Methods for studying human heredity. Presentation on the topic "methods for studying human genetics" Presentation on biology, methods of genetics

Description of the presentation by individual slides:

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Option 1 1-6 Option 2 1-5 2-8 2-7 3-1 3-4 4-7 4-6 5-4 5-3 6-3 6-10 7-9 7-9 8-5 8 -2 9-10 9-1 10-2 10-8 The presentation begins not with the formulation of the topic, but with the actualization stage. 1. Update. Students are asked to give a definition or supplement the definition with a concept. Answers: Genetics is the science of the laws of heredity and variability. The science of cells is cytology. A section of a DNA molecule that carries information about one polypeptide chain - a gene. A recessive gene is suppressed. Dominant gene - suppressive, predominant. A system of crossing organisms with different characteristics in order to study the nature of inheritance of characteristics in a series of generations - a hybridological method.

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Methods for studying human genetics Goal setting and motivation. The topic is formulated. The goal of the lesson is set

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“Man was and will be the most curious phenomenon for man...” V.G. Belinsky Name of the method Characteristics What it is used for Studying new material, its awareness and comprehension. During the lesson, students are asked to fill out a table.

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1. Genealogical method. The family's pedigree is demonstrated. Question for students: do you know what this is?

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Genealogical method Stages: Collecting information about the family (a pedigree is compiled based on one or more characteristics). Pedigree analysis to determine the nature of inheritance of a trait. Albinism, color blindness, hemophilia, sickle cell anemia. Using the information, students enter data using the genealogical method into a table.

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Using symbolism to compile pedigrees, analyze the inheritance of the trait of color blindness in the proposed scheme, answering the questions: Who introduced the color blindness gene into the family? How is a trait inherited in the second and third generations? Is this trait linked to gender? The task is completed in writing in a notebook, then the correctness of the answers is checked. Symbolism for drawing up genealogies in the appendix to the lesson. Answers: 1) The gene for color blindness was introduced into the family by the grandmother; 2) In the second generation, one woman is a carrier, two men are color blind. In the third, one boy is color blind. 3) The trait is sex-linked. The color blindness gene is localized on the X chromosome.

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Pedigree of the British Royal Household (inheritance of hemophilia) The student's message about the inheritance of hemophilia in the British royal family is illustrated with a pedigree.

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Twin method 2. Twin method. Have you ever watched baby strollers in a big city? You probably paid attention to especially wide ones, simply “doubled”. Two children sat comfortably in it. These are twins. Two girls or two boys are so similar to each other that passersby involuntarily stop and smile. But there are also dissimilar twins in double strollers, including those of different sexes. How to understand such a phenomenon? Photographs appear sequentially on the slide: 1 – twins in a stroller; 2 – identical twins.

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Consider the formation patterns of the two types of twins. Complete the sentences or insert the missing words into the text. Identical twins develop from……. . Fraternal twins develop from ………. Identical twins have a ……… genotype, they are always ………. floor. Fraternal twins have………. genotypes can be either ………… sex or ………….. . How to understand the phenomenon of identical and fraternal twins? Students view information in diagrammatic form. Data is recorded in a notebook using statements from the slide. Gaps (in order): one zygote, different zygotes, identical, one, different, one, different.

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The twin method made it possible to identify the influence of ……… and ……... on the formation of the phenotype. Information about the twin method is extracted from the text and entered into a table. One of the key phrases is missing the words: genotype and environment.

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Cytogenetic method 3. Cytogenetic method. On the slide is a drawing of a child with Down syndrome. An excerpt from the woman’s letter is read: “I was under extreme stress in the maternity hospital. I couldn’t understand why a child with a pathology was born to me?! Like everyone else, I dreamed that my baby would be the smartest, most beautiful, but life had other plans. It takes a lot of strength and love to raise a child with special needs. And the most difficult thing is not to be ashamed of your child.”

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Cytogenetic method Study of the chromosome set (karyotype) of a person. Normally, a human karyotype includes 46 chromosomes - 22 pairs of autosomes and 2 sex chromosomes. The use of this method made it possible to identify a group of diseases associated with either a change in the number of chromosomes or a change in their structure. Using information about the cytogenetic method, students enter data into the table. The overall frequency of births of children with chromosomal diseases is approximately 5 newborns per 1000. In the far right photo below is the procedure for amniocentesis (collection of amniotic fluid from the fetal bladder for cytogenetic research).

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Chromosomal abnormalities Karyotype of a girl with Down syndrome (trisomy 21 pairs of chromosomes) Karyotype of a boy with Klinefelter syndrome (44XXY) Karyotype of a girl with Shereshevsky-Turner syndrome (44X0) Students are given information about some chromosomal abnormalities: Down syndrome, Klinefelter syndrome, Shereshevsky-Turner syndrome .

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Down syndrome is not a death sentence Today it is well known: the diagnosis of Down syndrome is not a death sentence. Children with the syndrome can go to school and kindergarten. In Moscow there is an Art Center and the “Theater of the Innocent”, where adults study. An example of strong will and hard work is Andrey Vostrikov from Voronezh, who in September 2006 represented Russia at the Special Olympics in Turin and became the absolute champion in artistic gymnastics. A famous American artist who was born with Down syndrome is Michael Jurgue Johnson. Photos of A. Vostrikov and M. Johnson appear by clicking during the story. This slide is the result of studying the cytogenetic method.

