such viral proteins on the surface makes them an object of macrophage phagocytosis. Since viruses are a complex of antigens, when they enter the body, an immune response develops and specific defense mechanisms are formed - antibodies and effector cells.

2. Antibodiesact only on extracellular virus, preventing its interaction with the cells of the body and are ineffective against intracellular viruses. Some viruses (influenza virus, adenoviruses) are inaccessible to antibodies circulating in the blood serum and are able to persist in the human body for quite a long time, sometimes for life.

During viral infections, antibodies of the IgG and IgM classes, as well as secretory antibodies of the IgA class, are produced. The latter provide local immunity to the mucous membranes at the entrance gate, which can be of decisive importance in the development of viral infections of the gastrointestinal tract and respiratory tract. Antibodies of the IgM class appear on the 3-5th day of illness and disappear after a few weeks, so their presence in the patient’s serum reflects acute or freshly transferred infection. Immunoglobulins G appear later and persist longer than immunoglobulins M. They are detected only 1-2 weeks after the onset of the disease and circulate in the blood for a long time, thereby providing protection against re-infection.

Even more important role than humoral immunity, plays a role in all viral infections cellular immunity, which is due to the fact that virus-infected cells become targets for cytolytic actions of T-killers. Among other things, a feature of the interaction of viruses with the immune system is the ability of some of them (the so-called lymphotropic viruses) directly attack the cells themselves immune system, which leads to the development immunodeficiency states.

All of the listed "protection mechanisms (excluding phagocytosis of infected cells) are active only against extracellular virus. Once in the cell, virions become inaccessible to antibodies, complement, or other defense mechanisms. To protect against intracellular virus, during evolution, cells acquired the ability produce a special protein - interferon.

3. Interferon - This a natural protein that has antiviral activity against intracellular forms of the virus. He disrupts mRNA translation on the ribosomes of cells infected with the virus, which leads to the cessation of viral protein synthesis. Based on this universal mechanism of action, interferon suppresses the reproduction of any viruses, i.e., it does not have specificity, the specificity is interferon. It is specific in nature, i.e. human interferon inhibits the reproduction of viruses in human cells, mouse interferon inhibits the reproduction of viruses, etc.

Interferon has antitumor effect, which is indirect evidence of the role of viruses in the occurrence of tumors. The formation of interferon in the cell begins within 2 hours after infection with the virus, i.e. much earlier than its reproduction, and is ahead of the mechanism antibody formation. Interferon is produced by any cells but its most active producers are leukocytes and lymphocytes. Currently, methods genetic engineering bacteria (Escherichia coli) were created into whose genome genes (or copies thereof) responsible for the synthesis of interferon in leukocytes were introduced. The genetically engineered interferon obtained in this way is widely used for the treatment and passive prevention of viral infections and certain types of tumors. IN last years a wide range of drugs has been developed - inducers of endogenous interferon. Their use is preferable to the introduction exogenous interferon. Thus, interferon is one of the important factors of antiviral immunity, but unlike antibodies or effector cells, it provides not protein, but genetic homeostasis.

Question 42. Viral infections and methods of their diagnosis

1. Human viral infections

2. Laboratory diagnosis of viral infections

1.Currently viral infections make up the predominant part of human infectious pathology. The most common among them remain acute respiratory infections (ARVI) and other viral infections transmitted by airborne droplets, the causative agents of which belong to completely different families, most often these are RNA-containing viruses (influenza virus A, B, C, mumps virus, parainfluenza viruses, measles, rhinoviruses, etc.).

No less common are intestinal viral infectious diseases caused by viruses also belonging to various families of RNA and DNA viruses (enteroviruses, hepatitis A virus, rotaviruses, calicinoviruses, etc.).

Viral infectious diseases such as viral hepatitis, especially hepatitis B, transmitted transmissibly and sexually. Their causative agents - hepatitis viruses A, B, C, D, E, G, TT - belong to different taxonomic groups (picornaviruses, hepadnaviruses, etc.), have different transmission mechanisms, but all have tropism for liver cells.

One of the most famous viral infections is HIV infection (often called AIDS - acquired immunodeficiency syndrome, which is its inevitable outcome). Human immunodeficiency virus (HIV) - causative agent of HIV infection - belongs to the family of RNA viruses Retroviridae lentivirus genus.

