Heredity is the property of all living organisms to transmit their characteristics and properties from generation to generation.
The patterns by which traits are passed on from generation to generation were first discovered by the great Czech scientist Gregor Mendel (1822-1884)
Monohybrid crossing is the crossing of forms that differ from each other in one pair of studied alternative traits, for which alleles of one gene are responsible.
Monogenic inheritance, studied during monohybrid crossing, is the inheritance of a trait for the manifestation of which one gene is responsible, the various forms of which are called alleles. For example, in a monohybrid cross between two pure lines of plants that are homozygous for the respective traits - one with yellow seeds (dominant trait) and the other with green seeds (recessive trait), we can expect that the first generation will have only yellow seeds, because the allele yellow seeds is dominant over the green allele.
When monohybrid crossing, Mendel's first law (law of uniformity) is observed, according to which when homozygous organisms are crossed, their F1 descendants exhibit only one alternative trait (dominant), and the second is in a latent (recessive) state. F1 offspring are uniform in phenotype and genotype. According to Mendel's second law (the law of segregation), when heterozygotes are crossed, their F2 offspring exhibit segregation according to the genotype in a ratio of 1:2:1 and according to the phenotype in a ratio of 3:1.
Analyzing crossing is the crossing of a hybrid individual with an individual homozygous for recessive alleles, that is, an “analyzer”. The meaning of an analyzing cross is that the descendants of an analyzing cross necessarily carry one recessive allele from the “analyzer”, against which the alleles obtained from the analyzed organism should appear. For analytical crossbreeding (excluding cases of interaction of genes), it is characteristic that the splitting by phenotype coincides with the splitting by genotype among the descendants. Thus, analyzing crossbreeding makes it possible to determine the genotype and the ratio of gametes of different types formed by the analyzed individual.
Mendel, conducting experiments on the analytical crossing of pea plants with white flowers (aa) and purple heterozygotes (Aa), obtained a result of 81 to 85, which is almost equal to the ratio of 1: 1. He determined that as a result of crossing and the formation of a heterozygote, the alleles do not mix with each other and subsequently appear in their “pure form”. Subsequently, Bateson, on this basis, formulated the rule of gamete purity.
Dihybrid crossing (Mendel's 3rd law):
Dihybrid is the crossing of parental pairs that differ from each other in alternative versions of two traits (two pairs of alleles). For example, Mendel crossed pure pea plants for two traits (digomozygous) with dominant (yellow color and smooth seed surface) and recessive (green color and wrinkled seed surface) traits: AA BB x aa bb.
When crossing Fl hybrids (AaBb x AaBb) with each other, Mendel obtained 4 phenotypic classes of hybrid F2 pea seeds in the quantitative ratio: 9 yellow smooth: 3 yellow wrinkled: 3 green smooth: 1 green wrinkled. However, for each pair of characters (9 glands + 3 glands: 3 greens + 1 green; 9 glands + 3 glands: 3 wrinkles + 1 wrinkles), the splitting in F2 is the same as in a monohybrid cross, i.e. 3: 1. Consequently, inheritance for each pair of characteristics occurs independently of each other.
In dihybrid crossing of pure pea plants (AABB x aabb), F1 hybrids were phenotypically and genotypically uniform (AaBb) in accordance with Mendel’s first law. By crossing diheterozygous pea individuals with each other, a second generation of hybrids was obtained, having four phenotypic combinations of two pairs of characters (2 2). This is explained by the fact that during meiosis in hybrid organisms, from each pair of homologous chromosomes in anaphase 1, one chromosome moves to the poles. Due to the random divergence of the paternal and maternal chromosomes, gene A can end up in the same gamete with gene B or gene B. A similar thing will happen with gene a. Therefore, hybrids form four types of gametes: AB, Ab, aB, ab. The formation of each of them is equally probable. The free combination of such gametes leads to the formation of four variants of phenotypes in the ratio 9: 3: : 3: 1 and 9 classes of genotypes.
Both in mono- and dihybrid crossings, the F1 offspring are uniform in both phenotype and genotype (manifestation of Mendel’s first law). In the F2 generation, splitting occurs for each pair of traits according to phenotype in a ratio of 3: 1 (Mendel’s second law). This indicates the universality of Mendel's laws of inheritance for traits if their defining genes are located in different pairs of homologous chromosomes and are inherited independently of each other. 5. What will be the segregation by genotype and phenotype in F2 if the hybrids of the second generation of dihybrid crosses (see Punnett grid) reproduce by self-pollination? According to the phenotype, the split will be 9: 3: 3: 1, and according to the genotype there will be 9 classes of genotypes. 6. What number of gamete types are formed by individuals with genotypes AaBbCcDd and aaBbDdKkPp? The number of gamete types (N) of heterozygous organisms is determined by the formula: N = 2 n, where n is the number of heterozygotes. In our case, the two indicated genotypes are heterozygous for four traits, so n is equal to 4, i.e., they form 16 types of gametes each.
1. Fruits, their classification, methods of distribution in nature.
Classification of fruits.
1. The mother is a carrier of the color blindness gene, the father sees colors normally. As a symptom, color blindness can be inherited by their children.
Ticket number 21
1. Types of relationships between organisms in populations.
A species is a collection of individuals that are similar to each other and interbreed. It breaks up into smaller natural groups of individuals - populations inhabiting separate, relatively small areas of the range of a given species.
A population is a group of single-species organisms occupying a certain area of territory within the species’ range, freely interbreeding and partially or completely isolated from other populations,
The existence of species in the form of populations is a consequence of the heterogeneity of external conditions.
