home Investment Gene interaction multiple action presentation. Types of gene interactions. % of cats with white fur and blue eyes are deaf

Gene interaction multiple action presentation. Types of gene interactions. % of cats with white fur and blue eyes are deaf

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Of the purely human relationships that give rise to omnipresent life, that give birth to both joy and sorrow, there is the relationship between a woman and a man. Or you can say the opposite. Everything else, if you like, is derived from these relationships. Vasily Fedorov.

Subject. Genotype as an integral system. Gene interaction.

I need to figure it out myself. And to figure it out for yourself, you need to think together... Boris Vasiliev

Objectives: 1. Know: types of gene interactions, genetic terminology; 2. Understand the essence of various gene interactions; 3. Be able to: operate with genetic concepts, explain the integrity of the genotype; 4. Apply terms and concepts in everyday life situations. 5. Evaluate the results of gene interaction from the point of view of their significance for a particular organism.

Gene Trait Pleiotropic (from the Greek pleion - set and tropos - direction) or multiple action of a gene is the influence of one gene on the formation of several traits. Sign 1 Sign 3 2

Gene Trait Gene interaction is the influence of several genes on the development of one trait. Gen 1 Gen 3 2

Interaction of genes Non-allelic Allelic 1. Complementarity. 2. Epistasis. 3. Polymeria. 1. Complete dominance. 3. Codominance. 2. Incomplete dominance.

Express lottery! 1 2 3 4 5

Conclusions: 1. A genotype is a system of interacting genes. 2. The integrity of this system is characterized by the interrelation and consistency of biochemical and physiological processes. 3. Both allelic and non-allelic genes located in different loci of the same and different chromosomes interact with each other.

Creative task. Burime. Create a poetic work using rhymes: 1. Heredity is responsibility. 2. Locus - focus. 3. Genotype - phenotype. 4. Once - epistasis. 5. Pleiotropy is a utopia. 6. Complementarity – gratitude. 7. Century - man. Allowed: 1. Any sequence. 2. Using rhymes with other genetic terms. Evaluation criteria: 1. Content. 2. Euphony.

Complete dominance A – yellow color of peas a – green color of peas P ♀ AA ♂ aa yellow green gametes A a F 1 Aa yellow x

Incomplete dominance B – purple color of petals b – white color of petals P ♀ BB ♂ bb purple white gametes B b F 1 Bb pink x

Codominance I A – antigens A I B – antigens B is a type of interaction of allelic genes, in which heterozygous organisms exhibit both allelic genes. i 0 – absence of antigens Genotype Antigens on the surface of red blood cells Blood group i 0 i 0 0 (I) I A I A I A i 0 A (II) I B I B I B i 0 B (III) I A I B AB (IV) absence of antigens antigens A antigens B antigens A and B ( codominant)

(from Latin kompementum - addition) a type of interaction of non-allelic genes, in which a trait appears only in the case of the simultaneous presence of two dominant non-allelic genes in the genotype of an organism. A and B – normal hearing other options – deafness deaf gametes Ab aB Complementarity normal hearing (complementarity) P ♀ AAbb ♂ aaBB x F 1 AaBb

Epistasis (from the Greek epistasis - stop, obstacle) is a type of interaction of non-allelic genes, in which one gene suppresses the action of another non-allelic gene. S – suppresses I A and I B groups. blood 0 g. blood B gametes i 0 S I B s I A – antigens A I B – antigens B i 0 – absence of antigens s – does not suppress I A and I B gr. blood 0 (epistasis) P ♀ i 0 i 0 SS ♂ I B I B ss x F 1 I B i 0 Ss

(from the Greek poly - many) a type of interaction of non-allelic genes, in which the degree of manifestation of a trait depends on the number of dominant non-allelic genes in the genotype of the organism. A – dark skin color black woman white mulatto gametes AB ab a – light skin color B – dark skin color b – light skin color P ♀ AABB ♂ aabb x F 1 AaBb Polymeria

