- Phenotype as a result of the implementation of the genotype in a specific environment.
- Quantitative and qualitative specificity of gene manifestations in signs.
- Interaction ne. allel Genov.
Genome - A combination of genes characteristic of the haploid set of chromosoma of this species. In the fertilization of the genome of parents, the cellular genotype of the zygotes is combined and form.
Genotype - A combination of all organism genes (genetic constitution). From the genotype of zigotes in the process of ontogenesis, many hundreds of various cell phenotypes arise. Separate cell phenotypes form the phenotype of the whole organism. The whole process of life from the formation of zygotes to natural death is controlled by genes. The genotype constantly experiencing an environmental environment, it interacts with the medium, which leads to the formation of all signs and properties of the body.
Phenotype - All signs of the body, forming as a result of the interaction of the genotype and environment. (Johansen - 1803) properties of any organism depend on the genotype and on the medium, therefore the formation of the body is the result of the interaction of genetic factors and factors of the external environment.
For a long time it was believed that in the zygote there are different chromosomes for different cells, but now it is known that there is the same in the zygote genetic informationAs in all cells of this organism. In specialized cells, genes characteristic of cell data functions are operating, and all others - up to 95% are blocked. Each embryonic cell can potentially become any cell of the body, i.e. Specialized in any side - polypotent cells. Each cell cell is capable of differentiating only one way. The direction of specialization is determined by the external environment (chemical environment of chromosomes - cytoplasm). In the earliest stages of embryogenesis, the genotype is already interacting with the medium. The interaction is conveniently viewed by the example of globin genes. Before and after birth, these genes work unequal. In early embryogenesis, the gene is included responsible for the hemoglobin alpha chain (it is active throughout the life), and the gene responsible for the synthesis of beta chains is inactive. But there is a gene responsible for the synthesis of gamma chain. After birth, the beta chain gene begins to work, and the gamma is blocked. These changes are associated with respiratory features. Fetal hemoglobin easily informs air to the embryo.
The phenotypic manifestation of the genotype in the dependence of the environment of the medium varies within the reaction rate. From parents, descendants receive specific types chemical reactions For different environmental conditions. The combination of all chemical reactions will determine metabolism - metabolism. The intensity of metabolism varies widely. Each person has its own characteristics of metabolism, which is transmitted from generation to generation, and obey Mendel's laws. Differences in metabolism are implemented in specific environments at the level of protein synthesis.
Differentiated primrose plants reaction in different conditions ambient. At the usual temperature of 20-25 degrees and normal pressure - red flowers, at elevated temperature or pressure - white flowers. Seeds have the same properties.
Fly - Drozophile has a gene that shapes the closure of the wings on the back. If flies with mutant genes to remove at a temperature of 21-25 degrees, the wings are bent. At a lower temperature, normal wings and only some are bent. The gene determines the synthesis of heat sensitive protein. Therefore, which are suitable after exiting the pupa, at elevated temperatures there is a deformation of the wings.
No signs are inherited. Signs are developing on the basis of the interaction of the genotype and environment. Only genotype is inherited, i.e. The gene set of genes, which determines the norm of the biological response of the body, changing the manifestation and severity of the signs in different conditions of the medium. Thus, the body responds to the properties of the external environment. Sometimes the same gene, depending on the genotype, and on the conditions of the external environment, there is a sign of a different way or changes the completeness of severity.
The degree of manifestation of the phenotype - expressiveb It can be sampled with the degree of severity of the disease in clinical practice. Expressiveness obeys Gauss distribution laws (some in small or medium number). The variability of expressiveness is also based on genetic factors, and environmental factors. Expressiveness is a very important indicator of the phenotypic manifestation of the gene. Quantitatively, its degree is determined using the statistical indicator.
The genetic sign may not even manifest itself in some cases. If the gene is in the genotype, but it does not appear at all - it is penetrated. (Russian scientist Timofeev-Rice 1927). Penetrant - The number of individuals (%) exhibiting this gene in the phenotype, with respect to the number of individuals whose sign could manifest itself. Penetrantiness is peculiar to the manifestation of many genes. The principle is important - "Everything or nothing" - either manifests itself, there is no anyone.
Hereditary pancreatitis - 80%
Hip dislocation - 25%
Vices of eye development
Retinoblastoma - 80%
Otosclerosis - 40%
Kolotokoma - 10%
Hantington's chorea manifests itself in an involuntary head twitching. The limbs gradually progresses and leads to death. It can manifest itself in the early post-magnitude period, in adulthood or not to manifest at all. And expressiveness, and penetrantiness are maintained by natural selection, i.e. Genes controlling pathological signs may have different expressiveness and penetrantity: not all carriers of the gene are ill, and the resulting degree of manifestation will be different. The manifestation or incomplete manifestation of the feature, as well as its absence depends on the medium and from the modifying action of other genes.
1919 Bridges introduced the term gene modifier. Theoretically, any gene can interact with other genes, which means that to show a modifying effect, but some genes are modifiers to a greater extent. They often do not have their own sign, but are able to strengthen or weaken the manifestation of a feature controlled by another genome. In the formation of a trait other than the main genes, and modifying genes are shown.
Brachidactia - may be sharp or minor. In addition to the main gene, there is still a modifier that enhances the effect.
Mammalian coloring - white, black + modifiers.
