Decreased protein synthesis. Protein metabolism disorders
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Ministry of Health of the Kaluga Region
State Autonomous Educational Institution of Secondary Professional Education "Kaluga Basic Medical College"
Abstract on the topic:
Protein biosynthesis disorders. Their consequences.
Students of the group: Fts021
Olga Prosyanova
Teacher: Safonova V.M.
Kaluga 2014
protein inhibitor amino acid poison
4. ATP deficiency
1. Violations of the structure of genes encoding information about the structure of proteins (mutations)
The precise operation of all matrix biosyntheses - replication, transcription and translation - ensures the copying of the genome and the reproduction of the phenotypic characteristics of the organism over generations, i.e. heredity. However, biological evolution and natural selection possible only in the presence of genetic variability. It has been established that the genome constantly undergoes various changes. Despite the effectiveness of DNA correction and repair mechanisms, some damage or errors in DNA remain. Changes in the sequence of purine or pyrimidine bases in a gene that are not corrected by repair enzymes are called "mutations". Some of them remain in the somatic cells in which they originated, while others are found in germ cells, are inherited and can manifest themselves in the phenotype of the offspring as a hereditary disease.
A gene or parts of genes can move from one place on a chromosome to another. These mobile elements or DNA fragments are called transposons and retrotransposons.
Transposons - sections of DNA that are removed from one locus of a chromosome and inserted into another locus of the same or a different chromosome. Retrotransposons do not leave their original position in the DNA molecule, but can be copied, and the copies are inserted, like transposons, into a new site. By inserting themselves into genes or areas near genes, they can cause mutations and change their expression.
The genome of eukaryotes also undergoes changes when infected with DNA or RNA viruses, which introduce their genetic material into the DNA of host cells.
2. Poisons and specific inhibitors of multienzyme complexes that ensure the processes of transcription, translation and post-translational modification of proteins
Inhibitors of protein biosynthesis can be various substances, including antibiotics, toxins, alkaloids, antimetabolites (analogs) of structural units of nucleic acids, etc. They are widely used in biochemical research as tools for revealing the mechanism of individual stages of protein biosynthesis, since it turned out that among them it is possible select those that selectively inhibit specific phases of protein synthesis. Antibiotics are substances synthesized by microorganisms, mold, fungi, higher plants, animal tissues during their life processes, and also obtained synthetically. They are characterized by bacteriostatic or bactericidal effect. Antibiotics that interact with DNA disrupt its template functions and inhibit replication or transcription, or both. Antitumor antibiotics interact almost equally with the DNA of both tumor and normal cells, since they do not differ in their selectivity.
3. Deficiency of essential amino acids
Amino acids-- organic compounds, the molecule of which simultaneously contains carboxyl and amine groups.
The absence or deficiency of one or more essential amino acids in food products negatively affects general state organism, causes a negative nitrogen balance, disruption of protein synthesis, growth and development processes. Children may develop serious illness - kwashiokor.
Essential amino acids are used to enrich the feed of farm animals in order to increase their productivity, as well as in the form of medicines. Industrial synthesis of some essential amino acids - lysine, methionine, tryptophan - is carried out. Essential amino acids enter the human body along with food products of plant origin. More than 200 different amino acids are synthesized in plants.
Proteins play an important role in the human body. They perform the following functions:
1) catalytic
2) structural
3) protective
4) regulatory
5) transport
Valine is capable of hydrophobic interactions and takes part in stabilizing the tertiary structure of proteins. Valine is used in the synthesis of alkaloids, pantothenic acid, a number of cyclopeptides. The daily requirement for valine is 1.3-3.8 g. A significant amount of valine is found in myoglobin, casein, and elastin.
In terms of chemical properties, leucine is a typical alpha amino acid of the aliphatic series. Leucine is a component of plant and animal proteins. New research indicates that consuming high-quality protein increases levels of leucine, an amino acid that helps a person maintain muscle mass and reduce body fat, promoting weight loss.
Essential amino acids are amino acids that are not synthesized in the human body and must be supplied to the body through food.
Eight of the 20 amino acids are essential:
isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.
