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From purely human relations, Giving life to the omnipresent course, Giving birth to both joy and sorrow, There are relations between a woman and a man. And you can say the opposite. Everything else, if you like, is derived from these relationships. Vasily Fedorov.

Topic. The genotype as an integral system. Interaction of genes.

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

Objectives: 1. Know: types of gene interaction, 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 situations Everyday life. 5. Evaluate the results of gene interaction in terms of their significance for a particular organism.

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

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

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

Express - lottery! 1 2 3 4 5

Conclusions: 1. Genotype is a system of interacting genes. 2. The integrity of this system is characterized by the relationship 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 poetic work, using rhymes: 1. Heredity - responsibility. 2. Locus - focus. 3. Genotype - phenotype. 4. Once - epistasis. 5. Pleiotropy is a utopia. 6. Complementarity - gratitude. 7. Century - a person. Allowed: 1. Any sequence. 2. Use of rhymes with other genetic terms. Evaluation criteria: 1. Content. 2. Sympathy.

Complete dominance A - yellow peas a - green 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 type of interaction of allelic genes, in which both allelic genes are manifested in heterozygous organisms. i 0 – absence of antigens Genotype Antigens on the surface of erythrocytes 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 lat. kompementum - addition) a type of interaction of non-allelic genes, in which the trait manifests itself only in the case of the simultaneous presence of two dominant non-allelic genes in the genotype of the organism. A and B - normal hearing other options - deafness deaf 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 gr. blood 0 gr. blood B gametes i 0 S I B s I A - antigens A I B - antigens B i 0 - lack 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 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 traits of an organism? 3

The genotype cannot be viewed as the sum of genes. Explain why? four

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

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

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

When codominating (a heterozygous organism contains two different dominant alleles, for example A1 and A2 or J A and J B), each of the dominant alleles shows its effect, i.e. involved in the expression of the trait. Phenotype segregation in F2 1:2:1 Interaction of allelic genes Codominance

An example of codominance is the IV human blood group in the ABO system: genotype - J A, J B, phenotype - AB, i.e. in people with IV blood group, both antigen A (according to the J A gene program) and antigen B (according to the J B gene program) are synthesized in erythrocytes. P x II group III 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 group IV group III group I 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 I blood group had a child with I blood group. Will the lawsuit against L.M, who has IV blood type, be satisfied by the court? Answer: no, because this couple cannot have a child with I blood group.

Task: Inheritance of flower color in sweet peas. From crossing pure lines of sweet peas with white flowers in F1, all individuals with red flowers turned out. And from crossing F1 - diheterozygous individuals of peas with red flowers, they turned out _ with red flowers and _ with white ones. A - - presence of propigment B - - presence of enzyme Complementarity Interaction of non-allelic genes white

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

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

Suppression of the manifestation of the genes of one allelic pair by the genes of another. Genes that suppress the action of other non-allelic genes are called suppressors (suppressors). Dominant epistasis (phenotype splitting 13:3) and recessive (phenotype splitting 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 the gene B (b) determines the color of the bulbs (red dominates over yellow). Plants with white bulbs were crossed among themselves. In the resulting offspring were plants with colorless and red bulbs. Determine the genotypes of parent forms and offspring. Epistasis Interaction of non-allelic genes

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

The phenomenon when several non-allelic dominant genes are responsible for a similar effect on the development of the same trait. The more such genes, the more pronounced the trait (skin color, milk yield of cows) Interaction of non-allelic genes Polymeria

Problem If a black woman (A1A1A2A2) and a white man (a1 a1 a2 a2) have children, then what proportion can be expected to have children - complete blacks, mulattoes and whites? Solution of the problem Designation of genes: A1, A2 genes that determine the presence of pigment a1, a2 genes that determine the absence of pigment

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

Berezina Galina Anatolyevna

Lesson topic: Interaction of genes and their multiple action

Target: to form ideas about the interaction of genes, their multiple action

Lesson objectives:

to activate students' knowledge about complete and incomplete dominance, inheritance of human blood groups;

to acquaint students with the types of interaction of allelic and non-allelic genes;

give an idea of ​​the multiple action of genes;

introduce the following concepts: "codominance", "complementarity", "epistase", "polymeria", "multiple action of genes";

consolidate the acquired knowledge in the course of performing tasks of various types;

to continue the practice of solving problems in genetics (incomplete dominance and polymerization).

development of cognitive interest in the subject;

contribute to increasing the motivation for learning.

Lesson type: combined.

Methods and techniques: illustrative-verbal

Equipment and materials: presentation "Interaction of genes".

During the classes:

Mendel, studying patterns of inheritance, proceeded from the assumption that one gene is responsible for one trait. For example, one gene is responsible for the development of the color of peas, but does not affect the shape of the seeds. These genes are located on different chromosomes and are inherited independently of each other.

But in the future, scientists found that there are complex relationships between genes and traits. Chromosomes contain not one, but many genes and they can interact with each other.

We write down the topic of the lesson "Interaction of genes and their multiple action."