The gene can act pleotropic (multiple), i.e. indirectly influence different reactions and the development of many signs. Genes can influence other signs at different stages of ontogenesis. If the gene is included in the late ontogenesis, it turns out a minor action. If in the early stages - changes are more significant.
Phenylketanuria. Patients have a mutation that turns off the enzyme - phenylalanine - hydrolase. Therefore, phenylalanine does not turn into tyrosine. As a result, the amount of phenylalanine rises in the blood. If you reveal this pathology early (up to 1 month) and transfer the child to another nutrition, the development is normal, if later is lowered by the size of the brain, mental backwardness, do not develop normally, there is no pigmentation, mental abilities are minimal.
Pleotropy reflects the integration of genes and signs.
A person has a pathological gene, leading to Fanconi syndrome (damage or lack of thumb, vice or lack of radiation, underdevelopment of the kidney, brown pigment stains, a shortage of blood taurus).
There is a gene associated with the X chromosome. Immunity to infections and shortage of bloodthorn.
The dominant gene captured with the X-chromosome - pylonfritis, labyrinth of hearing loss.
Marfani Syndrome - Spider fingers, dislocation of the leather eye, malformations of the heart.
Polymerism. If the genes are located, each in its separate locus, but their interaction is manifested in the same direction - these are polygen. One gene shows a sign slightly. Polygenies complement each other and have a powerful action - a polygenic system occurs - i.e. The system is the result of the action of equally directed genes. The genes are subjected to a significant influence of the main genes, which are more than 50. Many polygenic systems are known.
With diabetes, mental retardation is observed.
Growth, level of intelligence - are determined by polygen systems
Complementation - Phenomenon at which 2 non-allele genes. While in genotype, simultaneously lead to the formation of a new feature. If one of the pair is present - he manifests itself.
An example is the blood group in humans.
Complementation may be dominant and recessive.
In order for a person to have a normal rumor, it is necessary that many genes and dominant and recessive are coordinated. If, at least one gene, it will be homozygoten on recession - the rumor will be weakened.
Epistasis - Such interaction of genes, when the gene of one allelic pair is masked by the action of another allelic pair. This is due to the fact that enzymes catalyze different cell processes when several genes operate on one metabolic pathway. Their action must be agreed in time.
Mechanism: If it turns off, it disguises the action with
B - epistatic gene
C - hypostatic gene
Makusik:
"The ratio between the genotype and the phenotype is, both between the character of man and its reputation: genotype (and character) - inner essence Individual, phenotype (and reputation) - this is how it looks like or seemingly surrounding. "
Lecture number 9.
Variability.
1. Modification variability.
2. Combinative variability.
3. Marriage system.
4. Mutational variability.
One of the signs of life is variability. Any living organism differs from other representatives of the species. Variability - The property of living organisms exist in different forms. Group and individual variability - classification by evolutionary value. The variability implemented by a group of organisms is called group, one organism or the group of its cells is individual.
By the nature of the change in signs and the mechanism:
Phenotypic
Random
Modification
Genothypical
Somatic
Generative (mutational, combinative)
a) gene
b) chromosomal
c) genomic
Modification variability Reflects the change in the phenotype under the influence of environmental factors (strengthening and developing muscle and bone mass in athletes, an increase in erythropoese in the conditions of high mountains and the Far North). Private case of phenotypic variability - fenocopy.. Fenocopy. - caused by the conditions of the external medium, phenotypic modifications that imitate genetic signs. Under the influence of external conditions on a genetically normal organism, signs of a completely different genotype are copied. Daltonism manifestation can occur under the influence of nutrition, a bad mental constitution, increased irritability. A person has a vitiligo disease (1% of people) - a violation of skin pigmentation. The genetic defect is in 30% of those who are ill, in the rest - professional vitiligo (impact on the body of special chemical and poisoning substances). In Germany, two years ago, children were born with entertainment - shortened with lastic hands. It turned out. That the birth of such children happened if the mother took Telidomid (the sedative, shown by pregnant women). As a result, the normal not limited genotype was mutated.
Fenocopies appear in most cases under the action of an external environment in the early stages of embryogenesis, which leads to congenital diseases of developmental deposits. The presence of phenocopuses makes it difficult for diagnosis of diseases.
Somatic variability Not transferred by inheritance.
Combinative variability - The result of independent discrepancies chromosome in the process of meiosis, fertilization, crosslinker with the recombination of genes. In combinative variability, the genes are reconnected, a new individual set of chromosomes occurs, which means that the new genotype and the phenotype occurs. For combinative variability in the system of people, the system of marriages is of great importance. The simplest is the random selection of pairs (pamix). Strictly pamix populations do not exist, because There are limitations: social, religious, individual, economic and others. Therefore, in populations of people there are deviations from PumpMixes in two directions:
1) People who are among themselves in relationship are marked more often than with random selection - inbreeding - inblest (bloodarious marriages).
2) People come into marriage more often with a random selection of steam than with kindred marriage - OUTORS.
Inbrid marriages are of great importance in the medical plan. Because The likelihood that both spouses possess the same recessive genes is much higher if the spouses are among themselves in relationship, especially close. Rodality is natural. From a medical point of view, selective marriages of phenotypic sign are considered close to the genetic effect. If the choice of a marriage partner has an impact on the genotype of the descendant - Assistance marriages. People who are similar to phenotypic, more often marry than with a random selection of couples - positive assistance marriages, if less often - negative. Examples can serve as marriage between deaf-and-and-and-leather, people of high growth, people with the same skin color. Negative assistance marriages between red-haired people.