Interrelations of organisms in populations.
The organisms that make up a population are related to each other through various relationships.
They compete with each other for certain types of resources, they can eat each other or, on the contrary, together defend themselves from a predator. Internal relationships in populations are very complex and contradictory. The reactions of individuals to changes in living conditions and population reactions often do not coincide. The death of individual weakened organisms (for example, from predators) can improve the qualitative composition of the population (including the quality of the hereditary material available to the population), and increase its ability to survive in changing environmental conditions.
Existence in the form of populations increases the internal diversity of a species, its resistance to local changes in living conditions, and allows it to gain a foothold in new conditions. The direction and speed of evolutionary changes occurring within a species largely depend on the properties of populations.
The processes of formation of new species originate in changes in properties
2.Characteristics of angiosperms. Classification of angiosperms.
3.Look at mollusk shells and find similarities and differences in shell structure.
In Bivalves: For example, Toothless has 1) a shell 2) siphons 3) a leg 4) a mantle 5) gills 6) a place of attachment of the adductor muscle. In bivalve mollusks, the shell consists of two valves connected on the dorsal side by an elastic ligament. There are closing muscles that close the shell. Similarities with Cephalopods:
Around the mouth there are tentacles, or arms, which are seated with several rows of strong suckers and have powerful muscles. The tentacles of cephalopods, like the funnel, are homologues of part of the leg. In embryonic development, the tentacles are laid on the ventral side behind the mouth from the leg bud, but then move forward and surround the mouth opening. The tentacles and funnel are innervated by the pedal ganglion. There is also a shell.
organisms among themselves and with inanimate surrounding nature 4. Science that studies the structure and functions of whole cells and their individual components 5. A special way of existence of protein bodies 6. The lowest level of organization of living matter 7. The highest level of organization of living matter 8. Level of organization of living matter , on which bacteria, amoebas, ciliates and other protozoa exist 9. The level of organization of living matter, uniting populations of different types of living organisms (for example, green plants, hares and foxes) 10. The level of organization studied in the course of human anatomy 11. The level of organization, including individuals of only one species) for example, prides of lions) 12. The ability to maintain the constancy of the internal environment, independent of changes in natural factors 13. General property of living systems, combining the processes of digestion, respiration and excretion in humans and animals 14. General property of living systems ensuring continuity of life 15. General property of living systems, expressed in changes in the shape, structure and size of the body
1.Science that studies patternsinheritance of traits
2.The science that studies chemical
organization of living
3.The lowest level of organization of living matter
4.Ability
maintain a constant internal environment, regardless
From
changes in natural factors
5. General property of living systems that combines processes
digestion, respiration and excretion in humans and animals
1. Science that studies patterns of inheritance of traits
2. Genetic patterns were first formulated
3. Paired chromosomes, each of which is received by the body from one of the parents
4. Chromosomes containing a set of identical genes
5. Chromosomes located in the same organism, but different in size, shape and set of genes
6. Genes located in the same regions of homologous chromosomes, responsible for the synthesis of the same proteins, but having different nucleotide sequences
7. What will the names of genes encoding the same protein (for example, hemoglobin or melanin) but containing different amino acid sequences be called?
8. In a monohybrid cross, the characteristics are examined
9. Based on the color gene (in Mendel’s experiments), the number of traits was found in peas
10. Zygote that received two different alleles
11. Zygote that received both identical alleles
12. Gene denoted by a lowercase letter when crossed
13. What is the name of the allele denoted by a capital (capital) letter when crossed?
14. Allele that manifests itself phenotypically only in the homozygous state
15. An allele that manifests itself externally in any case, if it is present at all in the genotype of an individual
16. Zygote genotype, designated AA
17. Zygote genotype, designated Aa
18. Zygote genotype, designated aa
19. The set of external signs of an organism
20. The totality of all hereditary characteristics of an organism
21. The totality of all genes of a species or population
22. The splitting of hybrids in the second generation follows the formula 3:1
23. Genotype of parental forms of peas (“pure lines”) in Mendel’s experiments
24. Genotype of descendants (first generation hybrids) in peas in Mendel’s experiments
25. First generation pea color
26. Mendel obtained F1 by pollination
27. Mendel obtained F2 by pollination
28. Type of segregation when crossing a heterozygote and a homozygote for a recessive
29. A monoheterozygote produces... varieties of gametes
30. In hybrids, with monohybrid crossing and complete dominance, ... phenotypic classes are formed
31. Mendel's laws concerned this type of inheritance
32. Non-allelic genes located on the same chromosome, if crossing over does not occur, are inherited
33. Author of the chromosomal theory of heredity
34. Chromosomes that differ in size and shape in men and women
35. Chromosomes that do not differ in size and shape
36. Sex-linked genes are located
37. Hemophilia and color blindness in humans and inheritance of coat color in cats are examples
38. The genes for these traits are located
39. Male mammals and fruit flies are heterozygous for sex-linked traits
40. Random changes in the genetic material of an individual
41. Change in the number of chromosomes
42. Change of one or more nucleotides
43. Change in the amino acid sequence of proteins
44. Author of the law of homological series of hereditary variability
45. The main method of genetics, not applicable in human genetics
46. A method of human genetics based on staining chromosomes and subsequent study of their size and shape
47. A method of human genetics based on analysis of pedigrees and tracking the transmission of a certain trait
48. Method of human genetics, based on the analysis of phenotypic manifestations of traits in identical twins
49. A method of human genetics based on the analysis of the enzymatic activity of proteins that catalyze important physiological processes