When tryptophan is decarboxylated, tryptamine is formed, which increases arterial pressure blood. Violation of tryptophan metabolism leads to confusion, and is also an indicator of diseases such as tuberculosis, cancer, diabetes.
Lack of methionine in food leads to growth retardation, disruption of the synthesis of proteins and many biologically active compounds. Methionine is found in many foods (in milk, in particular in milk protein - casein).
4. ATP deficiency
The main source of energy for the cell is nutrients: carbohydrates, fats and proteins, which are oxidized with the help of oxygen. Almost all carbohydrates, before reaching the cells of the body, are converted into glucose thanks to the work of the gastrointestinal tract and liver. Along with carbohydrates, proteins are also broken down into amino acids and lipids into fatty acids. In the cell, nutrients are oxidized under the influence of oxygen and with the participation of enzymes that control energy release reactions and its utilization. Almost all oxidative reactions occur in mitochondria, and the released energy is stored in the form of a high-energy compound - ATP. Subsequently, it is ATP, and not nutrients, that is used to provide intracellular metabolic processes with energy. When energy is released, ATP donates a phosphate group and becomes adenosine diphosphate. The released energy is used for almost all cellular processes, for example in biosynthesis reactions and muscle contraction. Replenishment of ATP reserves occurs by recombining ADP with a phosphoric acid residue at the expense of energy nutrients. This process is repeated again and again. ATP is constantly used up and stored, which is why it is called the energy currency of the cell.
5. Disturbances in the formation of transport and ribosomal RNA, ribosomal proteins
To carry out the synthesis of nucleic acids, it is necessary to have a sufficient amount of purine and pyrimidine bases, ribose and deoxyribose, as well as high-energy substances in cells. phosphorus compounds. The material for the synthesis of purine and pyrimidine bases are one-carbon fragments of some amino acids and their derivatives (aspartic acid, glycine, serine, glutamine), as well as ammonia and CO 2. Ribose is formed from glucose in the pentose cycle and can later be converted to deoxyribose.
The most pronounced disorders of DNA synthesis occur with deficiency folic acid and vitamin B 12.
With folic acid deficiency, the use of one-carbon amino acid fragments for the synthesis of purine and pyrimidine bases is impaired.
Vitamin B 12 is necessary for the formation of some coenzyme forms of folic acid, the deficiency of which disrupts the conversion of dioxyuridine monophosphate to deoxythymidylate. As a result, thymidine synthesis is disrupted, which limits the formation of new DNA molecules. RNA synthesis is not affected by vitamin B12 and folic acid deficiency. Reduced DNA production inhibits the entry of cells into mitosis due to the lengthening of the synthetic phase of the mitotic cycle. Delayed mitosis leads to a slowdown in cell division, as a result, the process of physiological regeneration in the bone marrow and other rapidly renewing tissues is inhibited. The delay in mitosis is accompanied by an increase in cell size, which is apparently associated with an extension of interphase. These changes are most demonstrably expressed in the hematopoietic tissue of the bone marrow: giant erythroblasts appear - megaloblasts, and when they mature, erythrocytes are formed large sizes- megalocytes. Enlarged myelocytes, metamyelocytes and more mature granulocytes are also found. Giant cells also appear in other tissues: the mucous membrane of the tongue, stomach and intestines, and vagina. Due to the slowdown in regeneration processes, a severe form of anemia (pernicious anemia), leukopenia and thrombocytopenia, and atrophic changes in the mucous membrane of the digestive tract develop.
Vitamin B 12 deficiency in humans occurs during a long-term vegetarian diet, when its absorption in the intestines is impaired due to the cessation of production internal factor Castle in the stomach, with atrophy of its mucosa as a result of damage by autoantibodies. Other reasons for the development of hypovitaminosis B may be: gastrectomy, wide tapeworm infestation, chronic inflammation of the ileum, absence of intestinal mucosa specific receptors, with which the intrinsic factor complex interacts with vitamin B12.
Folic acid deficiency occurs with a long-term absence of green vegetables and animal proteins in food, in children early age when feeding with milk alone (it contains little folic acid). Endogenous deficiency of folic acid can develop due to impaired absorption in the intestine (sprue disease), impaired storage (liver disease), increased consumption (pregnancy, if the initial reserves of the vitamin were reduced), with long-term treatment with certain medications (sulfonamides), with alcoholism.