Georgic marriages often met in the early stages of human development.
3 groups of inbreeding are isolated:
1. Between relatives of the first relationship
2. Correctic marriages of isolated populations
3. Encouraged nearby marriage for social, religious and other considerations.
Incestant (forbidden) marriages between relatives of the first relationship: Mother Son, father-daughter, brother sister. We took place in Egypt, Ptolemyev dynasty. In a number of eastern countries, the genus Ivan Grozny (starting from Ivan Kalita is some such marriages).
Legal restrictions: marriages between cousins, nephews and aunts, nieces and uncles are allowed. Although in some countries there are restrictions. The United States and the UK is an uncle-niece, a half-tech-niece - forbidden. In the US, cousins \u200b\u200bare prohibited, in the UK - allowed.
Corporate marriage in isolated areas (isolates), incl. and religious isolates are inevitable, because otherwise the population is dying.
In large uninsulated populations, nearby marriage is 1% in the city and 3% in the villages, to the secondary. Corporate marriages are encouraged among the Jews in Eastern countries. There are up to 12%.
In the Samarkand region
Uncle-niece 46
Nephew-aunt 14
Cousins \u200b\u200b42.
Incestant 2.
The inbreeding coefficient is the average identical in origin.
USA, Catholics - 0.00009
Israel and Jordan - 0,432
India - 0.32.
Japan - 0.0046.
In India, half of the marriages are between relatives - children's mortality at any sufficiency is 50%.
Genetic effect of nearby marriages: Rare autosomal-refrigerating diseases become ordinary.
The frequency of occurrence of recessive genes compared to marriages concluded between people who are not relatives increases sharply in marriages between relatives.
Mutational variability - The only type of variability, as a result of which new genes may appear, which could not meet before. The change in the genotype occurs and, as a result, the phenotype changes. In accordance with the three levels of the organization of gene material, 3 types of mutations are distinguished: gene, chromosomal and genomic.
Mutation - A sudden hereditary change in a phenotypic feature caused by a sharp structural or functional change.
Gene mutations associated with a change in the internal structure of genes, which turns some alleles to others. Several types of gene mutations at the molecular level can be distinguished:
Replacing couple nucleotide
Deletion
Insert nucleotide
Rearrangement (inversion) of a portion of the gene.
Replacing couple nucleotide . Replacement of purine base to another purin, or one pyrimidine to another pyrimidine - transition. Replacement of purine base for pyrimidine and vice versa - transvessia. When replacing nucleotides in structural genes, a change in the meaning of the gene is changed - arise missens-Mutitation. In this case, one amino acid in the polypeptide is replaced by another. The phenotypic manifestation of mutation depends on the position of amino acids in the polypeptide. When replacing the sequence of CTCs on the Central Council, sickle cell anemia arises. A new polypeptide and hemoglobin has completely different properties. Some missens mutations lead to an enzyme having a high activity in some conditions and mean in other conditions. Because genetic code Deal, then when replacing triplets encoding the same amino acid, mutations are not manifested. Another type of mutation - nonsense - Mutation. With these mutations, when replacing one nucleotide, there are no senseless thrips. The synthesis of the polypeptide stops and the protein has completely different properties.
Test tasks
* Test tasks with multiple answers
1. With mono-librid crossing of the first generation hybrids phenotypically and
gentypically uniformly - the law of Mendel: 1) 1; 2) 2; 3) 3; 4) 4.
2. * Monogererosigot this: 1) AA; 2) AA; 3) AAVA; 4) AAVA; 5) AA; 6) AAVA; 7) AAVB.
3. * Analyzing crossing is: 1) ♀aa× ♂aa; 2) ♀ aa × ♂ aa; 3) ♀aa × ♂aa; 4) ♀ aa × ♂ aa
4. * Possible genotypes of offspring from crossing a comolet (dominant sign) heterozygous cow with horned bull: 1) all BB; 2) BB; 3) BB; 4) all BB; 5) BB.
5. In the analyzing crossing, the hybrid f cross1 C Homozygotype: 1) Dominant; 2) recessive.
6. Crossing two heterozygotes (complete dominance) The phenotype splitting will be observed in the offspring: 1) 9: 3: 3: 1; 2) 1: 1; 3) 3: 1; 4) 1: 2: 1.
7. The combination of genes in the cell: 1) genotype; 2) genome; 3) karyotype; 4) phenotype; 5) Genofund.
8. * The sign is called dominant if: 1) inherits hybrids f1 2) manifests itself in heterozygot; 3) does not appear in heterozygot; 4) Meets most individuals in the population.
9. Fenotype splitting in F2 with incomplete dominance in mono-librid crossing: 1) 9: 3: 3: 1; 2) 1: 1; 3) 3: 1; 4) 1: 2: 1.
10. Gray rabbit wool gray dominates over white. Gray rabbit genotype: 1) AA; 2) AA; 3) aa; 4) av.
11. As a result of the crossing of the plant strawberries (incomplete dominance - red, white and pink fruit color) with AA and AA genotypes Phenotypic ratio of offspring: 1) 1 red: 1 white; 2) 1 red: 1 pink; 3) 1 white:
1 pink; 4) 1 red: 2 pink: 1 white.