1 The integrity of the genotype is evidenced by the interaction of genes. How does it manifest itself?

The characteristics of any organism are determined by the proteins that make up the cells. Why is it believed that the formation of the characteristics of an organism occurs under the influence of genes? 2

What is the relationship between genes, proteins and characteristics of an organism? 3

The genotype cannot be considered as the sum of genes. Explain why? 4

What does the interaction and multiple action of genes indicate? What are the differences between these phenomena? 5

Types of gene interactions

Vologda Region,

Municipal educational institution secondary school No. 1, Gryazovets

Ivanova E.N.

Interaction allelic genes

Complete

dominance

Polymerism

Incomplete

dominance

Complementarity

Pleiotropy

Codominance

With complete dominance the dominant allele completely suppresses the effect of the recessive allele

With incomplete dominance the dominant allele does not completely suppress the effect of the recessive allele

( both alleles – dominant and recessive – exert their effect )

Intermediate inheritance with incomplete dominance

Codominance

When codominant (a heterozygous organism contains two different dominant alleles, for example I A and I B ), each of the dominant alleles exhibits its own effect, i.e. participates in the manifestation of the trait.

Epistasis

Suppression of the action of the genes of one allele by the genes of another

1. Dominant epistasis:

A suppresses B

2. Recessive epistasis

a suppresses B

Interaction of nonallelic genes

Epistasis

Task.

In oats black seed color is determined

dominant gene A,

gray – dominant gene B.

Gene A is epistatic to gene B,

the latter does not appear in his presence.

In the absence of genotype of both dominant

genes are manifested white color. Define:

aaВв – АаВв-

aavv- aavv

Aavv-

Epistasis

Interaction of nonallelic genes

Task.

Onions are recessive gene a in a homozygous state

prevents color development -

the bulbs remain white , gene A does not suppress coloring.

The specific color of the bulb depends on the genes:

B – red onion, c – yellow.

What will be the offspring from crossing two

Diheterozygous?

Complementarity

Interaction of nonallelic genes

Non-allelic genes do not manifest their effect separately, but with simultaneous interaction in the genotype they determine the development of a new trait

B – pea-shaped

A – pinkish

A + B – nut-shaped

av - simple

Interaction of nonallelic genes

Polymerism

A phenomenon where several non-allelic dominant genes are responsible for similar effects on the development of the same trait.

The more such genes there are, the more clearly the trait is manifested (skin color, cow milk yield)

Example

polymers

Task

If a black woman (A 1 A 1 A 2 A 2) and a white man (a 1 a 1 a 2 a 2) have children, then in what proportion can we expect children to appear - full blacks, mulattoes and whites?

The solution of the problem

Gene designation:

A 1, A 2 genes determining the presence of pigment

a 1 and 2 genes determining the absence of pigment

Interaction of nonallelic genes

Pleiotropy

(multiple allelism)

One gene influences the development of two

and more signs

C - black color

c – albinism

Cn – Himalayan color

C suppresses Cn, Cn suppresses c

Solve the problem: In a person, brown eyes and the presence of freckles are dominant signs. A brown-eyed man without freckles married a blue-eyed woman with freckles. Determine what kind of children they will have if the man is heterozygous for brown eyes, and the woman is heterozygous for freckles.

Both alleles - dominant and recessive - exhibit their effect, i.e. the dominant allele does not completely suppress the effect of the recessive allele (intermediate effect) Segregation by phenotype in F 2 1:2:1 Interaction of allelic genes Incomplete dominance

With codominance (a heterozygous organism contains two different dominant alleles, for example A1 and A2 or J A and J B), each of the dominant alleles exhibits its own effect, i.e. participates in the manifestation of the trait. Segregation by phenotype in F 2 1:2:1 Interaction of allelic genes Codominance