Most of them - RNA containing They belong to the Toga-, Flavi-, and Bunyavirus families and are causative agents of encephalitis and hemorrhagic fevers. The causative agents of severe forms of hemorrhagic fevers (Ebola fever, Marburg fever, etc.) are phylo- and adenoviruses. But the vector-borne route of infection for these infectious diseases is not the only one. The above infections are mostly endemic diseases, but severe outbreaks of some of these diseases (Crimean hemorrhagic fever, West Nile fever) have occurred in Rostov and Volgograd regions summer 1999

In addition to human infectious pathology, the role of viruses in the development of some animal and human tumors has been proven. (oncogenic, or oncoviruses). Among the known viruses that have an oncogenic effect, there are representatives of both DNA-containing (from the family of papovaviruses, herpesviruses, adenoviruses, poxviruses) and RNA-containing viruses (from the family of retroviruses, genus picornoviruses).

2. For laboratory diagnosis of viral infections Various methods are used.

Virological examination (light microscopy) allows you to detect characteristic viral inclusions, and electron microscopy - the virions themselves and, based on their structural features, diagnose the corresponding infection (for example, rotavirus).

Virological research aimed at isolating the virus and identifying it. Viruses are isolated by infecting laboratory animals, chicken embryos, or tissue cultures.

Primary identification of the isolated virus to the family level can be done using:

Nucleic acid type definitions (test with bromodeoxyuridone);

Features of its structure (electron microscopy);

Virion size (filtration through membrane filters with pores with a diameter of 50 and 100 nm);

Presence of a supercapsid shell (test with ether);

Hemagglutinins (hemagglutination reaction);

Type of symmetry nucleocapsid(electron microscopy).

The results are assessed by inoculating the tissue culture with the appropriately treated sample and then recording the inoculation results using the color filtration test method. Essential for the identification of viruses (to genus, species, within species) is also the study of their antigenic structure, which is held in virus neutralization reactions with appropriate immune sera. The essence of this reaction is that after treatment with homologous antibodies, the virus loses its biological activity (neutralized) and the host cell develops in the same way as one not infected with the virus. This is judged by the absence of a cytopathic effect, a color test, the results of the hemagglutination inhibition reaction (HIT), the absence of changes during infection of chicken embryos, and the survival of sensitive animals.

Virological research- This "gold standard" virology and should be carried out in a specialized virology laboratory. It is currently in use

practically only in conditions of an epidemic outbreak of a particular viral infectious disease.

They are widely used for diagnosing viral infections. immunodiagnostic methods (serodiagnosis and immunoindication). They are realized in a wide variety of immune reactions:

Radioisotope immunoassay (RIA);

Enzyme-linked immunosorbent assay (ELISA);

Immunofluorescence reaction (REEF);

Complement fixation reaction (CFR);

Passive hemagglutination reaction (RPHA);

Hemagglutination inhibition reactions (HAI), etc.

When using methods serodiagnosis is mandatory study of paired sera. Wherein 4-fold increase in antibody titer in the second serum in most cases it serves as an indicator of ongoing or recent infection. When examining one serum taken in the acute stage of the disease, the detection of antibodies of the class IgM, indicating an acute infection.

A great achievement of modern virology is the introduction into practice of diagnosing viral infections molecular genetic methods(DNA probing, polymerase chain reaction - PCR). First of all, they are used to identify persistent viruses found in clinical material that are difficult to detect or undetectable by other methods.

Question 43. Prevention and treatment of viral infections

1. Methods for preventing viral infections

2. Antiviral chemotherapeutic agents

1. For active artificial prevention of viral infections. V including planned widely used live viral vaccines. They stimulate resistance at the entry point of infection, the formation of antibodies and effector cells, as well as the synthesis of interferon. Main types of live viral vaccines:

Flu, measles;

Poliomyelitis (Seibina-Smorodintseva-Chumakova);

Mumps, against measles rubella;

Antirabies, against yellow fever;

Genetically engineered vaccine against hepatitis B - Engerix V. To prevent viral infections are used and killed vaccines:

Against tick-borne encephalitis;

Omsk hemorrhagic fever;

Poliomyelitis (Salka);

Hepatitis A (Harvix 1440);

Anti-rabies (HDSV, Pasteur Merieu);

And also chemical flu

For passive prevention and immunotherapy proposed the following antibody drugs:

Anti-influenza gamma globulin;

Antirabies gamma globulin;

Anti-measles gamma globulin for children under 2 years of age (in outbreaks) and for weakened older children;

Anti-influenza serum with sulfonamides.