12. As a result of crossing chickens (incomplete dominance: Black-blue-white color of plumage) with genotypes AA and AA Phenotypic ratio of offspring: 1) 1 black: 1 white; 2) 3 black: 1 blue; 3) 3 black: 1 white; 4) 1 black: 2 blue: 1 white; 5) 1 blue: 1 white; 6) 3 Blue: 1 white.
13. * Dominant homozygota is: 1) AAVR; 2) AABB; 3) AABB; 4) AABB; 5) AABBCC.
14. Gameta AVDD formed by genotype: 1) AABBCCDD; 2) aabbcdd; 3) aabbccdd; 4) AABBCCDD.
15. * Drozofila black (recessive sign) body and normal wings (dominant sign) - genotype: 1) AAVA; 2) AAVB; 3) AABB; 4) AAVA; 5) AABB; 6) AABB; 7) AABB; 8) AABB.
16. * Rabbit is a shaggy (dominant sign) white (recessive sign) fur - genotype: 1) AABB; 2) AAVB; 3) AABB; 4) AAVA; 5) AABB; 6) AABB; 7) AABB; 8) AABB.
17. * Pea has high plants (dominant sign) and red flowers
(dominant sign) - genotype: 1) AABB; 2) aabb; 3) AABB; 4) AABB; 5) AABB; 6) AABB; 7) AABB.
3.7. Basic patterns of variability
IN polls for repetition and discussion
1. What processes lead to combinative variability?
2. What is the basis of the uniqueness of each living organism at the level of the genotype and phenotype?
3. What environmental factors can activate the mutation process and why?
4. What is the difference between the inheritance of somatic mutations from the generative and what is their importance for the body and the species?
5. What mechanisms for moving mobile elements by genome can you call?
6. Why does human activity increase the mutagenic effect of the environment?
7. What biological significance may have a phenotype transformation without changing the genotype?
8. Why modifications are mostly useful for the body?
Control tasks
1. Phenotype is a totality | |||||
domestic | |||||
the characteristics of the body. Consider | |||||
differences in the phenotype. Express | |||||
assumptions about the reasons for | |||||
phenotypes | |||||
2. Observations for meta | |||||
morphoz frosophila showed: a) | |||||
if in the feed of the larvae of drosophila | |||||
add some silver nitrate, | Fig. 3.98. Variability of horns |
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then yellow individuals are out | |||||
to the homozygosity of them for the dominant gene of gray color of the body (AA); b) In individuals, homozygous in the recessive gene of the desire of wings (BB), at a temperature of 15 ° C, the wings remain similar, and at a temperature of 31 ° C, normal wings grow. What can you say on the basis of these facts about the relationship between the genotype, environment and phenotype? Does these cases happen to transform a recessive gene into the dominant or vice versa?
3. Any sign may vary within certain limits. What is the reaction rate? Give examples of signs of organisms with a wide and narrow reaction rate. What determines the latitude of the reaction rate?
4. Calculate the average value (m) and build a variation curve according to the following data (Table 3.8; 3.9).
Table 3.8.
Variability of the number of tongue flowers in the inflorescence of chrysanthemum
Number of flowers | |||||||||||||||||||||||||
inflorescence | |||||||||||||||||||||||||
The number of inflorescence | |||||||||||||||||||||||||
Table 3.9. |
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The variability of the number of bone rays in the tail fins of Cambals | |||||||||||||||||||||||||
Number of rays | |||||||||||||||||||||||||
finnish | |||||||||||||||||||||||||
Number of individuals | |||||||||||||||||||||||||
5. In the area of \u200b\u200bChernobyl, animal mutants began to appear after the catastrophe at the atomic power plant, people have increased the frequency of diseases of the thyroid cancer. What do these facts indicate? Why in the rivers polluted industrial waste large cities Fish mutants appear with a huge head, without scales, with one eye, devoid of color? Give an explanation to this phenomenon.
Consider | ||||
3.99. Body weight in large |
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cattle, like others |
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animals - a typical number |
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sign. | Development |
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quantitative | signs |
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Fig. 3.99. Two bulls year old | Install |
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ages that occurred from one | what type of variability led |
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father, but grown in different | to change the mass | bodies of these |
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conditions | one of which is |
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chal feed in excess, and the other was fed very poorly.
7. Consider the various forms of the leaves of the grains, (Fig. 3.100), which is a classic example of modification variability. Determine what caused differences in the form of leaves in the plants of the grains of grown in different conditions.
8. Consider changes in the color of the hair of the ermine rabbit under the influence of different temperatures (Fig. 3.101). Determine the type of variability.
Fig. 3.100. Form of leaves
gravist with development in different environments
Fig. 3.101. Changing the color of the Himalayan wool
rabbit under the influence of different temperatures
Laboratory workshop
1. A series of multiple alleles is a drawing of gray spots on clover leaves. Get acquainted with the herbarium of clover leaves and trace the character of the inheritance of the sign of gray spots. The gene that determines this feature is represented by the eight most common alleles. Compare the drawing on the Herbarium Sheet with the figures shown in the diagram (Fig. 3.102) and determine the genotype.