They are accompanied by a violation of translation with the formation of polypeptide chains in the cytosol, gr. EPS and mitochondria. These disorders occur under the influence of certain pathological factors, for example, antitumor drugs that block protein synthesis in eukaryotes. Changes in ribonucleoprotein complexes of ribosomes, as well as receptors for them, may be accompanied by a decrease in the binding of ribosomes and polysomes to gr. EPS during the formation of secretory proteins. Such newly formed polypeptide chains are quickly destroyed in the cytoplasmic matrix. Pathology of the nucleolar apparatus leads to a decrease in the content of ribosomes in the cytoplasm and suppression of plastic processes in the body. The pathology of mitochondrial ribosomes has some features. Their disturbances are caused by drugs that block protein synthesis in bacteria, for example chloramphenicol, erythromycin, which do not affect the activity of cytoplasmic ribosomes. The consequence of a violation of protein biosynthesis is Gene mutations.
6. Gene mutations
Gene mutations are mutations that result in changes in individual genes and the appearance of new alleles. Gene mutations are associated with changes that occur within a given gene and affect part of it. Usually this is the replacement of nitrogenous bases in DNA, the insertion of extra pairs or the loss of a base pair.
Relationship between mutations and DNA recombination
Of the processes associated with recombination, unequal crossing over most often leads to mutations. It usually occurs in cases where there are several duplicated copies of the original gene on the chromosome that have retained a similar nucleotide sequence. As a result of unequal crossing over, duplication occurs in one of the recombinant chromosomes, and deletion occurs in the other.
Relationship between mutations and DNA repair
Spontaneous DNA damage is quite common and occurs in every cell. To eliminate the consequences of such damage, there are special repair mechanisms (for example, an erroneous section of DNA is cut out and the original one is restored at this place). Mutations occur only when the repair mechanism for some reason does not work or cannot cope with the elimination of damage. Mutations that occur in genes encoding proteins responsible for repair can lead to a multiple increase (mutator effect) or decrease (antimutator effect) in the frequency of mutation of other genes. Thus, mutations in the genes of many enzymes of the excision repair system lead to a sharp increase in the frequency of somatic mutations in humans, and this, in turn, leads to the development of xeroderma pigmentosum and malignant tumors of the integument. Mutations can appear not only during replication, but also during repair - excision repair or post-replicative repair (example: sickle cell anemia).
Literature
1. General biology. A.O. Ruvinsky; Edited by A.O. Ruvinsky. M.: Education, 1993. 544 p.
2. Biology in exam questions and answers/Under. General ed. N.A. Lemezy. 2nd ed. Mn.: BelEn, 1997. 464 p.
3. http://www.xumuk.ru/biologhim/233.html.
4. http://znanija.com/task/1150180.
5. http://www.eurolab.ua/symptoms/disorders/162/.
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Typical disorders of protein metabolism. Inconsistency between protein intake and consumption. Impaired protein breakdown in the gastrointestinal tract and protein content in the blood plasma. Disorder of the final stages of protein catabolism and amino acid metabolism. Lipid metabolism disorders.
The following types of protein synthesis are distinguished depending on its purpose:
regenerative, associated with the processes of physiological and reparative regeneration;
growth synthesis, accompanied by an increase in body weight and size;
stabilizing, associated with the replacement of structural proteins lost during the process of dissimilation, helping to maintain the structural integrity of the body;
functional, associated with the specific activities of various organs (synthesis of hemoglobin, blood plasma proteins, antibodies, hormones and enzymes).
The causes of protein synthesis disorders are:
Lack of sufficient amino acids;
Energy deficiency in cells;
Disorders of neuroendocrine regulation;
Disruption of the processes of transcription or translation of information about the structure of a particular protein encoded in the cell genome.
The most common cause of protein synthesis disorder is lack of amino acids in the body due to:
1) digestive and absorption disorders;
2) low protein content in food;
3) nutrition with incomplete proteins, which lack or contain insignificant amounts of essential amino acids that are not synthesized in the body (Table 12-7).