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Contains phenylalanine. Not recommended for use by patients with phenylketonuria. A bottle of sparkling water is on display. Question for students: - Have you paid attention to the information that is given on the label of a bottle of sparkling water? Find unclear words that may relate to our lesson. - What is phenylketonuria?

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Biochemical method The study of hereditary diseases associated with metabolism. Based on studying the nature of biochemical reactions in the body, metabolism to establish the carriage of an abnormal gene or clarify the diagnosis. The information is being studied. The data is entered into the table. Today in Russia the biochemical method is used very successfully for early diagnosis of diseases such as phenylketonuria, hypothyroidism, galactosemia, adrenogenital syndrome, and cystic fibrosis. On the fifth day, blood is taken from newborns for analysis, which makes it possible to diagnose the disease on time, begin treatment and avoid serious consequences. The photo shows blood sampling from newborns.

Genetics is a science that studies two fundamental properties of living organisms - heredity and variability

Genetics is a weird lady

And let her sometimes insist stubbornly.

That genes are stronger than upbringing,

And that any influence will be interrupted.

Heredity: it's not our fault

What shapes a personality is only that.

development of methods for managing heredity and variability
regulation of the formation of natural and artificial populations
studying the nature of genetic diseases
addressing the persistence of natural and engineered species.

For genetic research, a person is an inconvenient object: a large number of chromosomes impossibility of experimental crossing late onset of puberty small number of descendants in each family

Genealogical method
Biochemical method
Dermatoglyphic method

The genealogical method is the study of a person's ancestry. Its use is possible only when direct relatives are known - ancestors and descendants of the owner of a hereditary trait on the maternal and paternal lines in a number of generations
It is widely used in medical genetics, as it allows one to calculate the probability of the manifestation of any trait in future descendants
Main goals:
Establishing the hereditary nature of the disease
Establishing the type of inheritance of the disease
Use in medical genetic consultations

Genealogical method

Inherited traits and diseases

Eye cataract

Diabetes

Congenital deafness

Albinism

Dwarfism

Ability to roll the tongue into a tube

Freckles

Cleft lip

Polydactyly

Marfan syndrome

The syndrome is caused by a hereditary malformation of connective tissue. Patients often die from aortic aneurysm. The only compensation is an increased level of adrenaline in the blood, so patients are in an excited state all their lives and become incredible workaholics.

World famous personalities suffered from Marfan syndrome: Abraham Lincoln - US President (height 193 cm), Hans Christian Andersen - a great writer, Niccolo Paganini - a great violinist (the disease gave him great technical capabilities).

In the 20th century there lived no less talented “nosies”. This is Charles de Gaulle - President of France and Korney Chukovsky - Soviet children's writer

A number of traits are inherited in a sex-linked manner

Y-linked inheritance

Hypertrichosis (increased hair growth in the auricle0
-webbing between fingers

X-linked inheritance

Hemophilia
-Colorblindness

The use of the genealogical method has shown that with consanguineous marriage, the likelihood of deformities, stillbirths, and early mortality in the offspring increases significantly. A striking example of this is the inheritance of hemophilia in the royal houses of Europe.

Queen Victoria is widely known to be a carrier of the hemophilia gene

Genetics is a stubborn thing. But, nevertheless, general principles always imply exceptions: children from a related marriage can be normal, healthy and even talented C. Darwin A. PUSHKIN A. Lincoln CLEOPATRA A. LINCOLN CLEOPATRA

Among the relatives of the outstanding composer J. S. Bach there were more than 50 musicians, 20 of whom are deservedly considered famous.
The Mozart family is rich in musical talents, Bernoulli,
literary - Dumas.

Twins are children born at the same time. They are identical (monozygotic) and fraternal (dizygotic). Monozygotic twins develop from one zygote, which at the cleavage stage is divided into two or more parts. Therefore, they are genetically identical and always of the same sex. They are characterized by a high degree of similarity in many ways. Observation of such twins provides material about the role of heredity and environmental factors in the development of traits.

Concordance (degree of similarity) of certain human characteristics

Signs

Monozygotic

Blood type

twins

Dizygotic

Eye color

twins

Hair color

Papillary lines

Bronchial asthma

Tuberculosis

Schizophrenia

European women 1 for every 69 births

Black American women 1 in every 60 births

Japanese women 1 in every 150 births

Chinese women 1 in every 250 births

Nigerians 1 in every 22 births

Based on the study of the human chromosome set. In 1956, Swedish scientists D. Tiyo and A. Levin developed a method for culturing human leukocytes and stopping their division at the metaphase stage using colchicine. This made it possible to study the human karyotype as accurately as possible. Normally, a human karyotype includes 46 chromosomes - 22 pairs of autosomes and two sex chromosomes. The use of this method made it possible to identify a group of diseases associated with either a change in the number of chromosomes or a change in their structure. Such diseases are called chromosomal.