There is incomplete dominance. It is impossible to determine the genotype of only those forms where the paintings of spots defined by two alleles merge or takes full dominance. For example, VBVH IVHVH have the same phenotype, VBVP IVBVB also do not differ phenotypically, since the VFVP dominates the VFVP IVFVL does not distinguate the OVFVF due to the merge of the drawings. Heterozygots CV also do not differ from the dominant homozygotes.
Draw the instances offered to you and determine their genotypes or phenotypic radicals, write down the characters. Make a series of all those who met alleles.
Fig. 3.102. Sewage patterns of gray spots on clover leaves indicating
genotype
(VV - the stain is absent; Vv is a solid ^--like spot; VHVH is a solid high ^--like spot; VBVB - ^--like spot with a gap; VBHvbh - high ^--like spot with a gap; vpvp - ^--like stain in the center ; VFVF is a solid triangular stain based on; VLVL - a solid small triangular spot on the ground
2. Determination of the individual ability of a person to feel the bitter taste of phenylthioma (FTM). With the help of a tweezers, place on the back of the back of the language first the control, and then an experienced strip of filter paper, determine your individual ability (inability) to sense the bitter taste of FTM, i.e. Sign of FTM + or FTM. Make a conclusion about your possible genotype. Having in mind that the sign of FTM + is controlled by the dominant genome (T).
Conditionally considering the student group as a separate population, define the population frequency of the feature of FTM + (or FTM) as the proportion of the number of persons who are carriers of a sign, in the total number of surveys.
Calculate the genetic structure of the population (the frequency of allelic genes and possible genotypes), using the Hardivainberg formula: P² + 2pq + q² \u003d 1, wherep² - the frequency of homozygotes on the dominant allele (genotype TT), 2pq - frequency of heterozygot (TT), Q²
- The frequency of homozygotes on a recessive allele (TT) in the studied population. When calculating the frequencies of the dominant (T) and recessive allele (T), the P + Q \u003d 1 should be used in the population (T).
Test tasks
* Test tasks with multiple answers
1. Chemical compounds, inducing mutations: 1) Metagnes; 2) methylene; 3) Mutagena.
2. * The main mechanisms of the mutation process are violations of the following matrix processes: 1) broadcast; 2) replication; 3) transcription; 4) Reparations.
3. Unnecessary change is called: 1) Reversion; 2) isolation; 3) Modification.
4. * High variability of quantitative signs due to: 1) polygenic nature of inheritance; 2) the influence of environmental factors; 3) genotypic heterogeneity; 4) homozigotization during the selection process.
5. * Revealed genetic activity of the following genetic factors: 1) electricity; 2) X-ray radiation; 3) gamma radiation; 4) ultraviolet radiation; 5) Extreme temperatures.
6. It is inherited from parents to descendants: 1) a sign; 2) modification; 3) the reaction rate; 4) phenotype; 5) Modification variability.
7. The form of variability, as a result of which the left-hand-eyed child was born in the right--eyed parents: 1) mutational; 2) combinative; 3) modifications; 4) Random phenotypic.
8. The form of variability, as a result of which, with an animal on the occurrence of the animal, there was a change in coloring and nozzles of hair: 1) mutational; 2) combinative; 3) modifications; 4) Random phenotypic.
9. The form of variability, as a result of which in the family of five-pile parents (recessive sign) was born a child with a sense of hand: 1) mutational; 2) combinative; 3) modifications; 4) Random phenotypic.
10. * The reason for increasing the frequency (occurrence) of several pathological alleles in a person population: 1) increasing the level of radiation pollution;
2) immigration from areas with unfavorable ecological situation; 3) raising fertility; 4) an increase in life expectancy; 5) improving the level of medical care.
11. A characteristic feature of modifications, in contrast to mutations: 1) the material for evolution; 2) their formation is accompanied by a change in the genotype; 3) are usually useful; 4) are inherited.
12. In adults of ermine rabbits living in natural conditions, most of the body has white wool, and the tail, ears and face are black, which is due to the difference in body sections on the temperature of the skin - this is a manifestation of the shape of variability: 1) mutational; 2) combinative; 3) modifications; 4) Random phenotypic.
13. The shape of variability, as a result of which, with the onset of puberty, the young man changed the voice of the voice, the mustache and beard appeared: 1) mutational; 2) combinative; 3) modifications; 4) Random phenotypic.
14. Type of typical variation curve: 1) straight line; 2) Coupler curve; 3) exhibitor; 4) Circle.
15. * Resistant increase in the frequency of one of the dominant genes in the population of animals is associated with the followingthe most likely reasons: 1) change in the conditions of existence; 2) raising fertility 3) migration of part of animals;
4) extermination of animals by man; 5) absence natural selection.
Part 4.
Population-species level of organization
Organic evolution is an objective process.
The population is an elementary evolutionary unit. The main characteristics of the population as an ecological-genetic system (population area, the number of individuals in the population, age composition, political composition, the main morpho-physiological characteristics of the population, genetic heterogeneity of the population, the genetic unity of the population). Mutations of different types - elementary evolutionary material. Genetic processes in populations. Elementary evolutionary phenomenon.
Elementary factors of evolution. Mutation process. Population waves. Insulation. Genetic and automatic processes. Natural selection.
The formation of adaptations is the result of natural selection. Classification and mechanism for the occurrence of adaptations. The relative nature of adaptations.