A universal remedy passive prevention of viral infections are interferon and inducers of endogenous interferon.

2. Most known chemotherapy drugs do not have antiviral activity, since the mechanism of action of most of them is based on the suppression of microbial metabolism, and viruses do not have their own metabolic systems.

Antibiotics and sulfonamides for viral infections are used only for the purpose prevention bacterial complications. However, they are currently being developed and applied chemotherapeutic agents with antiviral activity.

First group - abnormal nucleosides. In structure, they are close to the nucleotides of viral nucleic acids, but, included in the composition of the nucleic acid, they do not ensure its normal functioning. These drugs include azidothymidine, a drug active against the human immunodeficiency virus (HIV infection). The disadvantage of these drugs is their high toxicity to the cells of the macroorganism.

The second group of drugs disrupts processes virus absorption on cells. They are less toxic, highly selective and very promising. These are thiosemicarbozone and its derivatives, acyclovir (Zovirax) - herpes infection, rimantadine and its derivatives - influenza A, etc.

Interferon is a universal means of therapy, as well as prevention, of viral infections.

Question 44. Bacteriophages

1. The concept of bacteriophages

2. Classification of bacteriophages

3. Diagnostic and therapeutic role of phages

1. Bacteriophages (phages) - This viruses that infect bacterial cells (as a host cell). Phage virions consist of a head containing the viral nucleic acid and a more or less pronounced appendage. The nucleocapsid of the phage head has a cubic type of symmetry, and the process is of a spiral type, i.e. bacteriophages have mixed type nucleocapsid symmetry.

Most phages contain circular double-stranded DNA, and only a few contain RNA or single-stranded DNA. Phages, like other viruses, have antigenic properties and contain group-specific (based on which they are divided into serotypes) and type-specific antigens. Sera containing antibodies to these antigens (antiphage sera) neutralize the lytic activity of phages. The interaction of a bacteriophage with a cell occurs in accordance with the main types of interaction characteristic of all viruses - productive (lytic), abortive viral and latent (lysogeny, virogeny) infection, as well as virus-induced transformation.

By the nature of phage interactionWith cell all bacteriophages are divided:

On virulent (lytic), causing productive infection and lysis of the bacterial cell;

moderate, causing latent infection and association of the viral genome with the bacterial chromosome. Temperate phages, in contrast to virulence, do not cause bacterial cell death and when interacting with it, they transform into a non-infectious form of phage called prophage. Prophage - a phage genome associated with a bacterial chromosome. The prophage, which has become part of the cell's chromosome, replicates synchronously with the bacterial genome during its reproduction, without causing its lysis, and is inherited from cell to cell in an unlimited number of generations. Bacterial cells containing a prophage on their chromosome are called lysogenic. A prophage in lysogenic bacteria can spontaneously or under the influence of various induced agents transform into vegetative phage. As a result of this transformation bacterial cell lyses and produces new phage particles. During lysogenization bacterial cells can additionally acquire new characteristics determined by the genome of the virus. This phenomenon is change in the properties of microorganisms under the influence of a prophage - called phage, or lysogenic, conversion(manifestation of virus-induced transformation).

Temperate phages incapable no way transition from prophage to vegetative phage(to form mature phage particles), are called defective, more often this occurs as a result of a disruption in the assembly stage of viral particles. Some temperate phages are called transducing, since with their help one of the mechanisms of genetic recombination in bacteria is carried out - transduction. Such phages can be used, in particular, in genetic engineering as vectors for producing recombinant DNA and/or preparing recombinant (genetically engineered) vaccines.

2. Phage specificity served as the basis for naming them according to the species and generic names of bacteria sensitive to them. For example, phages that lyse streptococci are called streptococcal, phages that lyse cholera vibrios are called cholera, and staphylococci are called staphylococcal. Based on specificity allocate polyvalent bacteriophages that lyse cultures of one family or genus of bacteria, monovalent (monophages) - lysing cultures of only one type of bacteria, and also characterized by the highest specificity - typical bacteriophages capable of causing lysis only of certain types (variants) of a bacterial culture within a bacterial species.