Chromosome diseases include: Klinefelter syndrome, Shershevsky-Turner syndrome, trisonomy X, Down syndrome and others. Most often they are the result of mutations that occurred in the germ cells of one of the parents during meiosis.

Klinefelter syndrome (47,XXY) – always men, characterized by underdevelopment of the gonads, high growth. transverse palmar fold, in adults there is obesity and a tendency to alcoholism, a slight decrease in mental development.

Shershevsky-Turner syndrome (45, x0) - women, short stature, broad shoulders, short lower limbs, short neck, with skin folds, Mongoloid eye shape, infertility.

Down syndrome is one of the most common chromosomal diseases. It develops as a result of trisonomy on chromosome 21.

Patau syndrome - trisomy on chromosome 13, characterized by idiocy, often polydactyly, structural abnormalities of the genital organs, deafness; almost all patients do not live to see one year;

Biochemical method- allows you to detect metabolic disorders caused by gene mutations and, as a consequence, changes in the activity of various enzymes (diabetes mellitus, metabolic disorders of amino acids, lipids, minerals)

Phenylketonuria is a disease of amino acid metabolism. Described in 1934 by A. Fehling.

Clinical signs: increased excitability and muscle tone, tremor, epileptiform seizures, “mouse” odor, mental retardation, decreased melanin formation. Early prevention and treatment – artificial diet.

Children with PKU are born completely healthy. Therefore, if the disease is identified during the first days of life and a diet is followed, it is possible to prevent the destruction of the child’s brain. At the same time, no signs of the disease appear. The baby develops and grows, just like his peers.

A group of metabolic diseases of connective tissue associated with metabolic disorders
Clinical signs: stunted growth, deformation of the spine and sternum, deformation of the knee joints, short neck and hypertrophy of the lower part of the face, large belly. Death is most often from cardiac pathology before age 20.

Dermatoglyphic method

is the study of the papillary patterns of the fingers, palms and feet. These areas of the skin have large dermal papillae, and the epidermis covering them forms ridges and furrows. Dermatoglyphic patterns have a high degree of individuality and remain unchanged throughout life. Therefore, they are used to determine the zygosity of twins, to identify individuals in forensic science, and to establish paternity in forensic medicine. Difficulties of use More than 100 hereditary diseases can be identified along the lines of the hands. (for example, intrauterine exposure to the rubella virus produces abnormalities in patterns similar to Down's disease).

Down's disease: patient's face and palm (b)

Fill in the missing words

The genealogical method - the study of human pedigrees - allows us to establish patterns of inheritance of many traits and hereditary diseases.

The genealogical method establishes patterns of transmission from generation to generation of genes for hemophilia, color blindness, sickle cell anemia, etc.

The twin method - the study of identical twins developed from the same egg - makes it possible to establish which traits depend more on the genotype, and which on the environment and lifestyle.

The cause of Down's disease is the presence of one extra chromosome, the 21st chromosome, in the chromosome set

The biochemical method makes it possible to detect the causes of many diseases associated with hereditary metabolic disorders, the absence or excess of certain elements, enzymes, and hormones in the body.

Cytogenetic method, i.e. microscopic examination of chromosomes in human cells allows us to establish the connection of hereditary diseases with changes in genes, chromosomes or their number.

writing rules:
1.In the first line, the topic is named in one word (usually a noun). 2. The second line is a description of the topic in two words (two adjectives). 3. The third line is a description of the action within this topic in three words. 4. The fourth line is a four-word phrase that shows the attitude towards the topic. 5. The last line is a one-word synonym that repeats the essence of the topic.

Mokhova Elena Viktorovna

teacher of biology and geography

Kirov regional state educational autonomous institution "Vyatka Technical Lyceum"

Lesson summary. Topic: “Methods for studying human genetics.”

Grade 10

“Man was and will be the most curious phenomenon

for a person..."

V.G. Belinsky.

Didactic: purpose : create conditions for awareness and comprehension of a block of new educational information.

Lesson Content Objectives :

A: To create conditions for the formation of ideas about methods for studying human genetics, the inheritance of normal and pathological traits, the influence of heredity and environment on the development of traits.

R: Create conditions for the formation of information competence of students through independent work with sources of information; continue to develop the skills to compare, analyze, and draw conclusions.

Q: Continue the formation of a natural scientific worldview, promote a responsible attitude towards health, a tolerant attitude towards people with hereditary diseases.

Lesson type : a lesson in learning new material.

Forms of organization of cognitive activity: frontal, individual.

Methods : explanatory-illustrative, partially search, problematic.

Means of education : textbook “General Biology” grades 10-11, V.I. Sivoglazov; didactic handouts; presentation “Methods for studying human genetics.”

During the classes :

Organizing time .

I check the class's readiness for the lesson. Greetings students.

Updating. .

Goal setting and motivation

Slide number 2.

Students are asked to define or add a term to the definition. - ………

Genetics

Cell Science - ......

A section of a DNA molecule that carries information about one polypeptide chain - …….. - ………

Recessive gene - ……..

