Gene mutations. Presentation "Classification of mutations

GBPOU NO "NIZHNY NOVGOROD MEDICAL COLLEGE" Specialty 02/31/03 Laboratory diagnostics

Discipline: “Human genetics with the basics of medical genetics”

Poprukhina Alina Segreevna

Group 321-III Lab

Topic: “Classification of mutations. Chemical mutagens"

Teacher: Vyazhevich L.P.

Goal and objectives

Goal: study the classification of mutations and chemical mutagens

• Study the classification of mutations
• Describe various mutations in the body
• Consider chemical mutagens

Classification of mutations

I. By origin:

1) Spontaneous - occur in nature for no apparent reason. For example, the hemophilia gene can arise spontaneously (no patients were identified during a pedigree study).

2) Induced - occur under the directed influence of mutagenic factors.

Classification of mutations

II. For mutated cells:

1) Generative - mutations that occur in germ cells and are transmitted to descendants during sexual reproduction.

2) Somatic - mutations that occur in somatic cells and are characteristic only of the individual itself.

Breast cancer

Classification of mutations

III. By changing genetic material:

1) Gene mutations are changes within one gene:

a) insertion or deletion of a nucleotide;

b) replacing one nucleotide with another.

Many metabolic diseases are caused by gene mutations, for example: phenylketonuria, galactosemia, cystic fibrosis, etc.

Classification of mutations

2) Chromosomal rearrangements (aberrations) are disturbances in the structure of chromosomes.

a) Intrachromosomal:

• Deletion
• Duplication
• Inversion

b) Interchromosomal:

• Translocation

Classification of mutations

3)Genomic mutations:

a) Polyploidy is a multiple of the haploid increase in the number of chromosomes

b) Heteroploidy is an increase or decrease in the number of chromosomes that is not a multiple of the haploid one.

One extra in a pair is trisomy, one is missing in a pair is monosomy, and both chromosomes are missing in a pair - nullosomy (lethal mutation).

Patau syndrome

Shereshevsky-Turner syndrome

Classification of mutations

IV. By change in phenotype:

1) Amorphous mutations - a mutation has occurred and the trait has disappeared.

2) Hypomorphic - a decrease in the severity of the trait.

3) Hypermorphic - increased severity of the trait.

4) Neomorphic - a feature has appeared that was not there before.

5) Antimorphic - instead of one sign, another has appeared.

Albinism

Anophthalmia

Microphthalmia

Classification of mutations

V. According to the outcome for the body:

1) Lethal - fatal.

2) Semi-lethal – reducing the viability of the organism.

3) Neutral - not affecting viability and life expectancy.

4) Positive - occur rarely, but are of great importance for evolution.

Iris color

Down syndrome

Chemical mutagens

Chemical mutagens are substances of certain types of chemical compounds that, interacting with DNA, affect the genetic apparatus of the cell.

Chemical mutagens

Chemical mutagens include:

• inorganic substances
• simple organic compounds
• complex organic compounds
• alkylating agents
• pesticides
• some nutritional supplements
• petroleum products
• organic solvents
• medicines

Sulfur(II) oxide

Formaldehyde

Signs of chemical mutagens

According to Lobashev, chemical mutagens must have:

• High penetrating ability,
• The ability to change the colloidal state of chromosomes
• A specific effect on changing a gene or chromosome

M. E. Lobashev

Mechanism of action of chemical compounds:

Mutagens enter the cell as foreign substances, after which they begin to react with DNA, changing its structure. Mutations occur during subsequent DNA replications. There are special forms of chemical mutagens that do not change the primary structure of DNA, but form complexes with it. DNA synthesis disorders also occur in these places.

Mechanism of action of mutagens

Nitrous acid causes the amino group to be removed from nitrogenous bases and replaced by another group. This leads to point mutations. Chemically induced mutations are also caused by hydroxylamine.

Nitrates and nitrites in large doses increase the risk of cancer. Some food additives cause arylation reactions of nucleic acids, which leads to disruption of transcription and translation processes.

Nitrous acid

Hydroxylamine

Conclusion

Many very strong chemical mutagens have been discovered, and the mutagenic effect of many chemical compounds that are used in industry and agriculture has been shown. In total, about 3,000 mutagens are now known, most of which are artificially created by people. Many solvents, dyes, disinfectants, substances for extinguishing flames, substances contained in car exhaust gases, some preservatives, etc. turned out to be mutagens. Thus, the development of the chemical industry, along with great benefits, also creates a serious danger for humanity, since many chemicals connections damage the hereditary apparatus.