A complete set of essential amino acids is found in most animal proteins, while plant proteins may lack or contain some of them (for example, corn proteins are low in tryptophan). Flaw in the body at least one of essential amino acids(Table 12-8) leads to a decrease in the synthesis of one or another protein, even with an abundance of others.
Table 12-7. Essential amino acids for humans (according to I.P. Ashmarin, E.P. Karazeeva, 1997)
Table 12-8. Manifestations of essential amino acid deficiency
| Histidine | Dermatitis, anemia, decreased histamine production, mental deterioration |
| Isoleucine | Kidney damage thyroid gland, anemia, hypoproteinemia |
| Leucine | Damage to the kidneys, thyroid gland, hypoproteinemia |
| Methionine (with cysteine) | Obesity, liver necrosis, accelerated atherogenesis, adrenal insufficiency, kidney hemorrhages, choline and adrenaline deficiency |
| Lysine | Anemia, muscular dystrophy, osteoporosis, liver and lung damage, headache, increased sensitivity to noise |
| Phenylalanine with tyrosine | Hypothyroidism, adrenal medulla insufficiency |
| Arginine | Disturbance of spermatogenesis, urea cycle |
End of table. 12-8
Deficiency of essential amino acids in food less often leads to a decrease in protein synthesis, since they can be formed in the body from keto acids, which are products of the metabolism of carbohydrates, fats and proteins.
Lack of keto acids occurs with diabetes mellitus, disruption of the processes of deamination and transamination of amino acids (hypovitaminosis B 6).
Lack of energy sources occurs during hypoxia, the action of uncoupling factors, diabetes mellitus, hypovitaminosis B1, nicotinic acid deficiency, etc. Protein synthesis is an energy-dependent process. The energy of macroergs ATP and GTP is necessary for the activation of amino acids and the formation of peptide bonds (21.9 cal per each peptide bond).
Disorders of neuroendocrine regulation of protein synthesis and breakdown. The nervous system has a direct and indirect effect on protein metabolism. When nervous influences are lost, a disorder of cell trophism occurs 1. Disorders of nervous trophism are an important link in the pathogenesis of any disease. Tissue denervation causes: cessation of their stimulation due to disruption of the release of neurotransmitters; impaired secretion or action of comediators that provide regulation of receptor, membrane and metabolic processes; violation of the release and action of trophogens 2. Confirmation of direct trophic
1 A set of processes that ensure the vital activity of a cell and the maintenance of genetically inherent properties. Nerve fibers regulate not only blood circulation in innervated tissues, but also metabolic, energy and plastic processes in accordance with current needs body.
2 Trophogens are substances of predominantly protein nature that promote the growth, differentiation and vital activity of cells, as well as the preservation of their homeostasis. They are formed in the cells of peripheral organs, in the blood plasma; in neurons, from where they enter innervated tissues using axonal transport; Anabolic hormones can also act as trophogens.
The influence of the nervous system on the metabolism of proteins in cells is the development of atrophic and dystrophic changes in denervated tissues. It has been established that in denervated tissues the process of protein breakdown prevails over synthesis. The indirect influence of the nervous system on protein metabolism is carried out by changing the function of the endocrine glands.
The action of hormones can be anabolic(increasing protein synthesis) and catabolic(increasing protein breakdown in tissues).
Protein synthesis increases under the influence of:
Insulin (provides active transport of many amino acids into cells - especially valine, leucine, isoleucine; increases the rate of DNA transcription in the nucleus; stimulates ribosome assembly and translation; inhibits the use of amino acids in gluconeogenesis, enhances the mitotic activity of insulin-dependent tissues, increasing the synthesis of DNA and RNA);
Somatotropic hormone (GH; the growth effect is mediated by somatomedins produced under its influence in the liver). Another name for somatomedins - insulin-like growth factors - appeared in connection with their ability to reduce blood glucose levels. The main one is somatomedin C, which increases the rate of protein synthesis in all cells of the body. This stimulates the formation of cartilage and muscle tissue. Chondrocytes also have receptors for growth hormone itself, which proves its direct effect on cartilage and bone tissue;
Thyroid hormones in physiological doses: triiodothyronine, binding to receptors in the cell nucleus, acts on the genome and causes increased transcription and translation. As a result, protein synthesis is stimulated in all cells of the body. In addition, thyroid hormones stimulate the action
Sex hormones that have a growth hormone-dependent anabolic effect on protein synthesis; androgens stimulate the formation of proteins in the male genital organs, muscles, skeleton, skin and its derivatives, and to a lesser extent in the kidneys and brain; The action of estrogens is directed mainly to the mammary glands and female genital organs. It should be noted that the anabolic effect of sex hormones does not affect protein synthesis in the liver.
