What is Dihybrid Cross?
The father of modern genetics, “Gregor Mendel,” was the first person to discover the principle of heredity. He conducted various experiments, including one on pea plants in his garden, and he observed how the pattern of inheritance changed from one generation to the next.
His experiment on peas helped him to propose his three laws of inheritance, named as follows:
- Law of Segregation: According to this law, when two features combine to form a hybrid pair, the two characters do not blend and remain distinct from one another. During the chromosome’s meiosis, each gamete obtains one of the two alleles.
- Law of Independent Assortment: This indicates that the two genes segregate independently of one another and other features during gamete development. According to the Law of Independent Assortment, each characteristic and character has a unique gene that influences and arranges itself independently of the other genes. This law also states that the genes are separately transferred from the parents to the offspring during the time of gamete and zygote production.
- Law of Dominance: According to this law, in a heterozygous scenario, the dominant allele is the one whose traits are expressed over the other allele, and the traits of this dominant allele are referred to as dominant traits. Dominant characters are those who appear in the F1 generation of characters. The F2 generation contains recessive traits.
First, Mendel studied one gene in the plant using a monohybrid cross. In this, he only considered a single character, which was the height of the plant on a pair of peas with one contrasting trait. And next, he studied about two genes in the plant using a dihybrid cross.
Characters with their Contrasting Traits
| Characters | Traits |
|---|---|
| Plant Height | Tall or Dwarf |
| Seed Shape | Round or Wrinkled |
| Seed Color | Yellow or Green |
| Pod Shape | Yellow or Green |
| Pod Color | Inflated or Constricted |
| Flower Color | Violet or White |
| Flower Position | Axial or Terminal |
What is a Dihybrid cross?
An experiment in producing two creatures that are identical hybrids for two qualities is a dihybrid cross. To put it another way, a dihybrid cross is a union of two organisms that are heterozygous for two separate features. People with this type of character are homozygous for that particular trait. Genes are DNA segments that control these features.
Different pairs of alleles for each trait are carried by the parents in a dihybrid cross. While the other parent carries a homozygous recessive allele, one parent is homozygously dominant. All of the offspring born following the crossings in the F1 generation are heterozygous for particular traits.
Example
Mendel crossed two features that were incompatible, such as the color and form of seeds, at a time. He crossed the spherical yellow seed and the green seed with wrinkles. In the F1 generation, he only succeeded in getting round yellow seeds. This demonstrated that seeds are often spherical and yellow.
In contrast, the seeds’ wrinkled shape and green color are distinct characteristics. F1 offspring were later self-pollinated. Four distinct seed combinations were produced as a result of the F2 generation. Within the phenotypic ratio of 9:3:3:1, there were wrinkled-yellow, round-yellow, wrinkled-green, and round-green seeds. He noticed a similar dominance and inheritance pattern during the monohybrid cross of these features. Hybridization also maintained the 3:1 phenotypic ratio of the round and wrinkled seed shape and the yellow and green seed color.
Consider the letters “Y” for seeds of yellow color, “g” for seeds of green color, “R” for seeds with a round shape, and “w” for seeds with a wrinkled shape. As a result, it is possible to deduce the parental genotype as “YYRR” (yellow-round seeds) and “year” (green-wrinkled seeds). Punnett Square Dimensions of 16 Make Dihybrid Cross Simple to Understand
FAQs on Dihybrid Cross
Question 1: Who is the father of modern genetics and the inventor of inheritance laws?
Answer:
Gregor Mendel is the father of modern genetics, and he is the inventor of inheritance laws, in which he proposed three laws named as follows:
- Law of segregation
- Law of independent assortment
- Law of dominance
Question 2: Why did Mendel select peas for his experiment?
Answer:
Mendel choose peas for his experiment:
- Peas have numerous varieties, and they have observable traits and characteristics.
- Peas can be simply cultivated in the garden without any special requirements except in the case of pollination.
- The pea has a long-life cycle with numerous offspring.
Question 3: Why is a dihybrid cross called a two-trait cross?
Answer:
Because this crossing involves two organisms that are identical hybrids for two traits, a Dihybrid cross is also known as a two-trait cross.
Question 4: Differentiate between monohybrid and dihybrid cross.
Answer:
A dihybrid cross is a cross between parents in which two pairs of opposing traits are analyzed simultaneously for the inheritance pattern, as opposed to a monohybrid cross, which is a cross between parents that differs by a single trait or where just a single trait is taken into account.
Question 5: How is the genotype of a dihybrid cross determined?
Answer:
The first step would be to establish a parental cross (P). Then create a 4×4 Punnett Square (or 16 squares) to see if the qualities are crossed.
By using lowercase letters for recessive traits and uppercase letters for dominant traits, determine the genotypes of the parents and assign letters to the alleles.Place the traits in the correct order on the square; logically, recessive traits can only exist if both parents also possess them. If both parents have the recessive characteristic “f,” for instance, the emerging trait will be (“ff”). The resulting characteristic will be “Ff,” not “fF,” if one of the parents has the letter “F” in their name.
Please Login to comment...