An example of codominance is human blood group IV in the ABO system: genotype – J A, J B, phenotype – AB, i.e. in people with blood group IV, both antigen A (according to the J A gene program) and antigen B (according to the J B gene program) are synthesized in red blood cells. P x II groupIII group G JAJA J0J0 JBJB J0J0 J A J 0 J B J 0 F1F1 J A J 0 J A J B J B J 0 J 0 II groupIV groupIII groupI group

Codominance is the inheritance of human blood groups in the ABO system. Codominance is the inheritance of human blood groups in the ABO system. A woman with blood type I gave birth to a child with blood type I. Will the court satisfy the claim against L. M, who has blood type IV? Answer: it won’t, since this couple cannot have a child with blood type I.

Problem: Inheritance of flower color in sweet peas. Crossing pure sweet pea lines with white flowers in F1 resulted in all red flowered individuals. And from crossing F1 - diheterozygous individuals of peas with red flowers, the result was _ with red flowers and _ with white flowers. A - - presence of propigment B - - presence of enzyme Complementarity Interaction of non-allelic genes P AAbb x aaBB white. white

In parrots, feather color is determined by two pairs of genes. The combination of two dominant genes determines the color green. Individuals that are recessive for both pairs of genes are white. The combination of the dominant gene A and the recessive gene b determines the yellow color, and the combination of the recessive gene a with the dominant gene B determines the blue color. Task: Complementarity Interaction of non-allelic genes

When crossing two dwarf corn plants, offspring of normal height were obtained. In F 2, from crossing F 1 plants with each other, 452 plants of normal height and 352 dwarf plants were obtained. Propose a hypothesis to explain these results, determine the genotypes of the original plants. Solve the problem:

Suppression of the expression of genes of one allelic pair by genes of another. Genes that suppress the action of other non-allelic genes are called suppressors. Dominant epistasis (segregation by phenotype 13:3) and recessive (segregation by phenotype 9:3:4) Epistasis Interaction of non-allelic genes

Task 2: In onions, the dominant gene A determines the presence of color in the bulbs (a - colorless bulbs), and gene B (b) determines the color of the bulbs (red color dominates yellow). Plants with white bulbs were crossed with each other. The resulting offspring included plants with colorless and red bulbs. Determine the genotypes of the parental forms and offspring. Epistasis Interaction of non-allelic genes

In chickens, gene C causes colored plumage, and its allele c causes white plumage. The dominant gene of another allelic pair (I) suppresses the manifestation of color, and the i gene allows the C gene to manifest its effect. A diheterozygous hen is crossed with a homozygous recessive rooster for both traits. What plumage color will the individuals in F 1 have? Solve the problem:

A phenomenon where several non-allelic dominant genes are responsible for similar effects on the development of the same trait. The more such genes there are, the more pronounced the trait (skin color, milk yield of cows) is. Interaction of non-allelic genes Polymerism

Problem If a black woman (A1A1A2A2) and a white man (a1 a1 a2 a2) have children, then in what proportion can we expect the birth of children - full blacks, mulattoes and whites? Solution to the problem Designation of genes: A1, A2 genes determining the presence of pigment a1, a2 genes determining the absence of pigment

Interaction of non-allelic genes Cooperation A phenomenon when, through the mutual action of two dominant non-allelic genes, each of which has its own phenotypic manifestation, a new trait is formed. Segregation by phenotype 15:1

Genotype

as a system of interacting genes

Z. M. Smirnova

The interaction of genes has a biochemical basis.

Gene interaction is the interaction of gene products in the cytoplasm. This is what determines the formation of the trait.

Gen 1

Gen 2

mRNA 1

mRNA 2

Interaction

(biochemical reactions)

Protein 2

Protein 1

Sign

Allelic – interaction of alleles of one gene

Multiple allelism –

genes present in a population in more than two allelic forms

Non-allelic - interaction of alleles of different genes

nonallelic genes

Codominance

Complete Domination

Overdominance

Incomplete dominance

Allelic genes are located in identical loci of homologous chromosomes

Complete dominance - interaction allelic genes, in which the dominant gene (A) completely suppresses phenotypic manifestation recessive gene(s)

For example, in humans the gene for brown eye color is dominant over blue.