Dominant gene

A system of crossing organisms with different characteristics in order to study the nature of inheritance of characteristics in a series of generations - ………

Students are asked the question:

Is it possible to use the hybridological method to study human genetics?

Students express different opinions, ultimately coming to the conclusion that:

1) experimental crossing of people is impossible;

2) a person has a slow change of generations, a small number of descendants;

3) a large number of chromosomes and linkage groups.

What will we study today? Formulate the topic of the lesson and determine its purpose.

Slide number 3 - topic of the lesson, epigraph.

What questions do you have? Write your question in your notebook. Try to answer it during the lesson. .

Studying new material, its awareness and comprehension .

Slide number 4

Students are asked to fill out the table during the lesson.	Method name	Characteristics of the method

What is it used for?

One day, a young man appeared on the doorstep of the famous geneticist Nikolai Pavlovich Bochkov. It was anxiety that brought him. The fact is that at the age of 3.5 years his first child died. He was born on time, of normal weight, and developed well. And suddenly, from 5-6 months, the baby seemed to be replaced. Having barely learned to smile, he “forgot” how to do it. It became difficult for him to hold his head up. And after 2 months, doctors stated: Tay-Sachs disease. At 3.5 years old the child died.

Nature is capable of reproducing this disaster many times over. And only because once upon a time, in some long-ago generations of the pedigrees of both spouses, the program of this disease was inscribed into the molecular apparatus of heredity. For the time being, it was inactive, passing through one, second, third generations, and suddenly, due to the meeting of spouses with the same genes and the child inheriting this program from its parents, it received an order to turn on.

But the father who lost his son wanted to know something else: would the same fate await his subsequent children? Can he and his wife count on the joys of motherhood and fatherhood? Will fate give them a lucky chance?

Slide number 5.

Students are shown a family pedigree. Question: do you know what it is?

The doctor had to analyze in detail the pedigree of this family along the lines of husband and wife. This is what the genealogical method does.

Slide number 6.

Using the information “Genealogical method”, enter the data into the table.

Slide number 7.

Complete the task: using symbolism to compile pedigrees, analyze the inheritance of the trait of color blindness. Answer the questions:

1) Who introduced the color blindness gene into the family?

2) How is a trait inherited in the second and third generations?

3) Is this trait linked to gender?

Slide number 8.

Report on the inheritance of hemophilia in the Romanov royal family.

2 . Twin method .

Slide number 9.

Have you ever watched baby strollers in a big city? You probably paid attention to the particularly wide ones, simply “doubled”. Two children sat comfortably in it. These are twins. Two girls or two boys are so similar to each other that passersby involuntarily stop and smile. But there are also dissimilar twins in double strollers, including those of different sexes. How to understand such a phenomenon?

Slide number 10.

Complete the task: carefully consider the formation patterns of the two types of twins. Insert the missing words into the text or complete the sentence.

What is it about twins that attract geneticists? (Students work with handouts). Read the text about separated twins, draw a conclusion about the influence of heredity and environment on certain traits.

Slide number 11.

3 . Cytogenetic method.

Slide number 12.

Demonstration of a drawing of a child with Down syndrome.

Excerpt from the letter: “I was under extreme stress in the maternity hospital. I couldn’t understand why a child with a pathology was born to me?! Like everyone else, I dreamed that my baby would be the smartest, most beautiful, but life had other plans. It takes a lot of strength and love to raise a child with special needs. And the hardest thing is not to be ashamed of your child.”

Down syndrome is one of the most famous genetic disorders. According to statistics, one child out of 700-800 newborns is born with this diagnosis. This ratio is the same in different countries, climate zones and social strata. It does not depend on the parents’ lifestyle, their health, the presence or absence of bad habits, nutrition, wealth, education, skin color or nationality.

The cytogenetic method is used to study the causes of such diseases.

Slide number 13.

Carefully study the information “Cytogenetic method”. Enter data into the table.

Most often, chromosomal diseases are the result of mutations that occur in the germ cells of one of the parents during meiosis. These diseases are diagnosed at the intrauterine stage of fetal development. From 12 to 24 weeks, amniocentesis is performed - the collection of amniotic fluid containing exfoliated fetal cells. As a result of the study

the presence of the disease is either confirmed or excluded.

Slide number 14.

Chromosomal abnormalities.

Klinefelter syndrome (47, XXY).

The sick are always men. They are characterized by underdevelopment of the gonads, degeneration of the seminiferous tubules, often mental retardation, and high growth (due to disproportionately long legs).

Down syndrome is one of the most common chromosomal diseases. It develops as a result of trisomy 21 (47). The disease is easily diagnosed because

has a number of characteristic features: shortened limbs, a small skull, a flat, wide nose bridge, narrow palpebral fissures with an oblique cut, the presence of a fold in the upper eyelid, mental retardation. The incidence is 1 in 700-800 newborns.

Slide number 15.

Today it is well known: the diagnosis of “Down syndrome” is not a death sentence. Children with the syndrome can go to school and kindergarten. In Moscow there is an Art Center and the “Theater of the Innocent”, where adults study. An example of strong will and hard work is Andrey Vostrikov from Voronezh, who in September 2006 represented Russia at the Special Olympics in Turin and became the absolute champion in artistic gymnastics. A talented artist, Michael Jurgue Johnson, lives and works in the USA.