50. Substances that cause mutations
Option 1
1. What science studies the patterns of heredity and variability of organisms?
1) anatomy 2) genetics 3) physiology 4) cytology
2. What science studies the causative agents of influenza and AIDS?
3. What is the name of the method based on studying the course of development of the object under study?
3) historical method 4) experimental method
4. Which doctor should you contact first if you have problems with your hearing?
1) nutritionist 2) otolaryngologist 3) ophthalmologist 4) endocrinologist
5. The subject of what science is the organism shown in the picture?
6. Who was the first to discover cells in a section of cork and first use the term “cell”?
Appearances
clear image of the object in question
Answer:
8. To what level of organization of living matter does a chromosome belong?
1) cellular 2) molecular 3) organ-tissue 4) subcellular
9. What is the name of the method that allows you to study natural phenomena under given conditions?
1) observation method 2) description method 3) comparative method 4) experimental method
10. The ability of living organisms to respond to certain external influences with specific reactions
called...
1) adaptation 2) variability 3) irritability 4) self-regulation
11. To what level of organization of living matter does the chloroplast belong?
1) molecular 2) subcellular 3) cellular 4) organ-tissue
12. What characteristic (property) of living organisms refers to their ability to maintain the constancy of their
chemical composition and intensity of metabolic processes?
1) constant chemical composition 2) metabolism and energy dependence
3) self-regulation 4) self-reproduction
13. Identify the nature and type of inheritance of traits from generation to generation based on the study of the pedigree
human beings are enabled by… the method of genetics.
1) biochemical 2) twin 3) genealogical 4) hybridological
14. The origin and evolution of man is studied ...
1) anatomy 2) anthropology 3) paleontology 4) taxonomy
15. A sign of living things, the essence of which is the ability of living systems to maintain relative
the constancy of one’s internal environment is...
1) adaptation 2) homeostasis 3) discreteness 4) heredity
Option 2
1. What science studies birds?
1) histology 2) zoology 3) ornithology 4) entomology
2. What science studies the causative agents of tetanus and tuberculosis?
1) bacteriology 2) botany 3) virology 4) mycology
3. What is the name of the method based on the analysis of the similarities and differences of the objects being studied?
1) method of observation and description 2) comparative method
3) experimental method 4) modeling method
4. What science is used to study the organisms shown in the picture?
5. The optical system of the microscope is represented by...
1) eyepiece and lens 2) lens and stage
3) glass slide and concave mirror 4) flat mirror and eyepiece
6. Who discovered single-celled organisms?
1) Robert Hooke 2) Anthony van Leeuwenhoek 3) M. Schleiden and T. Schwann 4) R. Virchow
7. Establish the sequence of actions when examining finished microslides under a microscope.
Write down the corresponding sequence of numbers in your answer.
2) secure the finished microslide with clamps on the stage
3) consider the microslide as a whole
4) looking through the eyepiece, raise or lower the tube (spotting scope) until
5) place the finished microslide on the stage
6) consider the details of the object being studied
Answer:
8. The science of the historical development of living nature is called...
1) biology of individual development 2) history of biology
3) paleontology 4) evolutionary theory
9. The science of tissues of living organisms is called...
1) cytology 2) histology 3) embryology 4) materials science
10. At what level of organization of living matter do the processes of protein biosynthesis occur?
1) molecular 2) cellular 3) organismal 4) biogeocenotic
11. “The cells of all organisms are similar in chemical composition, structure and functions” - these are the provisions of the theory...
1) cellular 2) ontogenesis 3) chromosomal 4) evolution
12. At what level of organization of living matter does the interaction of different types of living things take place?
organisms?
1) organismal 2) population-species 3) biogeocenotic 4) biosphere
13. What is the ability of living organisms to reproduce their own kind called?
1) homeostasis 2) reproduction 3) heredity 4) ontogeny
14. What method is used to study the structure of a cell?
1) biochemical 2) microscopy 3) observation 4) cytogenetic
15. At what level of organization does metabolism and energy conversion occur?
Ponomareva N.A. MBOU "Lyceum No. 56" Rostov-on-Don
Option 3
1.What scientific method does the picture illustrate?
2. What science deals with the development of new and improvement of existing plant varieties, animal breeds and
strains of microorganisms?
1) biology 2) biotechnology 3) botany 4) selection
3. What biological method is used to determine the vital capacity of a person’s lungs?
1) measurement 2) modeling 3) observation 4) experiment
4. Which scientist created the doctrine of the types of higher nervous activity and signaling systems?
1) Vavilov N.I. 2) Vernadsky V.I. 3) Pavlov I.P. 4) Timiryazev K.A.
5. Which medical specialist should you contact if you have skin lesions or a rash?
1) dermatologist 2) otolaryngologist 3) therapist 4) endocrinologist
6. Cell theory is based...
1) Robert Hooke 2) Anthony van Leeuwenhoek 3) M. Schleiden and T. Schwann 4) R. Virchow
7. Establish the sequence of actions when examining finished microslides under a microscope.
Write down the corresponding sequence of numbers in your answer.
