What are the three laws of Mendel?
Based on heridity and evolution chapter class 10....
If possible I need brief explanation of it
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Explanation:
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Answer:
Inheritance can be defined as the process of how a child receives genetic information from the parent. The whole process of heredity is dependent upon inheritance and it is the reason that the offsprings are similar to the parents. This simply means that due to inheritance, the members of the same family possess similar characteristics.
It was only during the mid 19th century that people started to understand inheritance in a proper way. This understanding of inheritance was made possible by a scientist named Gregor Mendel, who formulated certain laws to understand inheritance known as Mendel’s laws of inheritance.
Mendel’s Laws of Inheritance
Mendel’s Laws of Inheritance
Between 1856-1863, Mendel conducted the hybridization experiments on the garden peas. During that period, he chose some distinct characteristics of the peas and conducted some cross-pollination/ artificial pollination on the pea lines that showed stable trait inheritance and underwent continuous self-pollination. Such pea lines are called true-breeding pea lines.
Also Refer: Mendel’s Laws of Inheritance: Mendel’s Contribution
Why was Pea Plant Selected for Mendel’s Experiments?
He selected a pea plant for his experiments:
The pea plant can be easily grown and maintained.
They are naturally self-pollinating but can also be cross-pollinated.
It is an annual plant, therefore, many generations can be studied within a short period of time.
It has several contrasting characters.
Mendel conducted 2 main experiments to determine the laws of inheritance. These experiments were:
Monohybrid Cross Experiment
Dihybrid Cross Experiment
While experimenting, Mendel found that certain factors were always being transferred down to the offspring in a stable way. Those factors are now called genes i.e. genes can be called the units of inheritance.
Mendel’s Experiments
Mendel experimented on a pea plant and considered 7 main contrasting traits in the plants. Then, he conducted both the experiments to determine the aforementioned inheritance laws. A brief explanation of the two experiments is given below.
Monohybrid Cross
In this experiment, Mendel took two pea plants of opposite traits (one short and one tall) and crossed them. He found the first generation offsprings were tall and called it F1 progeny. Then he crossed F1 progeny and obtained both tall and short plants in the ratio 3:1. To know more about this experiment, visit Monohybrid Cross – Inheritance Of One Gene.
Mendel even conducted this experiment with other contrasting traits like green peas vs yellow peas, round vs wrinkled, etc. In all the cases, he found that the results were similar. From this, he formulated the laws of Segregation And Dominance.
Dihybrid Cross
In a dihybrid cross experiment, Mendel considered two traits, each having two alleles. He crossed wrinkled-green seed and round-yellow seeds and observed that all the first generation progeny (F1 progeny) were round-yellow. This meant that dominant traits were the round shape and yellow colour.
He then self-pollinated the F1 progeny and obtained 4 different traits wrinkled-yellow, round-yellow, wrinkled-green seeds and round-green in the ratio 9:3:3:1.
Check Dihybrid Cross and Inheritance of Two Genes to know more about this cross.
Dihybrd Cross
After conducting for other traits, the results were found to be similar. From this experiment, Mendel formulated his second law of inheritance i.e law of Independent Assortment.
Conclusions from Mendel’s Experiments
The genetic makeup of the plant is known as the genotype. On the contrary, the physical appearance of the plant is known as phenotype
The genes are transferred from parents to the offsprings in pairs known as allele.
During gametogenesis when the chromosomes are halved, there is a 50% chance of one of the two alleles to fuse with the other parent.
When the alleles are the same, they are known as homozygous alleles and when the alleles are different they are known as heterozygous alleles.
Also Refer: Mendelian Genetics
Mendel’s laws
The two experiments lead to the formulation of Mendel’s laws known as laws of inheritance which are:
Law of Dominance
Law of Segregation
Law of Independent Assortment
Law of Dominance
This is also called Mendel’s first law of inheritance. According to the law of dominance, hybrid offsprings will only inherit the dominant trait in the phenotype. The alleles that are suppressed are called as the recessive traits while the alleles that determine the trait are known as the dormant traits.