Protein breakdown increases under the influence of:
Thyroid hormones with increased production (hyperthyroidism);
Glucagon (reduces the absorption of amino acids and increases the breakdown of proteins in muscles; activates proteolysis in the liver, and also stimulates gluconeogenesis and ketogenesis from amino acids; inhibits the anabolic effect of growth hormone);
Catecholamines (promote the breakdown of muscle proteins with the mobilization of amino acids and their use by the liver);
Glucocorticoids (increase the synthesis of proteins and nucleic acids in the liver and increase the breakdown of proteins in muscles, skin, bones, lymphoid and adipose tissue with the release of amino acids and their involvement in gluconeogenesis. In addition, they inhibit the transport of amino acids into muscle cells, reducing protein synthesis).
The anabolic effect of hormones is carried out mainly through the activation of certain genes and increased formation various types RNA (messenger, transport, ribosomal), which accelerates protein synthesis; the mechanism of the catabolic action of hormones is associated with an increase in the activity of tissue proteinases.
Reduced synthesis of anabolic hormones, such as growth hormone and thyroid hormones, in childhood leads to growth retardation.
Inactivation of certain factors involved in protein biosynthesis can be caused by certain medications(eg antibiotics) and microbial toxins. It is known that diphtheria toxin inhibits the addition of amino acids to the synthesized polypeptide chain; this effect is eliminated by toxoid.
A stimulating or inhibitory effect on protein synthesis can be caused by changes in the concentration of various ions (primarily Mg 2+), a decrease or increase in ionic strength.
The third form of protein metabolism disorders is disproteinosis, that is, conditions in which the formation of proteins is neither strengthened nor weakened, but perverted. Such situations are extremely varied. These include, for example, various shapes hemoglobinoses,- pathological processes based on the presence in the blood of one or more abnormal hemoglobins, that is, hemoglobins whose synthesis is abnormal, resulting in the formation of a specific protein with completely new properties (reduced tropism for oxygen, reduced solubility, etc.) .
Dysproteinosis, which is of great clinical importance, is amyloidosis.
This pathological process is one of the forms of protein metabolism disorders, in which a special substance is deposited in the interstitial crevices, along the vessels and in their walls, near the membranes of glandular organs - amyloid, having a protein-polysaccharide nature. Amyloid sharply disrupts the function of organs at the site of its deposition and can lead not only to the occurrence of severe disorders in the body associated with the pathology of these organs, but also to the death of the latter.
Amyloidosis is quite widespread. In addition to the not very common primary amyloidosis(the reason for which is not clear) hereditary forms of this pathological process and senile amyloidosis, resulting from age-related changes in people of very advanced age, there is secondary amyloidosis, which is a consequence of long-term inflammatory diseases. The incidence of secondary amyloidosis has been progressively increasing in recent decades.
Changes in organs during amyloidosis were first described in 1844 by the outstanding Viennese pathologist Karl Rokitansky, who called this pathological process greasy degeneration, thereby emphasizing that with it the structure of many internal organs undergoes gross changes. In 1858, Rudolf Virchow identified this disease as an independent nosological form and introduced the term amyloidosis (from the Latin amilum - starch). In 1894, N.P. Kravkov established the chemical structure of amyloid, showing that it is a complex, complex substance, which is a protein associated with a polysaccharide of the type chondroitinsulfuric acid.