Biochemical method.

Slide number 16.

Display of a bottle of sparkling water.

Question for students:

Have you paid attention to the information on the label of a bottle of sparkling water? Find unclear words that may relate to our lesson.

- What is phenylketonuria?

Find information about this disease in the handouts. Read carefully and highlight key words in the text.

Slide number 17.

Carefully read the text “Biochemical method”, enter the data in the table.

The biochemical method makes it possible to identify metabolic disorders in other hereditary diseases.

Slide number 18.

Read the text carefully. What disease are we talking about? Find and correct errors in the text.

The table is closed. Summing up.

Reflection.

Guys, at the beginning of the lesson you wrote down the question to which you were looking for an answer during this lesson. Raise your hand those who answered the question posed./ Some questions and answers are voiced.

What other questions do you have?

The overall result is summed up.

Slide number 19.

The fate of our health is largely determined by genes and chromosomes. And what combinations of genes of each person nature disposes of, that’s what he lives with. Among the variety of genes, there may be those that lead to talent and genius, and those that lead to hereditary diseases. There are many hereditary diseases (4500 forms), most of them are lifelong and severe. But modern scientific achievements, especially the progress of human genetics, make it possible to change the fate of an individual and family. We have the ability to influence our heredity.Each of you must understand that the health of your children and grandchildren depends on a responsible attitude towards your own health.

Slide number 20.

Know the genes of your own family! We have entered the era of family planning, and it will be more successful the more we know about the genetic health of our relatives.

N.P. Bochkov

Homework.

1) Study paragraph 3.17, answer the questions at the end of the paragraph.

2) Answer the question: “What methods or treatments for hereditary diseases do you know? Is it possible to completely cure such diseases?

3) Optional: make a pedigree of your family.

Additional material for students

Genealogical method

Symbolism for drawing up pedigrees:

Twin method

Read the text carefully and draw a conclusion about the influence of heredity and environment on the development of certain traits in twins.

Fate separated them in 1942. As often happened in those difficult times, children lost their parents, wives of their husbands, brothers and sisters.

Twin brothers, like two drops of water similar to each other, by some absurd accident after the death of their parents ended up in different orphanages. Petya was adopted by a childless couple immediately after the war and raised as their own. He received a good education and started a family. All this time I tried to find my brother, but to no avail. Only many years later did Peter learn that Vasily had long been dead. At the age of 22, he went to prison for the second time for theft, where he fell ill with tuberculosis. A few months later, Vasily died without waiting for his release.

The separated twins were never destined to meet.

Biochemical method

Read the text carefully, highlight the key words in it.

Phenylketonuria belongs to a group of diseases associated with metabolism. This blocks the conversion of the essential amino acid phenylalanine to tyrosine, and phenylalanine is converted to pyruvic acid, which is excreted in the urine. The disease leads to the rapid development of dementia in children. Early diagnosis and diet can stop the development of the disease. If a child with phenylketonuria is placed on a very low phenylalanine diet shortly after birth, the symptoms of the disease will be much milder. Since phenylalanine is an essential amino acid, it cannot be completely excluded from the diet. The amount must be sufficient for the child to grow.

Slide 2

Genealogical method

The essence of the genealogical method is the study of pedigrees in those families in which there are hereditary diseases. This method helped to establish the patterns of inheritance of a very large number of very different characteristics in humans, both normal ones, such as eye color, hair color and shape, etc., and those accompanying hereditary diseases.

Slide 3

Legend

Slide 4

Pedigree examples

Slide 5

Alexandra Feodorovna Emperor Nicholas II Tsarevich Alexei Prince Charles Queen of Great Britain Elizabeth II healthy possible carriers of hemophilia healthy Queen Victoria Spanish royal family

Slide 6

Pedigree examples

Slide 7

The genealogical method not only makes it possible to explain the appearance of an undesirable trait, but also serves the purpose of diagnosing the degree of risk in genetic situations

Slide 8

Twin method

Although using the genealogical research method it is possible to find out a lot about the nature of inheritance of various traits in humans, it is impossible to clearly answer the question: is this or that anomaly hereditary or does it represent modification variability due to certain environmental conditions?

Slide 9

Twin method

Twins Non-identical (fraternal) Identical (identical) A B

Slide 10

Similarity between identical and fraternal twins (%)

The twin method makes it possible to find out a person’s hereditary predisposition to a number of diseases.

Slide 11

Cytogenetic method

Based on the study of the human chromosome set.

Normally, a human karyotype includes 46 chromosomes - 22 pairs of autosomes and two sex chromosomes. The use of this method made it possible to identify a group of diseases associated with either changes in the number of chromosomes or changes in their structure. Such diseases are called genomic and chromosomal, respectively. Nondisjunction of sex chromosomes during meiosis, the formation of sperm with an extra sex chromosome and without a sex chromosome.

Slide 12

Most often, chromosomal diseases are the result of mutations that occurred in the germ cells of one of the parents during meiosis

Slide 13

Distribution of children with Down syndrome depending on maternal age.