3. Learning new material

Today we will consider two types of gene interaction - the interaction of allelic genes and the interaction of non-allelic genes.

Let's start by recalling once again what allelic genes mean, and what do non-allelic genes mean, respectively?

And let's start with the interaction of allelic genes, especially since this is familiar to us, although in a slightly different plane.

2 genetic schemes are offered (with drawings of plants).

Complete dominance Incomplete dominance

A - yellow seeds A - red flowers

a - green seeds a - white flowers

R ♀ AA × ♂ aa R ♀ AA × ♂ aa

yellow green red white

F 1 Aa F 1 Aa

yellow pink

F 2 AA: 2Aa: aa F 2 AA: 2Aa: aa

yellow yellow green red pink white

Phenotype split: 3:1 Phenotype split: 1:2:1

In either case, two homozygotes (dominant and recessive) are crossed.

Explain why in the case of "peas" the first generation hybrids exactly correspond in phenotype to one of the parents. And in the case of the “night beauty”, the hybrids of the first generation showed a completely different trait that did not correspond to any of the parents.

Additional question (if necessary). How do alleles "A" and "a" behave in a heterozygote in relation to each other?

We write in a notebook:

I

1. Complete dominance - only the dominant trait appears, but the recessive trait does not.

Example: coloring of pea seeds.

2. Incomplete dominance - hybrids have an intermediate nature of inheritance.

Example: coloring flowers of the night beauty. In the heterozygous (Aa), the dominant allele (A) suppresses the manifestation of the recessive (a) completely with complete dominance and incompletely with incomplete dominance. (The second part of the definition, I first ask the students to verbally formulate in detail, and then briefly write down).

What is another word for incomplete dominance?

Indeed, another name for "incomplete dominance" is "intermediate inheritance" and many take it literally as in the case of the beauty of the night (white × red → pink). But this is far from true. For example, Andalusian chickens (AA - black plumage, aa - white, and Aa - blue); mink (AA - dark fur, aa - white, and Aa - light color with a dark cross); horse (AA - white color, aa - bay, and Aa - golden yellow).

Let's conclude: F1 hybrids have a new trait that is not characteristic of their parents.

3. Co-dominance- hybrids exhibit two characteristics. This is how the blood type is inherited. It is determined by the presence of antigen molecules on the surface of erythrocytes. The gene exists in 3 alleles - A, B, O.

Combining two by two, these genes give six genotypes: AA, OO, AB, AO, BB, BO.

Alleles 00 - 1 group, no antigen.

AA, AO - group 2, antigen A.

BB, VO - group 3, antigen B.

AB- 4 group, antigen A, B.

Gene O is recessive. Genes A and B dominate the O gene, but do not suppress each other.

“The court hears the case on the recovery of alimony. Mother has I blood group, children - II, III. Can a man with IV blood type be the father of children?

Questions for drawing.

1. How many alleles that determine blood groups are known in the immunogenetic gene "I"? Name them.

2. What combination of alleles gives the fourth blood type?

3. Give a description of this genotype.

In this case, there is a joint participation of both dominant alleles (A and B) in determining the trait, that is, the fourth blood group. This manifestation of the interaction of allelic genes is called co-dominance(from the Latin "co" - "with", "together").

II . Interaction of allelic genes:

1. Complementarity– BUT) 2 non-allelic genes, being simultaneously in the genotype, lead to the formation of a new phenotypic trait. No gene has independent expression.

Example 1: deaf parents - hearing child.

PAAbb * aaBB

G Ab aB

F1 A аВb - hearing

F2 9A-B-: 3 aaB-: 3A-bb: 1aabb

Hearing deaf deaf deaf

9:7

B) one gene has an independent phenotypic manifestation, and the other does not. When these genes interact, a new phenotypic effect arises. 9:3:4

Example 2: staining mice, rabbits

A - the presence of pigment

B - distribution of pigment at the base of the hair

9 (A-B-) gray: 3 (A-cc) black: 4 (aaB-) white

Onion scale coloring

9 (A-B-) red: 3 (A-cc) yellow: 4 (aaB-; aavb) white

AT) each gene controls its own trait, but when dominant alleles are combined, a new phenotypic effect arises 9:3:3:1

Comb inheritance in chickens:

R - pink;

N - pea-shaped;

R -N - - walnut

r r n n - leaf-shaped

G) two genes of the same action when interacting give a new phenotype 9:6:1

Example: the shape of the fruit of a pumpkin: A- and B- separately - spherical (AAvv, aaBB), disc-shaped (A-B-), elongated (aavv).

2. Epistasis - one gene suppresses action of another gene

Suppressor gene - inhibitor, suppressor, epistatic

Gene suppressed - hypostatic

Example: the shape of flax petals. A is an inhibitor. 13 normal (A-B-, A-cc, aavv): 3 corrugated (aaB -)

Coloring of chickens: white leghorns + white plymouthrocks

13 white: 3 dyed

13:3

Coloration of horses: 12 gray (S-B-): 3 (black): 1 red (ssvv)

Oregano has a gene of male sterility according to the type of epistasis AaB- A-B- flowers bisexual, A-cc male sterile, aavv - lethal.