Secondary amyloidosis occurs as a result of the presence in the body of chronic inflammatory (especially suppurative) diseases (osteomyelitis, cavernous tuberculosis, syphilis, chronic suppurative processes in the lungs, rheumatoid polyarthritis, etc.). Frequent etiological factors of amyloidosis are also leprosy malaria, chronic dysentery. Amyloidosis itself occurs quite a long time after the onset of the underlying disease. The latent period amyloidosis lasts on average 2-4 years, but can drag on for decades. This is followed by a period, at the beginning of which the symptoms characteristic of the main pathological process prevail, and then dysfunctions of the organ in which amyloid is especially deposited begin to appear. This is usually preceded by a pronounced albuminuria(excretion of protein in the urine), which in some cases long time is the only symptom of the disease, and therefore this stage of amyloidosis is called albuminuric.
The next stage of amyloidosis is characterized by involvement of the liver and adrenal glands in the process, which leads to the development of progressive protein deficiency. accompanied by hypoproteinemic swelling, And vascular hypotension. According to these symptoms, this stage is called edematous-hypotonic.
Then comes the final stage of the process, characterized by an increase renal failure and development uremia(the final stage of renal failure), from which patients die. Since with uremia the amount of residual nitrogen in the blood sharply increases, the terminal phase of amyloidosis is called azotemic.
Deposited in organs amyloid represents in his own way chemical composition glucoprotein, in which protein globulin Connected with mucopolysaccharide - chondroitinsulfuric or mucoitinsulfuric acid. In its structure, amyloid macroscopically looks like a homogeneous substance, but it has a submicroscopic structure, similar to a crystalline one. Amyloid consists of bundles of fibrils, which in humans have a length from 1200 to 5000 nm and a width of 70-140 nm. Amyloid fibrils are ordered (non-crystalline) structure. In addition, spherical particles that are not connected with fibrils were identified in amyloid.
As for the pathogenesis of amyloidosis and the mechanisms of amyloid formation, in general terms they boil down to the following.
It is firmly established that The development of amyloidosis is based on dysproteinosis. It is believed that in chronic suppurative diseases the protein composition of the blood is disrupted, as a result of which it appears a large number of coarse proteins belonging to the group of gamma globulins. This fact, as well as the fact that secondary amyloidosis is a consequence of infectious diseases, suggests the participation of immunological mechanisms in the pathogenesis of this pathological process. This idea is also confirmed by the fact that when amyloidosis is reproduced in an experiment, a pronounced proliferation of elements of the reticuloendothelial system (RES) is observed. A number of precise immunological and histochemical studies have shown that RPE cells undergo certain dynamics during the development of amyloidosis. Initially, with a long-term antigenic stimulus, their proliferation and transformation into plasma cells occurs. Histochemical reactions carried out during this period show the presence in these cells pyroninophilia, indicating an increase in the amount of RNA in them. In time, pyroninophilia coincides with gamma globulinemia. The specified set of changes amounts to pre-amyloid stage, which, with further preservation of the antigenic stimulus, passes into the second - amyloid stage during which the pyroninophilia of cells decreases, which indicates a decrease in the amount of RNA in them. but the number of cells that produce PAS - positive reaction, which detects polysaccharides. Consequently, during this period, increased formation of polysaccharides occurs in plasma cells. Next, these cells begin to secrete amyloid, which is an insoluble compound, into the surrounding tissues. Thus, amyloid is not a product of the combination (outside the vascular bed) of blood globulins, diffused through the vascular wall, with the polysaccharide component, as was previously believed, but is secreted locally by plasma cells. Electron microscopic studies show that accumulation of amyloid precursor - amyloid fibrils - occurs in RPE cells. As the number of these fibrils in the cell increases, its degeneration develops with a complete loss of its own structure. Next, the cell membrane breaks, the fibrils enter the intercellular space, where they combine with the polysaccharide substance secreted by the same cells, resulting in the formation of amyloid.
With amyloidosis, antibodies are detected to the tissues of the organ in which the amyloid is deposited. In this regard, it can be assumed that amyloidosis and autoimmune component.
We must not forget about the possible inclusion in the dynamics of the development of amyloidosis and neurogenic component. This is very convincingly evidenced by observations carried out in besieged and post-siege Leningrad. Statistics show that during the blockade, when, firstly, there was severe starvation, and secondly, a state of extreme nervous tension, the number of cases of amyloidosis was minimal. But after the end of the war, people who survived the blockade experienced a sharp rise in the incidence of amyloidosis, which significantly exceeded the pre-war level.