Sets of such type-specific phages are used to differentiate bacteria within a species - this method of phage typing of bacteria. Using this method, it is possible to establish the source and routes of transmission of an infectious disease, i.e., to conduct its epidemiological analysis, since it allows comparison of phagotypes (phageware) pure cultures of bacteria isolated during a bacteriological study from the patient and from people around him - possible bacteria carriers.

Proteins, unlike nucleic acids,
1) participate in the formation of the plasma membrane
2) are part of chromosomes
3) are accelerators of chemical reactions
4) perform a transport function
5) perform a protective function
6) transfer hereditary information from nucleus to ribosome

This is a creditable job! There are a lot of questions... Help, please! I only threw half of it here. Answer please! Prokaryotes, unlike eukaryotes, have

Select one answer: a. mitochondria and plastids b. plasma membrane c. nuclear substance without shell d. many large lysosomes participate in the entry and movement of substances in the cell Select one or more answers: a. endoplasmic reticulum b. ribosomes c. liquid part of the cytoplasm d. plasma membrane e. Centrioles of the cell center Ribosomes are Select one answer: a. two membrane cylinders b. round membranous bodies c. microtubule complex d. two non-membrane subunits. A plant cell, unlike an animal cell, has Select one answer: a. mitochondria b. plastids c. plasma membrane d. Golgi apparatus Large molecules of biopolymers enter the cell through the membrane Select one answer: a. by pinocytosis b. by osmosis c. by phagocytosis d. by diffusion In case of violation of tertiary and quaternary structure protein molecules in the cell cease to function Select one answer: a. enzymes b. carbohydrates c. ATP d. lipids Question text

What is the relationship between plastic and energy metabolism

Select one answer: a. energy metabolism supplies oxygen to plastic b. plastic metabolism supplies organic substances for energy c. plastic metabolism supplies ATP molecules for energy d. plastic metabolism supplies minerals for energy

How many ATP molecules are stored during glycolysis?

Select one answer: a. 38 b. 36 c. 4 d. 2

The reactions of the dark phase of photosynthesis involve

Select one answer: a. molecular oxygen, chlorophyll and DNA b. carbon dioxide, ATP and NADPH2 c. water, hydrogen and tRNA d. carbon monoxide, atomic oxygen and NADP+

The similarity between chemosynthesis and photosynthesis is that in both processes

Select one answer: a. for education organic matter solar energy is used b. the energy released during oxidation is used for the formation of organic substances inorganic substances c. organic substances are formed from inorganic substances d. the same metabolic products are formed

Information about the sequence of amino acids in a protein molecule is copied in the nucleus from DNA molecule to molecule

Select one answer: a. rRNA b. mRNA c. ATP d. tRNA Which sequence correctly reflects the path of implementation of genetic information Select one answer: a. trait --> protein --> mRNA --> gene --> DNA b. gene --> DNA --> trait --> protein c. gene --> mRNA --> protein --> trait d. mRNA --> gene --> protein --> trait

The entire set of chemical reactions in a cell is called

Select one answer: a. fermentation b. metabolism c. chemosynthesis d. photosynthesis

Biological meaning heterotrophic nutrition is

Select one answer: a. consumption is not organic compounds b. synthesis of ADP and ATP c. receiving building materials and energy for cells d. synthesis of organic compounds from inorganic

All living organisms in the process of life use energy, which is stored in organic substances created from inorganic

Select one answer: a. plants b. animals c. mushrooms d. viruses

During the process of plastic exchange

Select one answer: a. more complex carbohydrates are synthesized from less complex ones b. fats are converted to glycerol and fatty acids c. proteins are oxidized to form carbon dioxide, water, nitrogen-containing substances d. energy is released and ATP is synthesized

The principle of complementarity underlies interaction

Select one answer: a. nucleotides and the formation of a double-stranded DNA molecule b. amino acids and formation of the primary protein structure c. glucose and the formation of a fiber polysaccharide molecule d. glycerol and fatty acids and the formation of a fat molecule

The importance of energy metabolism in cellular metabolism is that it provides synthesis reactions

Select one answer: a. nucleic acids b. vitamins c. enzymes d. ATP molecules

The enzymatic breakdown of glucose without oxygen is

Select one answer: a. plastic exchange b. glycolysis c. preparatory stage of exchange d. biological oxidation

The breakdown of lipids to glycerol and fatty acids occurs in

Select one answer: a. oxygen stage of energy metabolism b. process of glycolysis c. during plastic exchange d. preparatory stage of energy metabolism

Option 1 1. Indicate an example of the biocenotic level of organization of life A) May lily of the valley B) School of cod C) Nucleic acid D) Pine forest 2.