R AA x ahh

100% brown eyes

Gametes ( G):

F 1

AA) This concept correlates with the effect of heterosis and is associated with such characteristics as viability, overall life expectancy, etc. 6" width="640"

Overdominance – appears when when the dominant allele in heterozygous

condition is more pronounced than in

homozygous state (Aa AA)

This concept correlates with the effect of heterosis and associated with symptoms such as viability, total duration life, etc.

With incomplete dominance of a heterozygote (Aa) have a phenotype intermediate between the phenotypes of the dominant (AA) and recessive homozygote (aa) .

Half of the individuals retain the parental phenotype - 1 (AA) : 2 (Aa) : 1 (aa),

and the second half of the hybrid offspring has an intermediate phenotype.

Example: a plant with the AA genotype has red flowers, and a plant with the aa genotype has white flowers, heterozygotes (Aa) have pink flowers.

F1 Aa

F 2

F 1

B F 2 split:

Incomplete dominance in humans

A number of genes that cause hereditary human diseases have the property of incomplete dominance, for example, sickle cell anemia . In people with the AA genotype, red blood cells have a normal shape,

with genotype Aa – suffer from sickle cell anemia. Children with the aa genotype die in infancy.

And also normal signs : For example,

human hair shape:

Curly. Direct

P♀AA × ♂ aa

100% wavy

when three or more genes occupying the same position (locus) in homologous chromosomes are responsible for one trait,

but these three genes are located in a combination of two in one allele in different individuals.

An example of such multiple alleles is the inheritance of blood groups in humans. The three alleles of the blood group gene are designated by the letters A( I A ), B( I B ) and O( i ). Alleles I A And I B are dominant, and the allele i recessive to both.

As a result, a person may experience

four different blood types.

Prevalence of ABO blood groups

A / IN

Inheritance of blood groups in humans

Allele A ( I )

Produces agglutinogen A

Allele B ( I )

Produces agglutinogen B

Allele O ( i )

Does not produce agglutinogen

Neither gene I A , neither gene I B do not dominate each other and find themselves in the same allele ( I A I B ) determine the synthesis of two agglutinogens in erythrocytes (IVgr).

The type of interaction when both genes each express themselves equally is called codominance.

I A I A ; I A i

I B I B ; I B i

I A I B

Genotype

Phenotype

group

Do children always inherit their parents' blood types?

IV ( AB) I(O)

P I A I B

I A

50% group II (A)

50% group III (B)

I A i

I B i

I B

Prevalence

Rh blood factor Rh(+) is an antigen that is found on the surface of red blood cells (erythrocytes). Approximately 15% of women do not have the Rh factor, i.e. are Rh negative Rh(-).

Threat of Rh conflict during pregnancy there is only if the woman is Rh(-), and the father of the unborn child is Rh(+). In this case, the child will most likely also be Rh(+). In this case, it may arise Rh conflict is an immune reaction due to which the mother’s body produces antibodies that destroy the baby’s red blood cells and cause the development of hemolytic disease of the newborn.

85 %

15 %

Rh (+)

Rh (-)

During repeated pregnancy, these antibodies penetrate into the blood of the fetus and cause the destruction of red blood cells that have the Rh(+) antigen. With each new antigen-incompatible pregnancy, the number of antibodies to the Rh(+) factor in the mother's blood increases.

Rhesus-

positive

fetal blood more often

total falls into

mother's blood flow

the process of childbirth,

but it is also possible in

case of any

interrupts

pregnancy,

when conducting

amniocentesis or

through small

cracks in

placenta. In blood

women

appear

antibodies to Rh(+)

factor.