Since amyloidosis develops only in a relatively small proportion of individuals suffering from chronic inflammatory diseases, a role cannot be ruled out. hereditary factor in its pathogenesis.
2. What are the names of the nuclear structures that store information about the body’s proteins?
3. Which molecule is the matrix (template) for the synthesis of mRNA?
4. What is the name of the process of synthesis of a polypeptide chain of a protein on a ribosome?
5. On which molecule is there a triplet called a codon?
6. On which molecule is there a triplet called an anticodon?
7. By what principle does an anticodon recognize a codon?
8. Where in the cell does the t-RNA+amino acid complex form?
9. What is the name of the first stage of protein biosynthesis?
10. Given a polypeptide chain: -VAL - ARG - ASP - Determine the structure of the corresponding DNA chains.
2.what type of RNA transports amino acids to the site of protein synthesis?
3.what type of RNA transfers hereditary information from the nucleus to the cytoplasm?
4. In which organisms are the processes of transcription and translation not separated in time and space?
5. How many nucleotides of mRNA does the “functional center” of the ribosome include?
6. How many amino acids should be present in the large subunit of the ribosome at the same time?
7.How many genes can prokaryotic mRNA include?
8.How many genes can eukaryotic mRNA include?
9. when the ribosome reaches the STOP codon, it adds a molecule to the last amino acid
10. if there are many ribosomes on one mRNA at the same time, this structure is called
11. energy is used for protein biosynthesis, as for other processes in the cell
energy for reaction
E. Protein monomer
F Group of nucleotides coding for one amino acid
connections
2. DNA triplets
3. Ribosome
4. RNA polymerase
5. Amino acid
it is necessary to correlate the substances and structures involved in protein synthesis with their functions
Where is hereditary information stored? The name of the protein shell of the virus. The second name of nuclear organisms. The second name of viruses - eatersbacteria. What does the cell wall of plants consist of? What cell structure can be smooth and rough? The name of the main substance of the cytoplasm. Which organelle is the center of protein synthesis in the cell? The general name for the processes of phago- and pinocytosis. Name of colorless plastids.
1. The reactions of plastic metabolism in the human body include the process1) transport of nutrients through the digestive canal
2) secretion of sebum by the sebaceous glands
3) protein synthesis in liver cells
4) filtration of blood plasma in the nephron
2. Establish the level organization of the structure of the human auditory analyzer
century, starting from its peripheral part - the ear. In response, write down the corresponding
the corresponding sequence of numbers.
1) receptor hair cells
2) snail
3) inner ear
4) membranous labyrinth
5) organ of Corti
3. Insert into the text “Processes occurring in the human large intestine”
missing terms from the proposed list, using
digital symbols. Write down the numbers of the selected answers in the text, and then
enter the resulting sequence of numbers (according to the text) in the given
Below is the table.
Processes occurring in the human large intestine
In the large intestine, a large amount of ________ is absorbed into the blood (A).
The glands of the large intestine produce a lot of ________ (B) and facilitate,
thus promoting and eliminating undigested food debris.
Bacteria in the large intestine synthesize some ________ (B). Not over-
cooked food remains enter the ________ (D) and are removed from the body.
List of terms
1) mucus
2) water
3) glucose
4) enzyme
5) vitamin
6) rectum
7) cecum
8) pancreas
4. To reactions energy metabolism process in the human body
1) protein synthesis in muscle fibers
2) blood transport of nutrients throughout the body
3) glucose oxidation in brain neurons
4) reabsorption of primary urine in the convoluted tubules of the kidneys
5. Why do doctors recommend including foods containing
What iodine?
1) iodine affects changes in the composition of blood plasma
2) iodine normalizes the activity of the thyroid gland
3) iodine prevents sore throat
4) iodine promotes the synthesis of vitamin C in the body
6. During an athlete’s training, reserves are the first to be used up.
1) vitamins 2) proteins 3) fats 4) carbohydrates
7. The danger of tanning is that
1) skin darkens
2) melanoma may occur
3) excess vitamin D is produced
4) a large amount of blood flows into the expanding vessels of the skin
8. In which part of the digestive canal does absorption mainly occur?
tion of organic matter in food?