References

• Abilev S.K. Chemical mutagens and genetic toxicology // Genetics. - 2012. -№10. -WITH. 39-46
• Bochkov N.P. Clinical genetics. M.: Medicine. -1997. -WITH. 180.
• http://medbiol.ru/medbiol/genetic_sk/00071959.htm
• http://worldofschool.ru/biologiya/stati/genetika/izmenchivost/himicheskie-mutageny

“Genetic diseases” - Indications for amniocentesis. Classification of gene diseases. Hereditary diseases. Genealogical method. Gene mutations. X-linked recessive type of inheritance. Autosomal recessive type of inheritance. Marfan syndrome. Impaired hemoglobin synthesis. Classification of hereditary diseases. Galactosemia.

“Inherited genetic diseases” - “Cry of the cat” syndrome. Polyploidy. Patients with Shereshevsky-Turner syndrome. Down syndrome. Danlos syndrome. Marfan syndrome. Hereditary diseases. Neurofibromatosis. Edwards syndrome. Chromosomal diseases. Klinefelter's syndrome. Gene diseases. Maurice's syndrome. Cystic fibrosis. A delicate problem. Reproductive health protection.

“Medical genetics and the human genome” - Core. Recessive inheritance. Characteristics of the human genome. Cystic fibrosis. Monogenic hereditary diseases. Epigenetic diseases. General classification of genes. Diagnosis of gene diseases. Stages of implementation of genetic information. Mutation detection methods. Genome research. Hereditary diseases.

“Mutations and hereditary diseases” - Mutations. Down's disease. Statistics. Marfan syndrome. Turner syndrome. Hereditary human diseases. Cleft lip and palate. Practical genetics. Progeria. Klinefelter's syndrome. Phenylketonuria. Story. Meaning for an individual. Hemophilia. Albinism. Knowledge about types of mutations. Types of mutations.

“Examples of human chromosomal diseases” - Symptoms of Cry Cat Disease. Give a definition. Chromosome structure. Syndrome of polysomy on the Y chromosome. Inversion and ring chromosome. Triplo syndrome. Cry cat syndrome. Sex chromosome polysomy syndrome. Karyotype for Down syndrome. Human chromosomal diseases. Klinefelter's syndrome. Symptoms of the disease.

"Alzheimer's disease" - Diagnosis. Nootropics. Pathogenesis. Risk factors. Relevance. ICD-10 classification. Neurophysiological research. Clinical manifestations. Neuropsychological research. Intravital visualization of brain structures. Biochemical research. Replacement therapy. Prevalence. Etiology.

There are 30 presentations in total

We continue to talk about reactions involving DNA Replication (self-duplication of DNA) Recombination (exchange of sections between DNA molecules) Reparation (self-repair of DNA) Transcription (synthesis of RNA on DNA) Reverse transcription (synthesis of DNA on RNA - in some viruses) Mutation (change in the structure of DNA)

“Only those who do nothing make no mistakes” Popular wisdom During replication and recombination, various violations constantly arise in the structure of DNA and chromosomes, which are recognized and corrected by repair systems. Disturbances in these “three r's” can lead to mutations.

CTT in DNA GAA in RNA CAT in DNA GAA in RNA Missense mutation. An example is sickle cell anemia. The replacement of a pair of nucleotides led to the replacement of an amino acid in the protein, i.e. the primary structure changed, which led to a change in the secondary, tertiary and quaternary and shape of the red blood cells.

HBB gene defect (*141900, 11p15.5). HbS is formed as a result of the replacement of valine with glutamic acid at position 6 of the b-chain of the Hb molecule. In the venous bed, HbS polymerizes to form long chains, and red blood cells become sickle-shaped. This causes an increase in blood viscosity, stasis; a mechanical barrier is created in small arterioles and capillaries, which leads to tissue ischemia (which is associated with pain crises). Not for memorization!

A nonsense mutation can occur either as a result of a nucleotide substitution or a reading frameshift. Example: blood type 0. In people with this blood type, a loss (deletion) of one nucleotide occurred in the gene - as a result, a stop codon appeared. A short and inactive enzyme protein is synthesized.