Slide 14

Examples of genomic mutations

Shereshevsky-Turner syndrome (45, XO) is observed in women. It manifests itself in delayed puberty, underdevelopment of the gonads, absence of menstruation, and infertility. Women with Shereshevsky-Turner syndrome are small in stature, have broad shoulders, a narrow pelvis, shortened lower limbs, and a short, folded neck.

Slide 15

Patients with Klinefelter syndrome (47,XXY) are always male. They are characterized by underdevelopment of the gonads, degeneration of the seminiferous tubules, often mental retardation, and high growth (due to disproportionately long legs).

Slide 16

Population method

This method is based on the tasks of studying the genetic composition of human populations. It allows us to determine the distribution of individual genes in human populations. The population method reveals the proportion of individual variability of people within a particular community (population).

Slide 17

Hardy-Weinberg Law

The frequency of homozygous and heterozygous organisms under conditions of free crossing in the absence of selection pressure and other factors (mutation, migration, genetic drift, etc.) remains constant, i.e. remains in a state of equilibrium.

The Hardy–Weinberg law establishes a mathematical relationship between the frequencies of genes and genotypes. p AA + 2pqAa + q aa = 1 2 2 Frequency of gene A Frequency of gene a

Slide 18

Left-handedness gene frequency by lyceum

Biochemical method

The biochemical method makes it possible to detect metabolic disorders caused by gene mutations and, as a consequence, changes in the activity of various enzymes.

Hereditary metabolic diseases are divided into diseases: carbohydrate metabolism (diabetes mellitus), metabolism of amino acids, lipids, minerals, etc. (albinism, phenylketonuria)

Biochemical method

Slide 20

Phenylketonuria is a disease of amino acid metabolism.

This blocks the conversion of the essential amino acid phenylalanine to tyrosine, and phenylalanine is converted to phenylpyruvic acid, which is excreted in the urine. The disease leads to the rapid development of dementia in children. Early diagnosis and diet can stop the development of the disease. Albinism. Albinos lack the protein + copper tyrosinase enzyme

Slide 21

Methods Human genetics is one of the most rapidly developing branches of science.

It is the theoretical basis of medicine and reveals the biological basis of hereditary diseases. Knowledge of the genetic nature of diseases allows you to make an accurate diagnosis in time and carry out the necessary treatment.

View all slides

study of human heredity

Teacher Smirnova Z. M.

Relevance of the topic

The successful application of medical genetics methods makes it possible to quickly and effectively diagnose various forms of human hereditary pathology.
Methods for studying human heredity
The study of human genetics is associated with difficulties, the reasons for which lie in
impossibility of experimental crossing;
slow change of generations;

a small number of descendants in the family; complex karyotype;

a large number of clutch groups.

Despite all these difficulties, human genetics is successfully developing, thanks to the following

methods

- Genealogical; - Population;

- Cytogenetic; - Twin;

- Biochemical; - Dermatoglyphics.

- DNA diagnostics;

Genealogical or

pedigree method

Proposed at the end of the 19th century by F. Galton.

The method allows us to identify Is this trait hereditary?
(according to its manifestation in relatives);
type of inheritance of the disease (dominant,
recessive, autosomal or sex-linked), homo- and heterozygosity of various family members;

gene penetrance (frequency of its manifestation);

the likelihood of having a child with hereditary

pathology (genetic risk). Stages of the genealogical method

- Collection of data on all relatives of the subject (history): from the proband - the person with whom the study begins families.

2. Constructing a pedigree:

- using standard symbols they do graphic image;

- each generation is numbered with Roman numerals

left.

3. Pedigree analysis and conclusions

Symbols,

used in compiling pedigrees

Classification of types of inheritance of traits in monogenic inheritance

Types of inheritance

autosomal

interlocked with the floor

X-linked

U- linked

dominant

recessive

dominant

recessive

Pedigree analysis

The first task when analyzing a pedigree is to establish hereditary character of the trait.
If the same trait occurs in the pedigree (illness) several times, then you can think about it hereditary nature.
After discovering the hereditary nature of the trait you need to set the inheritance type. For this the principles of genetic analysis are used and various statistical methods for data processing many genealogies.

The main features of the autosomal dominant type of inheritance (A-D type)

Sick in every generation;
A sick child with sick parents;
The manifestation of a symptom (disease) is observed vertically and horizontally;
The probability of inheritance is 100% if one parent is homozygous;
75% if both parents are heterozygous;
50% if one parent is heterozygous.

A A

A A X ahh

A A

A ah ah

A A

1 2 3 4 5 6 7 8

25% healthy

75% sick

50% 50%

sick healthy

1 2 3 4 5 6 7 8 9

The main signs of autosomal recessive inheritance (A-P type)

Not every generation is affected;
A sick child (homozygous) is born to healthy parents (heterozygous);
Men and women are affected equally;
The manifestation of the symptom (disease) is observed horizontally;
Chance of inheritance is 25% (if both parents are heterozygous).