1) in the oral cavity 3) in the large intestine
2) in the stomach 4) in the small intestine
9. Establish a level organization of the building visual analyzer human
century, starting from its peripheral section. In response, write down the corresponding
a certain sequence of numbers.
1) eye
2) retina
3) eyeball
4) cones
5) photoreceptors
A long-term and significant decrease in protein synthesis leads to the development of dystrophic and atrophic disorders in various organs and tissues due to insufficient renewal of structural proteins. Regeneration processes slow down. In childhood, growth, physical and mental development are inhibited.
tie. The synthesis of various enzymes and hormones (GH, antidiuretic and thyroid hormones, insulin, etc.) decreases, which leads to endocrinopathies and disruption of other types of metabolism (carbohydrate, water-salt, basal). The content of proteins in the blood serum decreases due to a decrease in their synthesis in hepatocytes. As a result, oncotic pressure in the blood decreases, which contributes to the development of edema. The production of antibodies and other protective proteins decreases and, as a result, the immunological reactivity of the body decreases. To the most pronounced extent, these disorders arise as a result of long-term disruption of the absorption of food proteins in various chronic diseases of the digestive system, as well as during prolonged protein starvation, especially if it is combined with a deficiency of fats and carbohydrates. In the latter case, the use of protein as an energy source increases.
Causes and mechanism of disruption of the synthesis of individual proteins. In most cases, these disorders are hereditary. They are based on the absence in cells of messenger RNA (mRNA), a specific matrix for the synthesis of any particular protein, or a violation of its structure due to a change in the structure of the gene on which it is synthesized. Genetic disorders, for example, the replacement or loss of one nucleotide in a structural gene, lead to the synthesis of an altered protein, often devoid of biological activity.
The formation of abnormal proteins can be caused by deviations from the norm in the structure of mRNA, mutations of transfer RNA (tRNA), as a result of which an inappropriate amino acid is added to it, which will be included in the polypeptide chain during its assembly (for example, during the formation of hemoglobin).
The translation process is complex, occurring with the participation of a number of enzymes, and dysfunction of any of them can lead to the fact that one or another mRNA does not transmit the information encoded in it.
Violation of the synthesis of individual enzyme proteins or structural proteins underlies various hereditary diseases (hemoglobinosis, albinism, phenylketonuria, galactosemia, hemophilia and many others - see section 5.1). Violation of any enzymatic function is most often associated not with the absence of the corresponding protein - enzyme, but with the formation of a pathologically altered inactive product.
Causes, mechanism and consequences of increased breakdown of tissue proteins. Along with synthesis in the cells of the body, protein degradation constantly occurs under the action of proteinases. The renewal of proteins per day in an adult is 1-2% of the total amount of protein in the body and is associated mainly with the degradation of muscle proteins, while 75-80% of the released amino acids are again used for synthesis.
Nitrogen balance- an integral indicator of the general level of protein metabolism, this is the daily difference between nitrogen entering and released from the body,
In a healthy adult, the processes of protein breakdown and synthesis are balanced, i.e. available nitrogen balance. At the same time, daily protein degradation is 30-40 g.
Nitrogen balance can be positive or negative.
Positive nitrogen balance: the intake of nitrogen into the body exceeds its excretion, i.e. protein synthesis prevails over its breakdown. It is noted during tissue regeneration, during the period of recovery after serious illnesses, during pregnancy, in childhood, with hyperproduction of growth hormone, and with polycythemia.
In pathology, protein breakdown may prevail over synthesis and less nitrogen enters the body than is excreted (negative nitrogen balance).
The causes of negative nitrogen balance are: infectious fever; extensive injuries, burns and inflammatory processes; progressive malignant tumor growth, endocrine diseases (diabetes mellitus, hyperthyroidism, hypercortisolism); heavy emotional stress; dehydration, protein starvation, radiation sickness; hypovitaminosis A, C, B 1, B 2, B 6, PP, folic acid deficiency. The mechanism of increased protein breakdown in many of these conditions is the increased production of catabolic hormones.
The consequence of a negative nitrogen balance is degenerative changes in organs, weight loss, and in childhood - retarded growth and mental development.