2) secure the finished microslide with clamps on the stage
3) consider the microslide as a whole
4) looking through the eyepiece, raise or lower the tube (spotting scope) until
appearance of a clear image of the object in question
5) place the finished microslide on the stage
6) consider the details of the object being studied
Answer:
8. Anthropology is the science that studies...
1) patterns of geographical distribution of living organisms
2) historical and evolutionary process of formation of a person’s physical type
3) the origin of human races
4) the origin and evolution of humans as a biosocial species
9. At what level of organization does the “recording” of hereditary information take place?
10. What is the ability of organisms to maintain a relatively constant physical and chemical composition called?
1) homeostasis 2) osmosis 3) metabolism 4) nutrition
11. Which scientist formulated a natural scientific theory of the origin of life on Earth?
1) Lunin N.I. 2) Oparin A.I. 3) Pirogov N.I. 4) Severtsov A.N.
12. Biotechnology is...
1) the science of breeding new varieties or breeds of animals
2) the science of simple animals
3) science about the development of life at present
4) a set of industrial methods that allow the use of living organisms to produce valuable
for human products
13. What science studies communities of organisms in their interaction with inanimate nature?
1) biotechnology 2) bioinformatics 3) bioengineering 4) biocenology
14. At what level of organization of living things do transcription and translation occur?
1) genetic 2) molecular 3) organ 4) organismal
15. One of the most important principles of organization of biological systems is their...
1) homeostasis 2) openness 3) reproduction 4) self-regulation
Ponomareva N.A. MBOU "Lyceum No. 56" Rostov-on-Don
10 -11 grade General biology. Introduction (§ 1-4)Option 4
1.An example of which scientific method illustrates the plot of the picture?
2. What science studies the organisms shown in the picture?
3. Using what method was it possible to establish the patterns of inheritance of hemophilia in humans?
1) twin 2) biochemical 3) hybridological 4) genealogical
4. Which scientist discovered the law of independent inheritance of traits?
1) Crick F. 2) Mendel G. 3) Morgan T. 4) Ultson D.
5. Which specialist should you contact if the number of red blood cells and hemoglobin decreases?
in blood?
1) dermatologist 2) therapist 3) surgeon 4) endocrinologist
6. The theory of the origin of life on Earth is based...
1) Robert Hooke 2) Anthony van Leeuwenhoek 3) A.I. Oparin 4) R. Virchow
7. Establish the sequence of actions when examining finished microslides under a microscope.
Write down the corresponding sequence of numbers in your answer.
2) secure the finished microslide with clamps on the stage
3) consider the microslide as a whole
4) looking through the eyepiece, raise or lower the tube (spotting scope) until
appearance of a clear image of the object in question
5) place the finished microslide on the stage
6) consider the details of the object being studied
Answer:
8. The inheritance of hemophilia in humans was established using ... method.
1) twin 2) genealogical 3) hybridological 4) microbiological
9. At what level of organization of living organisms does the transfer of hereditary information and
transformation of matter and energy?
1) molecular 2) cellular 3) organ 4) organismal
10. What is the ability of organisms to acquire new characteristics and properties during life called?
1) homeostasis 2) variability 3) metabolism 4) heredity
11. Which scientist discovered the process of double fertilization in flowering plants?
1) Kovalevsky V.O. 2) Lunin N.I. 3) Mechnikov I.I. 4) Navashin S.G.
12. Scientific research consists of several stages. At the stage after collecting facts...
1) a hypothesis is put forward 2) a theory is built 3) an experiment is carried out 4) a problem is formulated
13. Which of the indicated levels of organization of living nature is the smallest?
1) biocenotic 2) population-species 3) cellular 4) organismal
14. In taxonomy they use the method...
1) classification 2) modeling 3) generalization 4) comparison
15. What method is used to study the structure of plastids?
Ponomareva N.A. MBOU "Lyceum No. 56" Rostov-on-Don
10 – 11 grade General biology. Introduction (§ 1-4)Option 5
1.What scientific method does the figure illustrate?
2. What science studies the biological objects shown in the picture?
3. Which method allows you to study the number and structure of chromosomes?
1) genealogical 2) hybridological 3) biochemical 4) cytogenetic
4. Which scientist discovered the blood circulation?
1) Harvey U. 2) Mechnikov I.I. 3) Pasteur L. 4) Pavlov I.P.
5. Which specialist doctor should you contact if there is a persistent increase in blood pressure and
increase in heart rate?
1) dermatologist 2) otolaryngologist 3) therapist 4) endocrinologist
6. The founder of the law of germinal similarity...
1) Ch. Darwin 2) G. Mendel 3) K. Baer 4) N.I. Vavilov
7. Establish the sequence of actions when examining finished microslides under a microscope.
Write down the corresponding sequence of numbers in your answer.
2) secure the finished microslide with clamps on the stage
3) consider the microslide as a whole
4) looking through the eyepiece, raise or lower the tube (spotting scope) until
appearance of a clear image of the object in question
5) place the finished microslide on the stage
6) consider the details of the object being studied
Answer:
8. Phenology is a science that studies...
1) algae 2) classification of living organisms based on their relationship
3) seasonal changes in wildlife 4) humans
9. At what level of organization does the circulation of substances and the transformation of energy associated with
vital activity of all living organisms?
1) molecular 2) cellular 3) biosphere 4) organismal
10. What is the name given to the ability of organisms to respond to certain environmental influences?
or some other active reaction that allows them to survive?
1) homeostasis 2) irritability 3) metabolism 4) nutrition
11. Which scientist discovered the blood circulation?
1) Pasteur L. 2) Haeckel E. 3) Harvey W. 4) Brown R.