A A X A A

A A A A

F 1

AA A A A A ahh

sick

X-linked dominant mode of inheritance

Patients occur in every generation;
Both men and women are affected, but affected women are 2 times more affected more than men;
Affected women on average pass on the pathological allele

50% sons and 50% daughters;

A sick man passes on the pathological allele to all his daughters and does not pass on to sons, since the latter receive Y from their father

chromosome.

Examples: rickets resistant to vitamin D

Dark tooth enamel

The main features of the X-linked recessive type of inheritance:

Patients do not appear in every generation;
A sick child is born

healthy parents;

They get sick mostly men;
Probability of inheritance:

in 25% of all children, including

in 50% of boys;

This is how people inherit it eka hemophilia, color blindness, etc.

Inheritance of hemophilia in the royal houses of Europe

Queen Victoria

England

Alice

Leopold

Beatrice

Alfonso Maurice XIII

Spain

Victoria-Evgeniya

Alexandra

Nicholas II

Trematan Alfonso

Spain

Waldemar Henry

Prusia

X-linked recessive type of inheritance

X-linked recessive trait in females it appears only when they receive the corresponding allele from both parents ( X h X h ) .

For men – X h Y it develops upon receipt recessive allele from mother.
Mothers pass on the recessive allele to offspring of either sex, and fathers pass it on only to “daughters.”

X h Y

X H X H

X H X h

X H Y

X H X H ; X H Y; X h X H ; X h Y

F 1

Dominant gene (normal)

Recessive gene

X-linked recessive gene

Healthy

Carriers

X h Y

X H Y;

X H Y ;

X h X H ;

X H X H

X H Y;

Main characteristics of Y-linked (holandric) inheritance

Patients in all generations;
Only men get sick;
A sick father has all his sons sick;
The probability of inheritance in boys is 100%.
This is how some forms of ichthyosis are inherited in humans, hairiness of the external auditory canals

(hypertrichosis) some forms of syndactyly,

membrane between toes, etc.

XX x XY Z

Signs of cytoplasmic

(mitochondrial) inheritance

The trait is passed on to offspring only from the mother;

A mother carrying a trait passes it on to all offspring;
The symptom is equally common in both sexes.

Exercise

Define inheritance type

Cytogenetic method

Performed if chromosomal abnormalities are suspected.

The essence of the method

consists of a microscopic study of the karyotype (structural features and number of chromosomes) by recording a karyogram.

Typically, chromosomes in cells are observed during mitosis at the metaphase plate stage.

The object of the study is

bone marrow cells,
peripheral blood lymphocytes,
various embryonic cells.

Indications for cytogenetic examination:

multiple malformations (malformations of the brain brain, musculoskeletal system, heart and genitourinary systems);
mental retardation combined with physical impairment development;
primary infertility in men and women;
recurrent miscarriage, especially in the early stages;
violation of sexual development;
small weight of a baby born at full term pregnancy.

Stages of research

Cultivation of human cells (usually lymphocytes) on artificial nutrient media;

2) Stimulation of mitosis by phytohemagglutinin (PHA);

3) Addition of colchicine (destroys spindle filaments) to stop mitosis at the metaphase stage;

4) treatment of cells with a hypotonic solution, as a result of which the chromosomes “scatter” and lie free;

5) simple and differential staining of chromosomes;

6) studying chromosomes under a microscope and taking photographs;

7) cutting out individual chromosomes and constructing an idiogram.

Centrifuge

Hypotonic solution

Fixation

Red blood cells

Leukocyte department

Coloring

The method allows you to identify genomic and chromosomal mutations

The patient's karyotype is designated as follows:

number of chromosomes,
set of heterochromosomes,
chromosome number,
excess (+) or lack (-) of genetic material.

For example, Down's disease in a boy: 47,XY,21 + ;
cat cry syndrome in a girl: 46,XX,5r-.

Cytogenetic method

Sex chromatin study

The nuclei of all human somatic cells have 23 pairs of chromosomes.

The normal karyotype in women is 46,XX, in men it is 46,XY.

Of these, 22 pairs - autosomes “work” only in pairs.
Sex chromosomes work in the singular.

Of two X chromosomes women one fully

inactivated and is located in the nucleus in the condensed

condition, in the form of lumps (M. Barr and L. Bertram in 1949).

These clumps are called “sex chromatin”, “X-chromatin” or "Barr bodies" - a small formation at the edges of the core.

Normally, in women, 10-30% of cell nuclei have a body Barra,
men are normally absent.

More often For research, a scraping of the epithelium is taken from

the inner surface of the cheek (buccal scraping).

Change in the amount of sex chromatin

indicates a change in the number of sexual chromosomes.

Determination of sex chromatin is used as an express method for prenatal and postnatal sex determination and diagnosis of chromosomal diseases

Indications for sex chromatin testing

presence of clinical signs of Shereshevsky syndrome -

Turner and Klinefelter syndrome;

presence of signs of hermaphroditism;
short stature in girls and women (X-chromatin);
amenorrhea primary and secondary;
high growth in men (Y- and X-chromatin).