The form is the main stage of the evolutionary process. The concept, criteria and structure of the species. The speciation is the result of microevolution. Main paths and ways
speciation.
The patterns of macroevolution. The evolution of ontogenesis (integrity and stability, embryonization and autonomization of ontogenesis, ontogenesis is the basis of philogenesis). The evolution of phylogenetic groups (philogenesis forms, the main directions of evolution, the extinction of groups and its causes). Evolution of organs and functions. Evolutionary progress.
The origin and evolution of man.
4.1. Organic Evolution - Objective Process
Control tasks
1. One of the evidence of evolution is the unity of the organic world, in which there are a number of organisms that occupy an intermediate position between major systematic groups,- Transitional forms. On the image
4.1 some of the currently existing transitional forms of organisms are presented. Get acquainted with these organisms and indicate in their structure the signs of different types of organization.
2. The skeleton of the extremities of amphibians, reptiles, birds and mammals, despite the rather large differences in the appearance of the limbs and the function they perform, it turns out to be constructed similarly (Fig. 4.2). What does the resemblance to the structure of the limbs carrying very different functions, vertebrates?
Fig. 4.1. Now existing transition forms:
1 - a sword, occupying an intermediate position between modern typical arthropod and fossil trilobites; 2 -peripatus, carrying signs of arthropods and ring worms; 3 Evglen connecting signs of animals and plants; four - lictery of Szrechovost.similar to the larva of trilobitis; five
- crawling Grebnevik connects on a par with signs of intestinal animals signs of flat worms
3. In the structure of almost any organism, it is possible to find organs or structures, relatively underdeveloped and lost their former importance in the process of phylogenesis, are rudimentary organs. Figure 4.3 shows the rudimentary back limbs of Python, barely noticeable rudiments of the wings in Kiwi, rudiments of pelvic bones of cetaceans. What do these authorities indicate?
Fig. 4.2. Gomology of the front limbs of vertebrates
(Salamander, sea turtle, crocodile, bird, bat, whale, mole, man) homologous parts are marked with the same letters and numbers
4. Among the animals of one of the most striking relic forms is Gatteria - the only representative of a whole reptile subclass (Fig. 4.4). It reflects the features of the reptiles living on Earth in the Mesozoic.
Another famous relic - a cilancepie for a latimarium fish, preserved a little changed from Devon.
5. In favor of the existence of kinship of systematic groups of animals, fossil transitional forms are served. Fill in Table 4.1, specifying some signs of the first in comparison with reptiles and real birds.
Fig. 4.3. Examples of rudimentary organs (A - top limbs of python;
B - kiwi wing; V- Elements of the pelvic belt of smooth whale)
List the transitional forms known to you. Why are intermediate forms do not give sufficient evolution evidence?
7. Embeds of birds in the early stages embryonic development It is isolated as a final product of nitrogenous exchange of ammonia, in later urea, and at the last stages of development - urinary acid. Similarly, the headastrics frogs are the end product of the exchange is ammonia, and in adult amphibians
Tail verteons
The ability to fly
Lifestyle
Reproduction
8. The study of the embryonic development of the higher, terrestrial vertebrates showed that they are laid and reach a known level of development. Some bodies that do not have any meaning in an adult animal, but quite similar to the organs characterizing adult fish. Consider Figure 4.6 and answer
about what does the fact of bookmarking the parts of the gill apparatus in the embryos of terrestrial vertebrates?
9. How can I prove the objectivity of the process of the evolution of life on earth?
Fig. 4.5. Fingerprints of the bones of the skeleton and feathers of Archeopteryix
10. Before you is a horse, a mouse, a turtle, butterfly, pine. What methods are the most reliably to establish the relationship of these forms?
The experiments of Mendel have already shown that in relation to the body should distinguish between internal, genetic, factors and external signs. Conceptually this distinction was issued in 1911 by the Danish scientist Wilhelm Johansen, who proposed the concepts of genotype and phenotype. The meaning of this distinction was to establish a determination dependence: genotype -GT; phenotype. The genotype does not include all organism genes, but only those of them that have external manifestations in the form of signs of the body purchased by it in the process of their ontogenesis. Having this in mind, it is said that the genotype includes only genes included in chromosomes.
Demarcation of genotype -GT; The phenotype is of great importance for understanding biological processesbecause it allows you to express
being if not all, then a significant part of those determining processes that take place in the world of biological phenomena. It is clear that they should not be ignored by scientists. But, of course, it does not do without difficulties.
One of them is that the influence of the "third player" should be taken into account, namely the external environment. Moreover, it can be considered two: first, as a physico-chemical factor; Secondly, as a "raising" factor forcing the body to learn something, for example, the ability to avoid danger threatening him. In this section, we will look at the external environment as a physicochemical factor. In this regard, such a question arises: how is the external environment turn on into the determination process, on the side of the genotype or a phenotype?
In search of an answer to this question, it is necessary to take into account that all phenotypic signs are a way to exist protein bodies synthesized in the process of previously considered gene mechanisms. Therefore, the effect of the outer medium on the phenotype is defined as its interaction with some proteins. Two different situations are possible here. First, the transformation of proteins caused by an external environment may remain without any consequences for the body's genotype. This is the case if there is no feedback between proteins and genes focused in chromosomes. But proteins can serve as a plus or, on the contrary, minus-modifiers of gene expressivity. In this case, the effect of the medium that started as a transformation of the phenotype reaches the genotype.