2) and stimulate the formation of antibodies

3) Antibodies enter the fetal bloodstream

Antibodies

To Rh(+)

Mother

Rh( - )

A antigen

1) Rh(+) fetal red blood cells enter the mother's bloodstream

4) and cause destruction of red blood cells, leading to hemolytic disease

Epistasis

Complementarity

Pleiotropy

Polymerism

dominant

Non-cumulative

Cumulative

recessive

nonallelic genes

Non-allelic genes are located in different loci of homologous chromosomes or in different chromosomes.

Gene complementarity is a form of interaction of non-allelic genes in which genes, being in the same genotype, give a different phenotypic effect than each of these genes separately.

For example, chickens have several different comb shapes. Thus, when crossing purebred individuals with a “rose-shaped” (AAbb) and a “pea-shaped” (aaBB) comb, the offspring is obtained with a “nut-shaped” comb (AaBB):

"pink"

AA bb

"pisiform"

A b

A IN

A A IN b

"nutty"

IN F 2 Inheritance for comb shape is in the ratio 9: 3: 3: 1

AaB b

AB Ab aB ab

AAV b

AaBB

AaB b

AABB

A IN

A b

Ahh bb

AaB b

aaB b

AaB b

aaBB

AaBB

AaB b

ahh bb

aaB b

Ahh bb

In humans, one type of deafness may be determined by recessive genes dd or ee , which are located in different pairs of chromosomes.

Normal hearing is determined by two dominant non-alelic genes D And E , of which one determines the development of the cochlea, and the other of the auditory nerve. Dominant homozygotes and heterozygotes for both genes have normal hearing ( DDEE , DdEe ), recessive homozygotes for one of these genes are deaf.

In deaf parents with genotypes ddEE And DDee Children may be born with normal hearing.

R ddEE x DDee

F1 DdEe

Normal hearing was evident because two different ones combined in one genotype dominant genes which given qualitatively new sign – normal hearing.

Interferon formation in human cells associated with the complementary interaction of two non-allelic genes, localized in different chromosomes (one in the second, the second in the fifth chromosome).

Epistasis– a form of interaction of non-allelic genes in which one non-allelic gene suppresses the action of another gene.

The suppressing gene is called epistatic), the suppressed gene is called hypostatic.

Epistatic interaction of non-allelic genes can be dominant and recessive.

Black

White

AAbb X aaBB

AB Av aV av

AABV AAVv AaBB AaVv

AAVv Aavv AaVv Aavv

AaBB AaBB aaBB aaBB

AaVv Aavv aaVv aavv

A aBB

In dominant epistasis, one dominant gene suppresses the expression of another non-allelic dominant gene. Phenotypic cleavage during dominant epistasis can occur in the ratio 12: 3: 1, 13: 3, 7: 6: 3

In recessive epistasis, the recessive allele of the epistatic gene, being in a homozygous state, suppresses the action of the dominant (hypostatic) gene.

Phenotype splitting can occur in the ratio 9: 3: 4, 9: 7.

The recessive epistatic effect of genes can be found in the inheritance of blood groups in humans. The so-called Bombay phenomenon is that in a family where the father had blood type I and the mother had blood type III, a girl with type I was born. She married a man with blood type II and they had a girl with blood type IV. The appearance in the third generation of a girl with blood group IV from a mother with blood group I is explained by geneticists as a rare recessive epistatic gene (h), which in the homozygous state (hh) suppresses the expression of antigens on the surface of red blood cells.

I B iHh X iiHh

I B i hh X I A iHH

I B h

i h

I B h

I B H

i iHh

i iHH

I B iHh

I B iHH

I A I B Hh

I A H

I B i hh

i ihh

i iHh

I B iHh

i H

Polymerism manifests itself in the fact that one trait is formed under the influence of several genes with the same phenotypic expression. Such genes are called polymer genes.

Non-cumulative polymer –

When crossing shepherd's purse plants with triangular and oval fruits in F 1, plants with triangular-shaped fruits are formed.

When they self-pollinate in F2, splitting into plants with triangular and oval fruits in a ratio of 15:1 is observed.