Antigens A and B are oligosaccharides, synthesized from antigen H under the action of enzyme proteins A (allele I A) or B (allele I B). Mutation “0” in the gene (allele I 0) led to the formation of an inactive protein. H AB Group 0 (H) Group A (A) Group B (B) Group AB (A and B) Red blood cell membrane with different antigens

More examples of mutations with the loss of different numbers of nucleotides Deletion of 3 nucleotides - cystic fibrosis Deletions or insertions (insertions) of a large number of nucleotides - DMD and BMD - Duchenne (early and severe) or Becker (late and milder) muscular dystrophy Not for memorization!

Multiple allelism The longer a gene, the more mutant alleles it may have. As Leo Tolstoy wrote on another occasion: “All happy families (the norm) are equally happy. Each unhappy family (mutation) is unhappy in its own way.” Thus, about 1000 mutations of the cystic fibrosis gene have been identified, most of them rare. The most common mutation (50% of cases) – del 508 – leads to the loss of phenylalanine at position 508 of the protein and disrupts its function.

Genes have names and places on chromosomes (“registration”), for example: 15q21.1 – fibrillin (mutation causes Marfan syndrome) 07q31.2 – transmembrane regulator (mutation leads to cystic fibrosis) Xp21.2 – dystrophin (mutations – Duchenne or Becker myopathy ) Short arm p Long arm q Regions are numbered from the centromere to the telomeres in each arm

Genetic nomenclature (approach 1) is based on the description of changes in DNA or protein. Examples (no need to remember!): 3821delT - loss of thymine at position ins13 kb - after nucleotide 2112 a nucleotide (13 kilobases) was inserted delF508 - loss of phenylalanine at position 508 N44G - replacement of asparagine with glycine at position 44 W128X - replacement of tryptophan with a stop triplet AlanineAlanine A Ala ArginineArginine R Arg Aspartic acidAspartic acid D Asp AsparagineAsparagine N Asn ValineValine V Val HistidineHistidine H His GlycineGlycine G Gly Glutamic acidGlutamic acid E Glu GlutamineGlutamine Q Gln IsoleucineIsoleucine I Leucine L Ley Lysine K Lys Methionine in M ​​Met ProlineProline P Pro SerineSerine S Ser TyrosineTyrosine Y Tyr ThreonineThreonine T Tre TryptophanTryptophan W Three PhenylalaninePhenylalanine F Phen CysteineCysteine ​​C Cis Stop triplet X B DNA IN PROTEIN

Gene mutation numbers (OMIM) – Autosomal dominant – Autosomal recessive – X-linked – Y-linked – Mitochondrial – Autosomal, described after May 15, 1994 (OMIM - Online Mendelian Inheritance in Man) Each mutation receives a 6-digit number

The names of gene diseases are not systematized (approach 3) It may simply be a name based on the manifestation of the disease - achondroplasia - “underdevelopment of cartilage” There may be a syndrome named after the scientist (more often) - Marfan syndrome; or sick (less often) There may be a catchy and unusual name - Kabuki makeup syndrome, happy doll syndrome 45 Marfan syndrome OMIM Mutation in an important connective tissue protein - fibrillin. Manifestations – tall stature, long limbs, tensile joint. textile. As a consequence – scoliosis, lens subluxation*, aortic aneurysm**. *** ** *

Kabuki makeup syndrome OMIM, what the genetic defect consists of is not yet known

Since most mutations are harmful, nature has developed anti-mutation mechanisms Two strands of DNA (spare strand) Degeneracy of the genetic code (spare triplets) Presence of repeating genes (spare genes) Diploidy (spare set of chromosomes) Repair systems (monitors at the DNA level) Immune system (monitors at the DNA level) body)

Frequency of gene mutations Spontaneous mutations occur spontaneously throughout the life of an organism under normal environmental conditions. The method for determining the frequency of spontaneous mutations in humans is based on the appearance of a dominant trait in children if the parents do not have it. Scientist Haldane calculated the average probability of the occurrence of spontaneous mutations, which turned out to be equal to 5 x per gene (locus) per generation. Properties of a gene (not to be confused with the properties of the genetic code!) Discreteness (has a certain size and position - locus) Lability (can mutate) Stability (however, it rarely mutates) Specificity (the gene encodes a specific protein) Allelicity (variants appear as a result of mutations - alleles) Pleiotropy (multiplicity of action) Dosage of action (the more copies of the gene in the genotype (doses), the stronger the effect of the gene)

Definition.
Classification of gene mutations.
Nomenclature of gene mutations.
The meaning of gene mutations.
Biological antimutation
mechanisms.
6. Gene properties.
1.
2.
3.
4.
5.