The effect of the medium on the genotype to one degree or another always transforms it. Some of these transformations remain without any consequences for the phenotype, because the gene mechanism with a certain stability is not violated. If transformations are essential, for example, in the case of mutations, they will certainly lead to a significant change in the phenotype.
Thus, the influence of the medium on the phenotype and the genotype in the meaning is divided into two stages. As a physicochemical factor, the medium does not have biological specificity. It does not have this specificity at the "entrance" in the phenotype and genotype. Its influence in a certain way is separated by both the genotype and the phenotype. And only as a result of such separation, a dynamic factor arises, truly transforming relevant biological specificity.
So, the influence of the medium, expressed in the transformation of the genotype and the phenotype, does not determine the specifics of biological processes.
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It would remain the meaning of it with the same even if the external environment would be completely absent as a physicochemical factor. Sometimes, trying to express the connection of the genotype with a phenotype, convert the genotype -GT scheme; Phenotype Kommersant genotype -GT; External environment - "phenotype. But in this case, the nature of the external environment is interpreted in the same vein as the biological specificity of the genotype and phenotype. And this is an error, because, as noted, the medium does not have biological specificity as a physicochemical factor.
We now turn to the genes included in the genotype. Interestingly, they largely regulate themselves. This circumstance indicates, in particular, the role played by enhancers, transposons and methylated DNA. Enhancers (from English, Enhance - enhance) are regulatory DNA sequences, which activate the transcription, being from the promoter at a distance of several thousand nucleotide par1. Transposons - DNA fragments that can be separated and implemented into it, accelerating the evolution of the genotype. The share of transposons accounts for about 10% of the Genomic DNA of the highest eukaryot. DNA methylation is translated into cytosine in 5-methylcitosin. It happens enzymatic way. About 5% of cytosins translates into DNA of mammals in the process of dNA replication in 5-methylcitosin. It is firmly established that the methylation of DNA regulates the activity of genes. Thus, the genotype itself contains a number of factors that determine its differential expression.
Great importance The mechanism of expression of the genotype also has the interaction of genes with each other, in particular dominant and recessive genes. According to the law of dominance of Mendel, the first generation of hybrids is uniformly, because they only show the expression of dominant alleles. Expression of recessive alleles is suppressed.
Another type of gene expression is that their interaction leads to the formation of the same feature. In this case, much depends on the co-relative force of the expressivity of genes. It is known, for example, that the color of the hairproof mammals is determined by three genes. One gene is responsible for the distribution of color pigment on the hairproof, the second determines the color of the hair, black or brown, the third gene produces enzymes,
those. The substances of protein nature, from which it depends, whether hair will be painted in a small color. If the third gass is passive, then the hair color will be white.
Proteins regulators also have relevant importance in gene expression. Driving on DNA, they either activate or suppress the expression of the genotype. different types cells multicellular organism They have different proteins-regulators, as a result, in each type of cells there is its own set of genes. And it happens that one protein controller controls several genes. On the other hand, individual genes are managed by a combination of proteins.
Thus, the process of determination by the genotype of the phenotype is due to many dynamic factors. Genes affect themselves, experiencing the protein component of the phenotype, as well as physicochemical factors of the medium, such as radioactive emissions and temperature. It is extremely significant that transcription is always directed towards proteins, and not from them. Proteins affect DNA of O RNA, but do not transcribe them. This circumstance can be expressed using the terms of the genotype and the phenotype. The phenotype affects the valve, but does not determine its biological specificity. Not any influence is directly biological.
The complex nature of the biological determination of the genotype - "! The phenotype puts the researcher before a difficult task. The fact is that he is not able to trace all the nuances of this process. Therefore, he does not have anything else, how to emulate essential and insignificant features of the genotype and phenotype. Biological research should always be selective. However, there is no "nothing surprising. Nature is also selective. In the desire to "know her intricacies have to be a selective and biologist. In this regard, they are not just about genotype and phenotype, but about partial ("truncated") genotype and phenotype. The concept of genotype is the concretization of the concept of genome. The concept of partial genotype is a concretization of the concept of genotype.
1. What is the role of the genotype and environmental conditions in the formation of a phenotype? Give examples.
Some signs are formed only under the influence of the genotype and their manifestation does not depend on the conditions of the medium in which the body develops. For example, an IV group of blood is formed in the genotype of the genes I A and I B in the genotype of genes I A and I B, regardless of the living conditions. At the same time, growth, body weight, the number of erythrocytes in the blood and many other signs depend not only on the genotype, but also on environmental conditions. Therefore, organisms having identical genotypes (for example, monosigital twins) may differ from each other through the phenotype.
In 1895, the French nerd Bonier held the following experience: divided the young dandelion plant into two parts and began to grow them in different conditions - on the plain and high in the mountains. The first plant has reached a normal height, and the second turned out to be dwarf. This experience shows that the formation of a phenotype (i.e. signs) affects not only genotype, but also environmental conditions.
Another example illustrating the influence of the external environment on the manifestation of signs is to change the wool color from the Himalayan rabbits. Usually at 20 ° C wool they have white on all body, with the exception of black ears, paws, tail and face. At 30 ° C, rabbits grow completely white. If the Himalayan rabbit has a shaper on her side or back and contain it at air temperature below 2 ° C, then instead of white wool grows black.
