Question

Моногибридное задачи

Answer 1

№1
У мужчины карие глаза. У его жены голубые . Какие у них могут быть дети. ?при условии , что мужчина гомозигота по признаку карих глаз.
Фенотип ген генотип
карие        А       АА,Аа
 голубые     а       аа
Решение
Р мать аа * отец АА
G          а             А
F1  Аа - все дети будут иметь карие глаза.
Ответ: Аа - все дети будут иметь карие глаза.
№2
У томата красная окраска доминирует над желтой. Какое потомство можно ожидать от скрещивания гибридного растения и желтого растения.?
Фенотип ген генотип
красная    А  АА,Аа
желтая       а    аа
Решение
Р АА*аа
G   А / а
F1   Аа - гибридное растение.
Р2 Аа*аа
G    А.а/ а
F2 Аа.аа
     50%/50%
 красн/ желт
Ответ: половина потомства будет иметь красную окраску. половина желтую. 

Answer 2

Monohybrid Cross Problems

A monohybrid cross is a genetic cross between two individuals that differ in only one trait. This type of cross is used to study the inheritance of a single gene and its alleles. Let's dive into some detailed information about monohybrid cross problems.

In a monohybrid cross, the parents are usually referred to as the P generation (parental generation). They are crossed to produce the F1 generation (first filial generation), which consists of offspring that are hybrids for the trait being studied. The F1 generation is then crossed to produce the F2 generation (second filial generation), which allows us to observe the segregation and recombination of alleles.

The steps involved in solving monohybrid cross problems are as follows:

1. Determine the genotypes of the parents: The genotypes of the parents are usually given or can be inferred based on the information provided. For example, if one parent is homozygous dominant (AA) and the other parent is homozygous recessive (aa), the genotypes of the parents are known.

2. Determine the possible gametes: Each parent produces gametes that contain one allele for the trait being studied. For example, if the parents are AA and aa, the possible gametes for the AA parent are A, and the possible gametes for the aa parent are a.

3. Set up a Punnett square: A Punnett square is a grid used to predict the possible genotypes and phenotypes of the offspring. The alleles from one parent are written along the top of the square, and the alleles from the other parent are written along the side of the square. The possible combinations of alleles are then filled in the squares.

4. Determine the genotypes and phenotypes of the offspring: The genotypes and phenotypes of the offspring can be determined by examining the combinations of alleles in the Punnett square. The genotypes represent the genetic makeup of the offspring, while the phenotypes represent the observable traits.

5. Calculate the ratios: The ratios of the different genotypes and phenotypes can be calculated by counting the number of squares in the Punnett square that correspond to each genotype or phenotype.

Here's an example to illustrate the steps involved in solving a monohybrid cross problem:

Problem: In pea plants, the allele for tall (T) is dominant over the allele for short (t). If a homozygous tall plant (TT) is crossed with a heterozygous tall plant (Tt), what is the probability of producing a short plant (tt)?

Solution:

1. Determine the genotypes of the parents: - Parent 1: Homozygous tall (TT) - Parent 2: Heterozygous tall (Tt)

2. Determine the possible gametes: - Parent 1: T - Parent 2: T, t

3. Set up a Punnett square:

| | T | T | | ---- | ----- | ----- | | T | TT | TT | | t | Tt | Tt |

4. Determine the genotypes and phenotypes of the offspring: - Genotypes: TT, Tt, Tt, tt - Phenotypes: Tall, Tall, Tall, Short

5. Calculate the ratios: - Genotype ratio: 1 TT : 2 Tt : 1 tt - Phenotype ratio: 3 Tall : 1 Short

Therefore, the probability of producing a short plant (tt) in this cross is 1/4 or 25%.

Please note that the example provided is a simplified representation of a monohybrid cross problem. In reality, there may be additional factors to consider, such as incomplete dominance, codominance, or multiple alleles. The principles of Mendelian genetics can be applied to more complex scenarios as well.

I hope this explanation helps! Let me know if you have any further questions.