Clumps of X-chromatin

among women – norm: 46(XX)

in men – Klinefelter syndrome: 47(XXY)

X-chromatin is absent

in men – norm: 46(XY)

among women – Shereshevsky-Turner syndrome: 45 (XO)

Lumps of X-chromatin (Barr bodies)

in the nuclei of human somatic cells

Normal Male (XY)

or a woman with Shereshevsky-Turner syndrome (TS)

Normal woman (XX)

or a man with Klinefelter syndrome (XXY)

Woman with trisomy X (XXX)

or a man with Klinefelter syndrome (XXXY)

Woman with polysomy X (XXXX)

or a man with Klinefelter syndrome (XXXXY)

FISH – fluorescence hybridization –

a cytogenetic method that is used to determine the position of a specific DNA sequence on metaphase chromosomes or in interphase nuclei in situ.

Denaturation of chromosomal DNA and hybridization with a fluorescent probe.
To determine the regions of chromosomes that have been contacted

fluorescent probes, use fluorescent microscopes.

FISH – fluorescence in situ hybridization

 prepare DNA probes – determined by nucleotide composition

DNA fragments labeled with a fluorescent dye,

 A DNA probe that finds a complementary chromosome in the chromosome being studied

a piece of DNA and attaches to it;

 the site of attachment of the DNA probe is determined by a specific

glow during microscopy of histological preparations,

 the object of microscopy can be metaphase chromosomes and

chromatin of the nuclei of non-dividing cells (interphase chromosomes);

 Using the FISH method, it is possible to determine the localization of genes in

chromosomes and all chromosomal aberrations.

DNA probe

Fluorescent tag

Chromosome region complementary to the probe

FISH studies of interphase and metaphase chromosomes using DNA probes

Biochemical methods

Used for:

- diagnosis of monogenic hereditary diseases with metabolic disorders (enzymopathies);

- diagnosis of heterozygous conditions in adults.

Biochemical methods can identify abnormal enzyme proteins or intermediate metabolic products that indicate the presence of a disease.

Indications for biochemical research:

mental retardation, mental disorders;

impairment of physical development - growth arrest, excessive fat deposition or cachexia;
convulsions, vomiting, increased or decreased tone muscles, jaundice;
intolerance to certain foods and medications, indigestion;
the specific smell of urine and sweat in a child.

Biochemical methods

The objects of biochemical diagnostics are: blood, urine, bone marrow punctures, amniotic fluid liquid, sperm, sweat, feces, etc., in order to determine enzyme activity in biological fluids

Biochemical diagnostics:

primary clarifying

Goal: exclusion of healthy people Goal: clarification individuals from further diagnosis of the disease.

examinations.

Used Used

mass screening selective screening

Mass diagnostics

Mass screening programs are used to diagnose diseases such as

phenylketonuria,
congenital hypothyroidism,
cystic fibrosis,
galactosemia.

For example, to diagnose phenylketonuria, newborn blood is taken 3-5 days after birth. Drops of blood are placed on chromatography or filter paper and sent to the laboratory for determination of phenylalanine.

To determine congenital hypothyroidism, the level of thyroxine in the child’s blood is determined on the 3rd day of life.

Selective diagnostics

Selective diagnostic programs involve checking biochemical metabolic abnormalities in patients with suspected genetic hereditary diseases.

Selective programs usually use more precise methods.

For example, using thin layer chromatography of urine and blood, it is possible to diagnose hereditary disorders of the metabolism of amino acids and mucopolysaccharides.

Using hemoglobin electrophoresis, the entire group of hemoglobinopathies is diagnosed.

Liquid chromatography, mass spectrometry, etc. make it possible to identify any metabolites specific to a particular hereditary disease.

Biochemical methods

in prenatal diagnosis

The biochemical method has found wide application in the prenatal diagnosis of congenital malformations.

Biochemical methods include determining the level of alpha-fetoprotein and human chorionic ganadotropin in the blood serum of a pregnant woman.

These methods are screening methods for identifying congenital malformations.

For example, with neural tube defects

alpha-fetoprotein levels increase.0

Molecular genetic methods –

a large and diverse group of methods designed to detect damage in the structure of a DNA section (gene, chromosome section) right down to decoding the nucleotide sequence.

This is the most accurate method for diagnosing monogenic hereditary diseases.

The methods are based on genetic engineering manipulations of DNA and RNA.
The initial stage of molecular genetic methods is obtaining DNA samples.
The source of genomic DNA is any nucleated cells (leukocytes, chorion, amniotic cells).

DNA diagnostics

Molecular genetic methods (recombinant DNA) - allows you to detect a pathological gene in the genome):

The patient's DNA samples are cut into shorter fragments by restriction enzymes.

The resulting fragments are separated by electrophoresis in a polyacrylamide gel into fractions that differ in size (molecular weight).
Obtaining the required number of copies of certain DNA fractions using polymerase chain reaction (PCR).
Thermal denaturation of the multiplied double-stranded DNA fraction into single-stranded fragments.
Placing these fragments in a medium containing a radioactive probe (single-stranded DNA corresponding to the pathological gene).
If among the DNA fragments there is a pathological sequence complementary to the probe, then double-stranded DNA is formed.
Recording the result using x-ray sensitive film.