The largest systematic unit A) Kingdom B) Division C) Class D) Family 3. The cell of A) Fungi B) Bacteria C) Cyanobacteria D) Viruses is considered eukaryotic 4. The nitrogenous base is adenine, ribose and three residues phosphoric acid are part of A) DNA B) RNA C) ATP D) protein 5. Ribosomes are A) A complex of microtubules B) A complex of two round membrane bodies C) Two membrane cylinders D) Two non-membrane mushroom-shaped subunits 6. A bacterial cell, like plant cell has A) Nucleus B) Golgi complex C) Endoplasmic reticulum D) Cytoplasm 7. Organelle in which the oxidation of organic substances to carbon dioxide and water occurs A) Mitochondria B) Chloroplast C) Ribosome D) Golgi complex. 8. Chloroplasts in the cell do not perform the function of A) Carbohydrate synthesis B) ATP synthesis C) Absorption of solar energy D) Glycolysis 9. Hydrogen bonds between CO and NH groups in the protein molecule give it a spiral shape, which is characteristic of the structure A) Primary B ) Secondary B) Tertiary D) Quaternary 10. Unlike tRNA, mRNA molecules A) Deliver amino acids to the site of protein synthesis B) Serve as a template for tRNA synthesis C) Deliver hereditary information about the primary structure of the protein from the nucleus to the ribosome D) transfer enzymes to the site assembly of protein molecules. 11. The main source of energy in the cell A) Vitamins B) Enzymes C) Fats D) Carbohydrates 12. The process of primary synthesis of glucose occurs A) In the nucleus B) In chloroplasts C) Ribosomes D) Lysosomes 13. The source of oxygen released by cells during photosynthesis , is A) Water B) Glucose C) Ribose D) Starch 14. How many cells and with what set of chromosomes are formed after meiosis? 15. The divergence of chromatids to the poles of the cell occurs in A) Anaphase B) Telophase C) Prophase D) Metaphase 16. Biological meaning of mitosis. 17. Advantages of asexual reproduction.

36. Proteins, unlike nucleic acids,

1) participate in the formation of the plasma membrane

2) are part of chromosomes

3) participate in humoral regulation

4) carry out a transport function

5) perform a protective function

6) transfer hereditary information from the nucleus to the ribosome

37. In the human nervous system, interneurons transmit nerve impulses

1) from the motor neuron to the brain

2) from the working organ to the spinal cord

3) from the spinal cord to the brain

4) from sensory neurons to working organs

5) from sensory neurons to motor neurons

6) from the brain to motor neurons

38. What are the essential features of an ecosystem?

1) high number of consumer species of the third order

2) the presence of a circulation of substances and energy flow

3) the presence of a common population of different species

4) uneven distribution of individuals of the same species

5) the presence of producers, consumers and destroyers

6) relationship between abiotic and biotic components

When completing tasks 39 – 43, for each position given in the first column, select the corresponding position from the second column. Use arrows to indicate the correct matches.

39. Establish a correspondence between the sign of an animal and the class for which it is characteristic.

SIGN OF AN ANIMAL	CLASS
A) pulmonary and cutaneous breathing	1) Amphibians
B) external fertilization	2) Reptiles
B) dry skin, without glands
D) postembryonic development with transformation
D) reproduction and development occur on land
E) fertilized eggs with large

40. Establish a correspondence between the gland in the human body and its type.

GLAND	TYPE OF GLAND
A) dairy	1) internal secretion
B) thyroid	2) external secretion
B) liver
D) sweat
D) pituitary gland
E) adrenal glands

41. Establish a correspondence between the characteristics of energy metabolism and its stage.

CHARACTERISTIC	ENERGY EXCHANGE STAGE
A) occurs under anaerobic conditions	1) glycolysis
B) occurs in mitochondria	2) oxygen oxidation
B) lactic acid is formed
D) pyruvic acid is formed
D) 36 ATP molecules are synthesized