3. Polymeria - on the example of human skin.

Albinism (from the Latin "albus" - white) is the absence of normal pigmentation (coloration) of the integument. It is found in representatives of various kingdoms of wildlife (I give examples).

Albinos are also found among people, but quite rarely (approximately 1/20, or even 40,000 people). They have white hair, very fair skin, pink or light blue irises. These people are homozygous for the recessive gene "a", the dominant allele of which "A" is responsible for the production of melanin pigment in the body. With the help of melanin, the skin, hair and eyes of a person acquire color.

But it turns out that in humans, the formation and distribution of melanin also depend on a number of other genes. For example, the dominant gene "F" causes a patchy accumulation of melanin, that is, what we call freckles. And another dominant gene "P" causes a violation of pigmentation, due to which certain areas of the skin (sometimes quite large) remain light, unpigmented.

A number of other genes affect the amount of melanin in the human body, providing different shades of skin, hair, and eye color.

Differences in skin color between representatives of the Negroid and Caucasian races are determined by two pairs of genes (i.e. 4 in total) that affect the amount of melanin. This interaction of genes is called polymerium(unambiguous action of genes).

Polymeria - the more dominant genes, the more pronounced the trait.

For example, two pairs of genes determine differences in human skin color (the M. Jackson family); human height is determined by 10 pairs of genes (the more dominant genes in the genotype, the lower the person).

Whose height is greater? Explain the answer.

ssssssssssssssssssssssssssssssssssssssssssssssssssssssssssss...

Questions for the class:

1. Determine skin color (phenotype) by genotype. Explain the answer.

a) AABB, AABB, AABB;

2. Whose skin is darker. Explain the answer.

b) AABB, AaBv, aaBv, aavb;

c) AABB, AABB, AABB (trick question).

Scheme "Interaction of genes"

Gen 2 Gen 2

Gene interaction ↓

↓ ↓ Gene 1→ one trait

allelic non-allelic

Gen 3 Gen 3

1. Complete dominance 1. Polymeria (unique action of genes)

2. Incomplete dominance 2. Complementary interaction of genes -

3.COdominance- a joint participation for developmentnew trait requires both dominant alleles in the definitionsimultaneous the presence of two

trait (blood group 4 - AB) in dominant non-allelic genes.

heterozygote. 3. Epistasis - suppression of the action of one

gene to another, non-allelic (dominant)

or recessive).

Multiple actions of genes.

→ Gene 1 → trait

One gene → Gene 2 → trait

→ Gene 3 → trait

PHENOTYPE = GENOTYPE + ENVIRONMENT

Of course, there are more types of gene interaction than we have considered today in the lesson. You can safely add at least two more: complementary interaction of genes and epistasis. But you will go through this in detail in high school. You can see a generalized scheme reflecting the essence of the interaction of genes at the top right. Explain it (several genes - allelic and non-allelic - determine the development of any one trait of the organism).

III . Multiple action of genes:

And now about another curious phenomenon in genetics - the multiple action of genes. Let's start with an example.

A person has a gene that determines red hair color. The same gene determines two more traits. Try to name them (lighter skin coloration and freckles).

In this case, one and the same gene can influence the formation of a number of traits of an organism, which is typical for most genes (transcription products of any gene can be used in various developmental and growth processes intertwined with each other).

We sign in the scheme "Multiple action of genes" specific example with red hair, fair skin and freckles.

Allelic genes are located on different chromosomes and are responsible for the same trait. The inheritance of allelic genes is independent of each other (like the color and shape of pea seeds)

4. Consolidation of the studied material

We open the inscription on the board: "The gene determines the development of the trait"

Familiar wording. How would you react to this expression now? Personally, it seems to me rather conditional. Confirm or refute it (listen to several opinions of students).

The relationship between genes and the manifestation of a trait is much more complex than it seems at first glance. They depend on the location of genes in the chromosome and on their behavior in mutations, on the combination of allelic and non-allelic genes, and, finally, on the impact environment(We will talk about this in later lessons). For example, in the dark, a potato tuber does not form chlorophyll, despite the presence of the corresponding genes. However, it is worth bringing a potato tuber into the light, and the genes will manifest themselves. And the last. Look at the diagram "Phenotype = genotype + environment". How do you understand it?

Right. The phenotype, that is, the manifestation of a trait, is the result of the interaction of the genotype, that is, the totality of all the genes of the organism and the environment (given, specific, possibly changing). The genotype in a variety of conditions is able to be realized in different ways, which increases the organism's chances of survival.

6. Homework

§ 22; compose and solve a genetic problem for the inheritance of blood groups in your family

slide 2

A gene is a structural unit of hereditary information that controls the development of a certain trait or properties.

slide 3

Gene - material carrier hereditary information, the totality of which parents pass on to their offspring during reproduction.

slide 4

• Gene Interaction
• Complete dominance
• incomplete dominance
• Polymerism
• complementarity
• Codominance
• Cooperation
• epistasis