12. To obtain high-yielding plants, breeding uses...
1) hybridological method 2) polyploidy method 3) methodical selection 4) mass selection
13. Which of the biological methods is the twin method - the study of the manifestation of signs in
identical twins?
1) description 2) comparison 3) experiment 4) modeling
14. A sign of living things, the essence of which is the ability of organisms to reproduce their own kind, is...
1) discreteness 2) irritability 3) reproduction 4) growth
15. What method is used to study the structure of the nucleus?
1) biochemical 2) light microscopy 3) cytogenetic 4) electron microscopy
Ponomareva N.A. MBOU "Lyceum No. 56" Rostov-on-Don
Ponomareva N.A. MBOU "Lyceum No. 56" Rostov-on-Don
10-11 grade General biology. Introduction (§ 1-4)
ANSWERS
| Option 1 | Option 2 | Option 3 | Option 4 | Option 5 |
| 1-2 | 1-3 | 1-2 | 1-2 | 1-4 |
| 2-3 | 2-1 | 2-4 | 2-1 | 2-3 |
| 3-3 | 3-2 | 3-1 | 3-4 | 3-4 |
| 4-2 | 4-1 | 4-3 | 4-2 | 4-1 |
| 5-4 | 5-1 | 5-1 | 5-2 | 5-3 |
| 6-1 | 6-2 | 6-3 | 6-3 | 6-3 |
| 7-521436 | 7-521436 | 7-521436 | 7-521436 | 7-521436 |
| 8-4 | 8-4 | 8-4 | 8-2 | 8-3 |
| 9-4 | 9-2 | 9-1 | 9-2 | 9-3 |
| 10-3 | 10-1 | 10-1 | 10-2 | 10-2 |
| 11-2 | 11-1 | 11-2 | 11-4 | 11-3 |
| 12-3 | 12-3 | 12-4 | 12-4 | 12-2 |
| 13-3 | 13-2 | 13-4 | 13-3 | 13-2 |
| 14-2 | 14-2 | 14-2 | 14-1 | 14-3 |
| 15-2 | 15-2 | 15-2 | 15-4 | 15-4 |
Genetics - the science of the laws of heredity and variability.
Heredity - This is the property of living organisms to transmit from generation to generation similar signs and characteristics of individual development.
The process of transmitting hereditary information over a number of generations is called inheritance. Inheritance is based on the ability of DNA to replicate.
Variability- this is a property of living organisms, the opposite of heredity, which consists in the ability of daughter organisms to acquire characteristics and properties that their parents did not have.
The units of heredity and variability are genes. Gene - this is a section of a DNA molecule that encodes the primary structure of a protein (polypeptide), tRNA or rRNA.
Stages of genetic development:
1) the study of heredity at the organismal level (G. Mendel - discovery of the laws of inheritance, development of the hybridological method; E. Chermak, K. Correns, G. de Vries - rediscovery of Mendel's laws).
2) the study of heredity at the cellular level (T. Morgan - development of the chromosomal theory of heredity).
3) study of heredity at the molecular level (F. Crick and J. Watson - model of DNA structure; development of molecular biology and genetic engineering).
The general tasks of genetics include the study of:
Methods of storing and transmitting genetic information in different organisms;
Material carriers and mechanisms for the implementation of genetic information;
Patterns of variability and the role of variability in the evolutionary process;
Methods of reparation (restoration) of genetic material.
Genetics is a complex science. It includes: genetics of humans, plants, animals, fungi, microorganisms; molecular genetics; population genetics; medical genetics, etc. Each of these sciences solves its own particular problems. For example: the tasks of medical genetics will be the diagnosis, treatment and prevention of hereditary human diseases. To solve these problems, various research methods are used.
Hybridological method developed by Mendel. It involves hybridization of organisms that differ in one or more characteristics, followed by analysis of the resulting offspring. Allows you to install patterns of inheritance of individual characteristics. Basic principles of the method:
a) inheritance is studied according to individual alternative characteristics;
b) accurate quantitative accounting and analysis of the inheritance of each trait is carried out over several generations.
Genealogical method. The method is based on the compilation and analysis of pedigrees. Allows you to install:
a) whether this characteristic is inherited or not;
b) type of inheritance (sex-linked or autosomal, dominant or recessive);
c) the probability of manifestation of the trait in subsequent generations.
a) Autosomal dominant type of inheritance.
b) X-linked dominant type of inheritance.
d) X-linked recessive type of inheritance.
e) Autosomal recessive type of inheritance.
Thanks to the genealogical method, it has been proven that many diseases are inherited. For example, it has been established that the genes for hemophilia (blood clotting) and color blindness (color blindness) are located on the X chromosome.
Cytogenetic method - This is a method for studying the karyotype of organisms microscopically. Allows:
a) study the karyotype;
b) identify chromosomal and genomic mutations.
This method made it possible to establish that the karyotype of a normal person includes 46 chromosomes. In hereditary diseases caused by genomic mutations (Down syndrome, Shereshevsky-Turner syndrome), the number of chromosomes changes; and in diseases caused by chromosomal mutations (cry-of-the-cat syndrome), the structure of chromosomes changes. The material for cytogenetic research is peripheral blood cells (lymphocytes).
Dermatoglyphics method based on the study of patterns of fingers, palms and feet. Finger patterns are strictly individual (with the exception of identical twins) and remain unchanged until the end of life. This allows the use of dermatoglyphic analysis data in medical genetics, forensic medicine and criminology. Sections of dermatoglyphics:
a) fingerprinting (study of patterns on fingertips);
b) palmoscopy (study of the palms);
c) plantoscopy (examination of feet).