2. What is a modification variability? Give examples.
Modification variability is a change in the phenotype under the action of environmental factors occurring without changing the genotype within the reaction rate.
For example, at dandelion, the length of the leaves and their form differ significantly even within the same plant. It is observed than at a lower temperature, the formation of leaves was, the smallest and the larger cutouts have a sheet plate. On the contrary, at a higher temperature, larger leaves are formed with small cutting plates.
In an adult, depending on the nutrition and lifestyle, the mass of the body changes, the cows can change the villas, in the chickens - egg production. In a person who produced high in the mountains, over time, the content of blood erythrocytes increases in order to ensure body cells with oxygen.
3. What is the reaction rate? Prove on specific examples, the validity of the statement that the sign is not inherited, but its reaction rate.
The reaction rate is the limits of the modification variability of the trait. Some signs, such as the length of the leaves, the height of the plants, the mass of the animal body, the walledness of cattle, egg production chickens, have a wide reaction rate. Other, such as the size of flowers and their shape, coloring of seeds, flowers and fruits, suit animals, fatness of milk - a narrower norm of reaction.
The reaction rate is determined by the genotype and is transmitted by inheritance. For example, the more time a person spends under direct sunlight, the more melanin is synthesized in open areas Skin and, respectively, her darker color. As is known, the intensity of the tan is not transferred by inheritance, but is determined by the specific living conditions of a person. In addition, even at a constantly staying under the direct sunlight of a person of the EuropeanID race, the skin cannot synthesize the number of melanin, which is characteristic, for example, for representatives of the Negroid race. This example suggests that the variability range (reaction rate) is predetermined by the genotype and is not inherited actually a sign, and the body's ability under the action of environmental conditions to form a certain phenotype.
4. Describe the basic properties of modifications. Why is an unetebled variability also called group? Defined?
Modifications have the following main properties:
● Relief - with the change of external conditions in individuals changes the degree of severity of certain signs.
● In most cases, they are adequate, i.e. The severity of the sign is directly dependent on the intensity and duration of the action of a factor.
● Have an adaptive (adaptive) character. This means that in response to the changed conditions of the environment among individuals, such phenotypic changes are manifested that contribute to its survival.
● Massibility - the same factor causes approximately the same changes in individuals similar genotypically.
● Modifications are not inherited, because Modification variability is not accompanied by a change in the genotype.
An uneteblel (modification) variability is called group, since certain changes in the conditions of the medium cause similar changes in all individuals of a particular type (the properties of mass). Modification variability is also called defined, because Modifications are adequate in nature, are predictable and accompanied by a change in the phenotype of individuals in a certain direction.
5. What statistical methods are used to analyze the variability of quantitative signs?
To characterize the degree of variability of quantitative features, such statistical methods are most often used as the construction of a variational series and a variation curve.
For example, the number of spikelets in the complex seams of wheat of one variety varies in fairly wide limits. If you place an ears to increase the number of spikes, then the variation range of the variability of this feature consisting of a separate version. Meeting frequency of individual options in variational row Nonodynakova: Most often there are ears with an average number of spikes and less often - with more and smaller.
Distribution option in this row can be depicted graphically. To do this, on the abscissa axis, the values \u200b\u200b(V) are deposited in the order of their increase, on the ordinate axis - the frequency of occurrence of each option (P). The graphic expression of the variability of the feature, reflecting both the variation and frequency of the occurrence of the individual variant, is called a variation curve.
6. How important is in practice to know the rate of the reaction of signs in plants, animals and man?
Knowledge of the patterns of modification variability and the reaction rate is of great practical importance, as it allows you to foresee and plan to plan many indicators in advance. In particular, the creation of optimal conditions for the implementation of the genotype makes it possible to achieve high productivity of animals and plant yields. Knowledge of the norm of the reaction of various signs of a person is necessary in medicine (it is important to know how certain physiological indicators correspond to the norm), pedagogy (upbringing and learning, taking into account the abilities and capabilities of the child), easy industry (sizes of clothing, shoes) and many other areas of human activity .
7 *. If primulus, which in normal conditions has red flowers, transfer to a greenhouse with a temperature of 30-35ºС and high humidity, new flowers on this plants will be already white. If this plant is returned to the conditions of relatively low temperature (15-20ºC), it again begins to bloom with red flowers. How can this be explained?
This is a typical example of modification variability. Most likely, the increase in temperature causes a decrease in the activity of enzymes, providing the synthesis of red pigment in the petals, up to their complete inactivation (at 30-35 ° C).
eight*. Why, on the poultry farms, the luminous day of the nuclei chuckles are artificially prolong up to 20 hours, and the bed-broilers are reduced to 6 hours per day?
The length of the daylight is an important factor affecting the sexual behavior of birds. An increase in the duration of the light day activates the production of genital hormones - thus nuclear hens stimulate on an increase in egg production. A short daylight causes a decrease in sexual activity, so broilers' roosters move less, they do not fight with each other, and all the resources of the body are directed to an increase in body weight.
* Tasks marked with stars, suggest the nomination by students of various hypotheses. Therefore, when setting a mark, the teacher should be guided not only for the answer given here, but to take into account each hypothesis, assessing the biological thinking of students, the logic of their reasoning, the originality of ideas, etc. After that, it is advisable to acquaint students with the answer given.