We continue to talk about reactions involving DNA

Replication (self-doubling of DNA)
Recombination (exchange of sites between
DNA molecules)
Reparation (self-repair of DNA)
Transcription (RNA synthesis from DNA)
Reverse transcription (DNA synthesis using
RNA - in some viruses)
Mutation (change in structure
DNA)

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“Only those who do nothing make no mistakes” Popular wisdom

During replication and recombination
various
abnormalities in the DNA structure and
chromosomes that are recognized and
corrected by repair systems.
Violations in these “three R’s” can
lead to mutations.

Disturbances in one of the DNA chains –
This is not a mutation yet!
Mouton - the smallest
unit of mutation –
equal to a pair
complementary
nucleotides.

Gene mutations. Definition.

Let me remind you: The structure of the eukaryotic gene.

Gene mutations – any
sequence changes
gene nucleotides
Let me remind you: The structure of the eukaryotic gene.

unique - one
copy per genome
structural - encode
protein or tRNA or rRNA
Genes
regulatory - regulate the work
structural
repetitive

Classification of mutations

For the reason

Spontaneous - the reason is not clear
Induced - caused
mutagens
Mutagens are factors that cause
mutations:
physical – for example, temperature, radiation
chemical - for example, НNO2, mustard gas
biological - for example, viruses

By level

Genetic changes within one
gene
Chromosomal - structural changes
chromosomes
Genomic – changes in quantity
chromosomes
Today we are discussing
only gene mutations!

By mechanisms

Main types of gene mutations:
nucleotide substitution
insertion or deletion
nucleotides
O
turning nucleotides by 180
(pairs of nucdeotides are meant everywhere)

Consequences of substitutions or insertions/deletions of one pair of nucleotides (using the example of simple text)

Nucleotide substitutions do not necessarily lead to a change in the meaning of genetic information

Missense - changes
amino acid in protein
Silent - amino acid not
is changing
Nonsense - instead of a codon for
amino acids there is a stop codon

Examples of gene mutations in humans

Missense mutation. An example is sickle cell anemia.
The replacement of a pair of nucleotides led to the replacement of an amino acid in the protein,
i.e. the primary structure changed, which entailed a change
secondary, tertiary and quaternary and forms of red blood cells.
CTT in DNA
GAA to RNA
CAT in DNA
GUA in RNA

HBB gene defect (*141900, 11p15.5). HbS is formed by the replacement of valine with glutamic acid at position 6 of the b-chain

Not for memorization!
HBB gene defect (*141900, 11p15.5). HbS is formed in
as a result of the replacement of valine with glutamic acid in
position 6 of the b-chain of the Hb molecule. In the venous bed HbS
polymerizes to form long chains,
red blood cells become sickle-shaped. This causes
increased blood viscosity, stasis; mechanical is created
obstruction in small arterioles and capillaries, which leads to
to tissue ischemia (which is associated with pain crises).

A nonsense mutation can occur either as a result of a nucleotide substitution or a reading frameshift. Example: blood type 0.

Nonsense mutation may occur
as a result of nucleotide substitution,
and when the reading frame is shifted.
Example: blood type 0.
In people with this blood type
gene loss occurred
(deletion) of one nucleotide – in
As a result, a stop codon was created.
A short and
inactive enzyme protein.

Antigens A and B are oligosaccharides, synthesized from antigen H under the action of enzyme proteins A (allele IA) or B (allele IB).

Mutation "0" in the gene
(allele I0) led to the formation of an inactive protein.
Group 0 (H)
Group A (A)
Group B (B)
Group AB (A and B)
A
Red blood cell membrane with
different antigens
N
IN

Deletions and insertions of a large number of nucleotides are often a violation of recombination (unequal crossing over). Examples: syndrome

Large dropouts and insertions
the numbers of nucleotides are often
recombination disorder
(unequal crossing over).
Examples: Martin-Bell syndrome
(mental retardation, with
fragile X chromosome)

Mutations with the insertion of a large number of nucleotides – trinucleotide repeat expansion diseases

Fragile X syndrome (Martin-Bell syndrome). The greater the insertion of CGG repeats, the higher the degree of decline in intelligence.