This is explained by the fact that there are two genes that act uniquely. They are designated the same: A 1 and A 2. Then all genotypes (A 1 - A 2 -,

A 1 -a 2 a 2 , a 1 a 1 A 2 -) will have the same phenotype - triangular fruits, and only plants a 1 a 1 a 2 a 2 will differ - form oval pods.

F 1 A 1 a 1 A 2 a 2

The more polymer genes in an organism’s genotype, the more strongly the trait manifests itself, i.e., with an increase in the dose of the dominant gene

(A 1 A 2 A 3 etc.) its action is summed up, or cumulated.

For example, the degree of skin pigmentation in humans, determined by several pairs of genes, ranges from the maximum expressed in homozygotes for dominant alleles in all pairs (A 1 A 1 A 2 A 2 ) to a minimum in homozygotes for recessive alleles (a 1 A 1 A 2 A 2 ). When two mulattoes are married, heterozygous for all pairs, 1/16 of the offspring have maximum skin pigmentation (black), 1/16 have minimum skin pigmentation (white), and the rest are characterized by intermediate indicators of the expressiveness of this trait.

A 1 A 2

black woman

white

R A 1 A 1 A 2 A 2 X A 1 A 1 A 2 A 2

A 1 A 2

A 1 A 1 A 2 A 2

A 1 A 1 A 2 a 2

A 1 a 1 A 2 A 2

A 1 A 1 A 2 A 2

A 1 A 2

F 1 A 1 a 1 A 2 a 2

100% mulatto

A 1 A 1 A 2 A 2

A 1 A 2

A 1 A 1 A 2 A 2

mulatto

F 1 A 1 a 1 A 2 a 2 X A 1 a 1 A 2 a 2

A 1 A 1 A 2 A 2

A 1 A 2

A 1 A 1 A 2 A 2

Pleiotropy is the influence of one gene on the development of two or more traits (multiple gene action).

The phenomenon of pleiotropy is explained by the fact that genes with pleiotropic action control the synthesis of enzymes that participate in numerous metabolic processes in the cell and in the body as a whole and thereby simultaneously influence the manifestation and development of other characteristics.

Examples

1.40% of cats with white fur and blue eyes are deaf.

2. Phenylketonuria in humans (PKU)

Lack of the enzyme that converts phenylalanine into tyrosine, mental retardation, decreased pigmentation of hair and skin, eczema.

3. Arachnodactyly, caused by a dominant mutation, manifests itself simultaneously in changes in the fingers and toes, dislocations of the lens of the eye and congenital heart defects.

The leading role in genetic processes belongs to the nucleus and

chromosomes.

At the same time, the carriers of hereditary information are

and some cytoplasmic organelles (mitochondria and plastids),

which contain their own DNA. Such information

transmitted from cytoplasm and was named

cytoplasmic inheritance.

This information transmitted only through the mother's body,

because the egg cell of plants and animals contains many

cytoplasm, and the sperm is almost devoid of it.

The nucleus and chromosomes differ genetically

high resistance to changing environmental conditions

environment.

Chloroplasts and mitochondria develop to some extent

regardless of cell division,

directly responding to

environmental impact.

So they have

ability to provide fast

body reactions to change

external conditions

Plastid inheritance. Open German scientists K. Correns and E. Baur ( 1909 ) . Correns found that the color of the leaves (green or variegated) depends on the mother plant (maternal inheritance).

Due to mutations in variegated plants, some plastids are not able to form chlorophyll. During division, their plastids are distributed unevenly between daughter cells.

Mitochondrial inheritance. Ephrussi (1949) discovered in yeast.

Mutations of mitochondrial genes lead to mitochondrial cytopathies: Leber's disease (optic nerve atrophy), myo-, cardio-, encephalopathies.

Human mitochondrial diseases transmitted from mother to daughters and sons equally. Sick fathers do not pass the disease on to either their daughters or sons.