In genetics, this method is used to determine the zygosity of twins and diagnose some hereditary diseases.
Twin method is based on the study of the manifestation of traits in identical (develop from one fertilized egg and have the same genotypes) and fraternal (develop from two fertilized eggs and have different genotypes) twins. Allows you to install the role of genotype and environmental factors in the formation of phenotype.
Biochemical methods are based on the study of enzyme activity and the chemical composition of cells, which makes it possible to identify diseases caused by gene mutations, which are based on metabolic disorders (albinism, phenylketonuria, sickle cell anemia, etc.). Using these methods you can identify:
a) gene mutations;
b) establish heterozygous carriers of recessive genes.
Population-statistical method makes it possible, using the Hardy-Weinberg law, to calculate the frequency of occurrence of normal and pathological genes and genotypes in a population.
Prenatal diagnostic methods. They include studies that can detect the disease before the birth of the child (ultrasound, choriopexy - obtaining and examining a piece of chorion, amniocentesis - obtaining and examining amniotic fluid).
Simulation method. It is based on Vavilov’s law of homologous series in hereditary variability. Allows the study of human diseases in animals that may suffer from these diseases. For example, hemophilia can be studied in dogs; diabetes mellitus - in rats.
Basic concepts of genetics: allelic genes, dominance and recessivity, homozygote and heterozygote, genotype and phenotype.
Genotype - the totality of all genes of an organism (the totality of all hereditary information).
Phenotype - the totality of all external and internal characteristics of an organism. The phenotype develops as a result of the interaction of the genotype with environmental factors. Therefore, even organisms that have the same genotype may differ from each other phenotypically depending on the conditions of their development and existence. A phenotype is a special case of the implementation of a genotype under specific environmental conditions.
A gene is a hereditary factor responsible for the formation of a trait. Each gene exists in several alternative forms. These forms are called allelic genes or alleles. Allele - one of several alternative forms of a gene. The gene can be represented by two (alleles for yellow and green color of pea seeds) or more alleles (gene I, which determines the formation of blood groups according to the AB0 system, is represented by three alleles: I A; I B; I 0).
Allelic genes - these are genes that are located in identical loci of homologous chromosomes and determine the development of alternative traits. Alternative (mutually exclusive) characteristics - for example, yellow and green color, smooth and wrinkled shape of pea seeds. Homologous chromosomes are chromosomes of one pair, identical in size, shape, and gene composition, but different in origin: one from the mother, the other from the father. Allelic genes are designated by the same letters of the Latin alphabet.
If identical alleles are found in identical loci (sections) of homologous chromosomes (for example: A and A, a and a), then such an organism is called homozygous. This organism produces one type of gamete.
And if homologous chromosomes contain different alleles (A and a), then such an organism is called heterozygous. It produces two types of gametes.
The trait and its corresponding gene, which appears in first generation hybrids, is called dominant, and which does not appear - recessive.
Dominant gene - suppresses the manifestation of other alleles and appears in a hetero- and homozygous state; it is denoted by a capital letter of the Latin alphabet (A).
Recessive gene - appears only in the homozygous state; it is denoted by a lowercase letter of the Latin alphabet (a).
Genetic experiments of G. Mendel on inheritance in monohybrid crossing. Patterns of inheritance in monohybrid crossings: the law of uniformity of first-generation hybrids and the law of segregation.
The patterns of inheritance of traits were discovered by the Czech scientist Gregor Mendel. To do this, he used the hybridological method.
Organisms differ from each other in many ways. If, during crossing, the parent forms are analyzed according to one pair of alternative characteristics, then such a crossing is called monohybrid. A cross that takes into account two pairs of alternative traits is called dihybrid; if there are many traits, it is called polyhybrid.
Before conducting experiments, Mendel obtained pure lines of peas (homozygous organisms) through self-pollination. In experiments when crossing pea varieties that had yellow and green seeds, all the offspring (first generation hybrids) ended up with yellow seeds. The discovered pattern was called Mendel's first law, or the law uniformity of first generation hybrids.
The allele for the yellow color of pea seeds (A) completely suppresses the allele for the green color (a) and dominates, so all descendants are the same. When recording crosses, the resulting gametes are taken in a circle.
yellow green cytological bases
P 1: ♀ AA ´ ♂ aa P 1: ♀ A † † A ´ ♂ a † † a
F 2: AA Aa Aa aa F 2: A † † A A † † a A † † a a † † a
Mendel's second law (law of segregation): when crossing hybrids of the first generation with each other, the offspring exhibit split by phenotype 3:1 (3 parts yellow and 1 part green), and by genotype 1:2:1.
To explain the 1st and 2nd laws, Bateson proposed the rule of gamete purity, according to which each gamete contains one of a pair of allelic genes, i.e. gametes are “pure” in terms of allelic genes. Allelic genes in a heterozygous state do not change each other and do not merge.
Cytologically, the gamete purity hypothesis and Mendel's first two laws are explained by the divergence of homologous chromosomes to the cell poles in anaphase 1 of meiosis, as a result of which each gamete receives one of a pair of homologous chromosomes, which carries only one of a pair of allelic genes.
When studying biological patterns, researchers deal not with individual single events, but with their totality. Each event is subject to various environmental influences. However, all events taken together reveal certain statistical patterns that are established when studying a large number of objects.