FMR-1 gene
norm
premutation
complete mutation

More examples of mutations with loss of different numbers of nucleotides

Not for memorization!
Deletion of 3 nucleotides – cystic fibrosis
Deletions or insertions (insertions)
large number of nucleotides – DMD and
DMD – Duchenne muscular dystrophy
(early and severe) or Becker
(late and lighter)

Cystic fibrosis is inherited in an autosomal recessive manner. The most common mutation is the loss of 3 nucleotides (triplet 508)

Not for memorization!
The secretion of secretions by the glands is impaired

Organs affected by
cystic fibrosis (CF)
"Drumsticks" and
“watch glasses” – manifestations
chronic lung infection
Meconium ileus is a manifestation of CF

Large deletions (losses) in the dystrophin gene give rise to DMD (Duchenne muscular dystrophy), insertions (insertions) give rise to DMD (muscular dystrophy).

Becker's dystrophy).
Inherited X-linked
recessive
Not for memorization!

DMD

Let's continue the conversation about the classification of gene mutations

By localization in the gene. If a mutation occurs

in the coding part – protein synthesis
may change qualitatively
in the regulatory part - for example, in
promoter – change quantitatively
there will be nothing in the introns -
neutral (silent) mutation

By location on the chromosome

Autosomal - in autosomes
(non-sex chromosomes)
X-linked (on the X chromosome)
Y-linked (in Y)

By location in the cell

Nuclear
Cytoplasmic (few,
but severe mitochondrial diseases)
Mitochondria have
its roundabout
DNA

Mitochondrial diseases are transmitted through the maternal line and affect muscles, vision, and the nervous system

All our cellular
organelles from moms and dads
only contribute chromosomes

By location in the body

Somatic (in body cells, most often
- cancer) are not transmitted to children
Generative (in germ cells and
will appear only in descendants)

According to the consequences

Harmful
Useful
Neutral

By manifestation in phenotype

Dominant (manifested in the phenotype
immediately both homo- and heterozygous
condition)
Recessive (appears only in
homozygous state)

Multiple allelism

The longer the gene, the more it can
be mutant alleles.
As Leo Tolstoy wrote on another occasion:
“All happy families (the norm)
happy equally. Every unhappy
the family (mutation) is unhappy in its own way.”
Thus, about 1000 gene mutations have been identified
cystic fibrosis, most are rare.
The most common mutation (50% of cases) is del
508 – leads to the precipitation of phenylalanine in
position 508 of the protein and disrupts its function.

Nomenclature of gene mutations

Genes have names and places on chromosomes (“registration”), for example:

15q21.1 – fibrillin (mutation causes
Marfan syndrome)
07q31.2 – transmembrane regulator (mutation
leads to cystic fibrosis)
Xp21.2 – dystrophin (mutations - myopathy
Duchenne or Becker)
Numbering
districts is coming
from
centromere to
telomeres in
each shoulder
3
2
1
1
2
3
4
Short shoulder p
Long shoulder q

The nomenclature of genes and gene mutations is based on different approaches:

Approach 1: Genetic nomenclature (by
changes in DNA or protein)
For human genetic diseases:
Approach 2: Mendelian Inheritance in Man (OMIM)
Approach 3: Disease names

Genetic nomenclature (approach 1) is based on the description of changes in DNA or protein. Examples (no need to memorize!):

In DNA
3821delT - thymine deposition in
Item No. 3821.
2112ins13 kb – after nucleotide no.
2112 13,000 nucleotides were inserted
(13 kilobases)
IN PROTEIN
delF508 – loss of phenylalanine in
positions 508
N44G – replacement of asparagine with glycine
in position 44
W128X – replacement of tryptophan with stop
triplet
Alanin A Ala
Arginine R Arg
Aspartic
acid D Asp
Asparagine N Asn
Valin V Val
Histidine H His
Glycine G Gly
Glutamic
acid E Glu
Glutamine Q Gln
Isoleucine I Ile
Leucine L Leu
Lysine K Liz
Methionine M Met
Proline P Pro
Serine S Ser
Tyrosine Y Tyr
Threonine T Tre
Tryptophan W Three
Phenylalanine F Fen
Cysteine ​​C Cys
Stop triplet X