42. Establish a correspondence between the characteristics of natural selection and its form.

CHARACTERISTIC	SELECTION FORM
A) preserves the average value of the characteristic	1) driving
B) promotes adaptation to changed environmental conditions	2) stabilizing
C) retains individuals with a trait that deviates from its average value
D) helps to increase the diversity of organisms
D) contributes to the preservation of species characteristics

43. Establish a correspondence between natural and artificial ecosystems and their characteristics:

SIGNS OF ECOSYSTEM	TYPES OF ECOSYSTEMS
A) the predominance of monocultures, populations of a few species	1) natural ecosystem
B) works natural selection	2) agrocenosis
C) simplification of relationships between species
D) diversity of species composition
D) open cycle of substances
E) a complex network of relationships between organisms
G) the predominance of artificial selection
H) stability, ability for long-term existence

44. Correlate the characteristics of plants with the departments in which they are located:

SIGNS	DEPARTMENTS
A) the gametophyte is represented by a prothallus
B) sporophyte has multiple leaves - fronds	2) ferns
C) attachment organs are absent or rhizoids
D) sporophyte - capsule
D) green threads sprout from the spores - (protonemata)
E) organs of attachment - rhizomes

45. Match the characteristics of insect orders:

SIGNS	DEPARTMENTS
A) the larva and adult feed differently	1) Lepidoptera
B) gnawing type mouthparts	2) Orthoptera
C) the front wings are hard, the hind wings are thin
D) the oral apparatus is transformed into a proboscis
D) direct development
E) a pupa is present in the developmental stage

46. Establish a correspondence between the nature of adaptation and the direction of organic evolution:

DEVICES	DIRECTIONS OF EVOLUTION
A) protective coloring	1) aromorphosis
B) reduction of the toes of ungulates	2) idioadaptation
IN) sexual reproduction
D) fur of mammals
D) dense cuticle on plant leaves
E) the resemblance of some butterflies to plant leaves

When completing tasks 47 – 50, write in correct sequence numbers that indicate biological processes, phenomena, and practical actions.

47. Establish the sequence of processes occurring during meiosis.

1) arrangement of pairs of homologous chromosomes in the equatorial plane

2) conjugation, crossing over of homologous chromosomes

3) divergence of sister chromosomes

4) formation of four haploid nuclei

5) divergence of homologous chromosomes

48. Construct a sequence of translation reactions:

1) addition of an amino acid to tRNA

2) the beginning of the synthesis of the polypeptide chain on the ribosome

3) attachment of mRNA to the ribosome

4) end of protein synthesis

5) lengthening of the polypeptide chain

49. Place in the correct sequence the stages of creating genetically modified organisms:

1) introduction of a gene vector into a bacterial cell

2) selection of cells with an additional gene

3) creating conditions for inheritance and gene expression

4) combining the created gene with a vector

5) obtaining a gene encoding the trait of interest

6) practical use of transformed cells for protein production

50. Arrange the numbers in a sequence corresponding to the order of the sections of the digestive tract

2) stomach

3) esophagus

4) large intestine

5) duodenum

6) oral cavity

7) small intestine

9) cecum

R. Sherbakul, 2014. Requirements for the organization and conduct of the school stage of the All-Russian Olympiad for schoolchildren in general education subjects on the territory of the Sherbakul municipal district in the 2014-2015 academic year
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Proteins, unlike nucleic acids, 1. participate in the formation of the plasma membrane 2. are part of chromosomes 3. are accelerators of chemical reactions 4. perform a transport function 5. perform a protective function 6. transfer hereditary information from the nucleus to ribosomes

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135! tRNA also performs a transport function in protein biosynthesis. And in 6 this function is performed by tRNA

Nucleic acids as opposed to proteins. Chemical composition and structure of nucleic acids. Participation in protein biosynthesis. Proteins, as opposed to nucleic acids

R. Sherbakul, 2014. Requirements for the organization and conduct of the school stage of the All-Russian Olympiad for schoolchildren in general education subjects on the territory of the Sherbakul municipal district in the 2014-2015 academic year

Entrance test programs (bachelor's degree) entrance tests in general education subjects. Evaluation criteria (for tests conducted by the university independently) Biology (

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