Thus: the split observed in second-generation hybrids is statistical in nature. Therefore, in the offspring of hybrids with a small number of descendants, the actual split obtained during crossing may not correspond to the expected one (3: 1), but with an increase in the number
descendants, the probability of the expected ratio increases.
Sign- any feature of an organism, any quality or property by which one can be distinguished from another.
Alternative signs- mutually exclusive variants of the same trait (example: yellow and green color of pea seeds).
Domination- the predominance of the trait of one of its parents in a hybrid.
Dominant trait- the predominant trait that appears in the first generation of offspring in heterozygous individuals and dominant homozygotes (see below).
Recessive trait- a trait that is inherited, but is suppressed and does not appear in heterozygous descendants; manifests itself in the homozygous state of a recessive gene.
Phenotype- the totality of all external and internal signs of the body. The phenotype is formed through the interaction of the genotype with the organism’s environment.
Allelic, dominant and recessive genes. Genotype
Allele- one of the alternative forms of existence of a gene that determines a certain trait. The number of alleles of the same gene can reach several dozen.
■ Each chromosome or chromatid can carry only one allele of a given gene.
■ Only two alleles of each gene are present in the cells of one individual.
Locus- the region of the chromosome on which the gene is located.
Allelic genes- genes located in the same loci of homologous chromosomes and responsible for alternative manifestations of the same trait (example: genes responsible for human eye color). Allelic genes are designated by the same letters of the Latin alphabet: A, a; B, b.
Non-allelic genes- genes located on non-homologous chromosomes or at different loci of homologous chromosomes.
Dominant genes- genes corresponding to dominant traits; are designated by capital Latin letters (A, B).
Recessive genes- genes corresponding to recessive traits; are indicated by lowercase Latin letters ( a, b).
Genotype- the totality of all the genes of a given organism.
Crossbreeding
Crossbreeding- producing offspring by artificially combining the genetic material of different parents (different cells) in one cell.
Genetic record of the cross:
■ First line: letter R(parents), genotype of the female body, crossing sign x, genotype of the male body; under the designations of genotypes, the characteristics of organisms can be indicated;
■ second line: letter G(gametes) and (under genotype designations, in circles) gametes of female and male individuals;
■ third line: letter F k (descendants), genotypes of descendants (characteristics of organisms can be indicated under the designations of genotypes); k - generation number.
Homozygote- zygote containing the same alleles of one gene are dominant ( AA, dominant homozygote) or recessive ( aa, recessive homozygote).
■ A homozygous individual produces one type of gamete and does not split when crossed.
Heterozygote - zygote, containing two different alleles of the same gene ( Ahh).
■ A heterozygous individual in its offspring produces segregation for this trait. Produces several types of gametes.
Rule (hypothesis) of gamete purity. Since each chromosome or chromatid can carry only one allele of a given gene, when chromosomes (during the first division of meiosis) or chromatids (during the second division of meiosis) diverge, only one of the alleles of each allelic pair leaves with them into the haploid cells of the gametes.
That's why: any gamete of an organism carries only one allele of each gene, i.e. Alleles in gametes do not mix.
Consequences of the rule of gamete purity:
■ homozygous the body produces only one type of gamete:
an organism heterozygous for one pair of genes forms two types of gametes (of the two homologous chromosomes of the zygote in the process of meiosis, one chromosome is with the gene A- gets into one gamete, the other - with the gene A- into another gamete): 
Hybridization- the process of crossing two organisms of the same species (intraspecific hybridization) or different species or genera (distant hybridization).
Hybrid- an organism obtained by crossing genetically different organisms.
Monohybrid cross- crossing of organisms that differ from each other by alternative variants of only one trait (one pair of alleles).
Analysis cross- crossing the organism under study with an organism that has a recessive homozygous genotype (and produces only one type of gametes with recessive alleles). Allows you to determine the genotype of the organism being studied. Used in plant and animal breeding.
Dihybrid cross- crossing of organisms that differ from each other in alternative versions of two traits (two pairs of alleles).
Polyhybrid crossing- crossing of organisms that differ from each other in alternative versions of three or more characteristics.
Chained inheritance- joint inheritance of genes localized on the same chromosome; genes form linkage groups.
Feature splitting- a certain ratio manifested among the offspring of the second and subsequent generations between the numbers of individuals characterized by alternative characteristics of the original parental forms.
■ Specific quantitative relationships between the numbers of individuals carrying the characteristics of each of the parental forms are determined by whether the parent organisms are homozygous or heterozygous for these characteristics.
Mendel's first law
Mendel's first law (law of uniformity of first generation hybrids, or rule of dominance ) describes the crossing of homozygous individuals: n When crossing homozygous individuals (taken from pure lines of the same species) that differ in one of a pair of alternative characters, the resulting first-generation hybrids are uniform in both phenotype and genotype.
Consequence: if the first generation is uniform in one of the alternative traits of the parent individuals, then this trait is dominant , and the parent individuals homozygous according to alternative characteristics.
Mendel's second law
Mendel's second law(law of segregation) describes a mono-hybrid crossing of heterozygous individuals: when hybrids of the first generation (i.e., heterozygous individuals) differing in one of a pair of alternative characteristics are crossed with each other, in the second generation a split is observed in a ratio of 3: 1 in phenotype and 1 : 2:1 by genotype. 
Phenotypic breakdown: three parts of second generation descendants with dominant sign and one part - with recessive .
Genotype breakdown: one part of the descendants are dominant homozygotes (AA), two parts of the descendants are heterozygotes (Ah) and one part is recessive homozygotes (aa).