A huge role in collecting and describing gene mutations in humans belongs to Victor McKusick. He began work on compiling

mutation register.
(approach 2)
(October 21, 1921 – July 22, 2008),

(OMIM - Online Mendelian Inheritance in Man)
Each mutation gets
6 digit number
Gene mutation numbers
(OMIM)
1
100000–
199999
Autosomal dominant
2
200000–
299999
Autosomal recessive
3
300000–
399999
X-linked
4
400000–
499999
Y-linked
5
500000–
599999
600000–
Mitochondrial
6
Autosomal, described after 15
May 1994

The names of gene diseases are not systematized (approach 3)

It could just be a name
based on the manifestation of the disease -
achondroplasia – “underdevelopment of cartilage”
There may be a syndrome named after
named after a scientist (more often) – syndrome
Marfana; or sick (less often)
Can be catchy and unusual
name - Kabuki makeup syndrome,
happy doll syndrome

Achondroplasia (chondrodystrophic
dwarfism)
OMIM 100800
Mutation in the protein receptor k
growth factor
fibroblasts

Marfan syndrome
OMIM 154700
Mutation in
important protein
connecting
oh fabric –
fibrillin.
Manifestations –
tall,
long
limbs,
stretchable
conn. textile.
How
consequence -
scoliosis,
subluxation
lens*,
aneurysm Since most mutations are harmful, nature has developed antimutational mechanisms Two strands of DNA (spare strand)
Degeneracy of the genetic code
(spare triplets)
Presence of repeating genes (spare genes)
genes)
Diploidy (spare set of chromosomes)
Repair systems (monitors at the DNA level)
Immune system (monitors the level
body)

But it’s impossible to completely avoid mutations!

harm to
individuals
benefit for
evolution

Frequency of gene mutations

Spontaneous mutations occur
spontaneously throughout life
body in normal conditions
environment.
Method for determining the frequency of spontaneous
mutations in humans is based on the appearance in
children of a dominant trait, if
he is absent from his parents.
Scientist Haldane calculated the average
the likelihood of spontaneous mutations occurring,
which turned out to be equal to 5 x 10-5 per gene
(locus) per generation.

Gene properties

Properties of a gene (not to be confused with the properties of the genetic code!)

Discreteness (has a certain size
and position - locus)
Lability (can mutate)
Stable (but rarely mutates)
Specificity (the gene encodes a specific
protein)
Allelicity (as a result of mutations
variants arise - alleles)
Pleiotropy (plurality
actions)
Dosage of action (the more
copies of the gene in the genotype (doses), those
stronger gene effect)

Slide 1

Lesson “Causes of mutations. Somatic and generative mutations"
The lesson was prepared by the biology teacher of the Astrakhan Municipal Budgetary Educational Institution “Secondary School No. 23” Medkova E.N.

Slide 2

The epigraph for the lesson can be words from the famous fairy tale by A. S. Pushkin “The Tale of Tsar Saltan”
“The queen gave birth in the night to either a son or a daughter; Not a mouse, not a frog, but an unknown animal.” A. S. Pushkin

Slide 3

Slide 4

Motivation in the lesson:
Introductory speech by the teacher about the problem of the phenomenon of mutations in humans and in the reality around them Problematic questions: Why do mutations occur? Are mutations really that dangerous? Should we be afraid of them? Can mutations be beneficial? Are mutations necessary in nature?

Slide 5

Objective of the lesson:
deepen and expand knowledge about the molecular cytological bases of mutational variability based on the study of the main characteristics of mutational variability and the diversity of somatic and generative mutations; develop knowledge about mutagenic factors as causes of mutations based on knowledge from the course of physics and chemistry

Slide 6

Lesson objectives:
Answer the questions by studying: the concept of mutation and the classification of mutations, the characteristics of various types of mutations, Find out the causes of mutations in nature Summarize the lesson: The meaning of mutations in nature and in human life

Slide 7

Basic concepts:
Mutation, mutagenesis, mutagens, mutants, Mutagenic factors Somatic mutations Generative mutations
Additional Concepts
Ionizing radiation Ultraviolet radiation
Chromosomal, gene and genomic mutations Lethal mutations Semi-lethal mutations Neutral mutations Beneficial mutations

Slide 8

Definitions:
Mutation
Mutagens
Mutation (from Latin mutatio - change, change) is any change in the DNA sequence. Mutation is a qualitative and quantitative change in the DNA of organisms, leading to changes in the genotype. The term was introduced by Hugo de Vries in 1901. Based on his research, he created a mutation theory.
Mutagens are environmental factors that cause mutations in organisms

Slide 9

Mutations (according to the degree of genotype change)
Gene (spot)
Chromosomal
Genomic

Slide 10

Gene mutations:
A change in one or more nucleotides within a gene.

Slide 11

Sickle cell anemia -
a hereditary disease associated with a disorder in the structure of the hemoglobin protein. Red blood cells under a microscope have a characteristic crescent shape (sickle shape)
Patients with sickle cell anemia have an increased (though not absolute) innate resistance to malaria infection.

Slide 12

Examples of gene mutations
Hemophilia (incoagulability of blood) is one of the most severe genetic diseases caused by the congenital absence of coagulation factors in the blood. Queen Victoria is considered the ancestor.

Slide 13

ALBINISM – lack of pigment
The cause of depigmentation is the complete or partial blockade of tyrosinase, an enzyme necessary for the synthesis of melanin, a substance on which the color of tissues depends.

Slide 14

Chromosomal mutations
Changes in the shape and size of chromosomes.

Slide 15

Chromosomal mutations

Slide 16

Slide 17

Genomic mutations -
Change in the number of chromosomes

Slide 18

Genomic mutations -
An “extra” chromosome in pair 21 leads to Down syndrome (the karyotype is represented by -47 chromosomes)

Slide 19

Polyploidy
Hexoploid plant (6n)
Diploid plant (2n)

Slide 20

Human use of polyploids

Slide 21

Mutations are distinguished:
Visible (morphological) - short legs and hairlessness in animals, gigantism, dwarfism and albinism in humans and animals. Biochemical - mutations that disrupt metabolism. For example, some types of dementia are caused by a mutation in the gene responsible for the synthesis of tyrosine.

Slide 22

Slide 23

There are several classifications of mutations
Mutations are distinguished according to the place of occurrence: Generative - occurring in germ cells. They appear in the next generation. Somatic - occurring in somatic cells (cells of the body) and are not inherited.

Slide 24

Mutations by adaptive value:
Useful - increasing the vitality of individuals. Harmful - reducing the viability of individuals. Neutral - not affecting the viability of individuals. Lethal - leading to the death of an individual at the embryonic stage or after its birth

Slide 25

Slide 26

Mutations are distinguished:
Hidden (recessive) - mutations that do not appear in the phenotype in individuals with a heterozygous genotype (Aa). Spontaneous - spontaneous mutations are very rare in nature. Induced - mutations that occur due to a number of reasons.

Slide 27

Mutagenic factors:
Physical factors
Chemical factors
Biological factors

Slide 28

Questions for a conversation about physical mutagens:
1. What types of radiation do you know? 2. What radiation is called infrared? (let’s establish a connection between temperature and mutations) 3. Why is ultraviolet radiation called chemically active? 4. What is ionizing radiation? 5. What is the effect of ionizing radiation on living organisms?

Slide 29

Mutagenic factors:
Physical mutagens ionizing radiation ultraviolet radiation - excessively high or low temperature. Biological mutagens some viruses (measles, rubella, influenza virus) - metabolic products (lipid oxidation products);

Slide 30

Physical mutagens
Mutations due to the Chernobyl explosion Scientists have found that in the 25 years after the Chernobyl disaster, genetic mutations doubled the number of congenital anomalies in the descendants of people living in areas affected by radiation

Slide 31

Chemical mutagens:
- nitrates, nitrites, pesticides, nicotine, methanol, benzopyrene. - some food additives, for example, aromatic hydrocarbons - petroleum products - organic solvents - drugs, mercury preparations, immunosuppressants.

Slide 32

Exposure to chemical mutagens
Nitric oxide. A toxic substance that breaks down into nitrites and nitrates in the human body. Nitrites provoke mutations in body cells and mutate germ cells, leading to irreversible changes in newborns. Nitrosamines. Mutagens to which ciliated epithelial cells are most sensitive. Similar cells line the lungs and intestines, which explains the fact that smokers have a high incidence of lung, esophageal and intestinal cancer. Benzene. Constant inhalation of benzene contributes to the development of leukemia - cancer of the blood. When benzene burns, soot is formed, which also contains many mutagens.