Corollaries of Mendel's second law:
■ if the offspring of parental individuals gives a phenotypic split close to 3: 1, then the original parental individuals for these alleles heterozygous ;
■ test cross: if the offspring of the parents gives a phenotypic split close to 1: 1, then one of the parents was heterozygous, and the other was homozygous and carried a pair of recessive alleles.
Mendel's third law
Mendel's third law (law of independent inheritance of traits ) describes a dihybrid crossing of individuals: When crossing homozygous organisms that differ in two or more pairs of traits, in the second generation independent inheritance of the genes of different allelic pairs and their corresponding traits is observed.
Those. each pair of allelic genes (and their corresponding alternative traits) is inherited independently of each other ( another formulation of Mendel's 3rd law ).
❖ Determination of possible genotypes and the probabilities of their occurrence in individuals of the second generation: first, the genotype of the first generation and the type of its gametes Gf1 are determined (see table),
after which the genotypes of individuals and the probabilities of their occurrence are determined using Punnett gratings .
Punnett grid- a table with the help of which the splitting of independently inherited traits is depicted and analyzed. Female gametes are written horizontally in the top row of this grid, male gametes are written vertically in the left column, and the genotypes of daughter individuals are recorded at the intersections of rows and columns.
Example: crossing homozygous pea individual characterized by two dominant signs - yellow color and smooth shape of seeds - with homozygous individual pea having two alternative recessive characteristic - green color and wrinkled shape of the seeds.
Since, according to Mendel's third law, splitting for each characteristic occurs independently: by color (in the second generation) in a ratio of 3: 1 (see Mendel’s second law), by shape - also in a ratio of 3: 1, then splitting according to phenotype, i.e. by combination of characteristics, is observed in the ratio (3: 1) 2 = 9: 3: 3: 1 (nine parts out of 16 are yellow smooth seeds, three parts are yellow wrinkled, another three parts are green smooth and one part are green wrinkled seeds ).
From the data of the Punnett lattice it follows that during dihybrid crossing of homozygous individuals (in particular, peas) in individuals of the second generation, nine different genotypes (genotypic classes), which fall into four phenotypic classes. Descendants dominant in two traits (yellow smooth pea seeds) have one of the following genotypes (the probability of occurrence of a given genotype is indicated in parentheses): AABB (1/16), AAVv (2/16), AaBB(2/16) or AaVv(4/16); dominant according to the first and recessive according to the second characteristic (yellow wrinkled seeds) - AAbb(1/16) or Aaww(2/16); recessive according to the first and dominant according to the second characteristic (green smooth seeds) - aaBB(1/16) or aaVv(2/16); recessive for both characteristics - genotype aabv (1/16) (green wrinkled seeds).
❖ Segregation by genotype is as follows:
■ when dihybrid
crossing: (1:2:1) 2;
■ when polyhybrid crossing (1:2:1) n, where n is the number of segregating pairs of alleles.
❖ Phenotype splitting looks like:
■ when dihybrid
crossing: (3: 1) 2 = 9: 3: 1;
■ when polyhybrid
crossing (3: 1) n.
Corollaries of Mendel's third law:
■ if the analysis of segregation for two traits gives a phenotypic ratio close to 9: 3: 3: 1, then the original parental individuals are diheterozygous for these traits;
■ in general, each new gene doubles the number of types of different gametes and triples the number of genotypes. Consequently, an individual heterozygous for n pairs of genes can produce 2" types of gametes and 3" different genotypes;
■ the number of different classes of phenotypes is equal to the number of different types of gametes in the presence of dominance and the number of different genotypes in the absence of dominance.
Notes:
■ Mendel's third law, i.e. independent combination of characteristics is carried out only on the condition that the allelic genes that determine these characteristics are located in different pairs of homologous chromosomes;
■ it does not explain the patterns of inheritance of genes located together on the same chromosome;
❖ Calculation of the frequency of a specific genotype in the offspring of parents differing in a certain number of independently inherited genes:
■ First, the probability of occurrence of the corresponding genotype is calculated separately for each pair of genes;
■ the desired frequency is equal to the product of these probabilities. Example: calculate the frequency of the genotype Aabbcc in the offspring of the cross AaBbcc x AaBbCc. The probability of the appearance of the Aa genotype in the offspring from the crossing Aa x Aa is 1/2; the probability of the appearance of the bb genotype in the offspring of the crossing Bb x Bb is 1/4; the probability of the appearance of the Cc genotype in the offspring of a Cc x CC cross is 1/2. Therefore, the probability of occurrence of the AabbCC genotype is (1/2) x (1/4) x (1/2) = 1/16.
Conditions for fulfillment and meaning of Mendel's laws
Mendel's laws are fulfilled only on average, with a large number of experiments of the same type. They are a consequence of the random combination of gametes carrying different genes, and the statistical nature of inheritance, determined by a large number of equally probable encounters of gametes.
❖ Additional terms, under which Mendel's laws are satisfied:
■ one gene must control only one trait, and one trait must be the result of the action of only one gene;
■ dominance must be complete;
■ there must be no linkage between genes;
■ equal probability of formation of gametes and zygotes of different types;
■ equal probability of survival of offspring with different genotypes;
■ statistically large number of crosses.
❖ The meaning of Mendel's laws:
■ these laws are universal in nature and do not depend on the systematic position of the organism and the complexity of its structure;
■ with their help, you can calculate the number of types of gametes formed and establish possible combinations of dominant and recessive traits in hybrids.
