Hybrid

Man since the early civilisation used the concept of selective breeding for animals. But no proper scientic data was recored. In the eighteenth century an Austrian Monk first did proper research and analysis and reported a proper format for cross

Man since the early civilisation used the concept of selective breeding for animals. But no proper scientic data was recored. In the eighteenth century an Austrian Monk first did proper research and analysis and reported a proper format for cross breeding and their traits.

article1Gregor Mendel(1822 – 1884) is known as father of Genetics. He was a monk who used mathamatics into plant genetics and he was not recognized for his work during his lifetime. His works had been published in the year 1866 but went unrecognized until 1900, which was fourteen years after his death.

He used common edible peas for his hybridization experiments. He was very much sucessful with them. Mendal success was mainly of two reasons one is the plant he had choosen peas. In which the traits were easily seen in the naked eye and the life cycle of the plants are small.

By selective cross-breeding of the common pea plants (Pisum sativum). Mendel observed that certain traits show up in offspring without any blending of the original parent characteristics. For instance, the pea flowers are either purple or white–intermediate colors do not appear in the offspring of cross-pollinated pea plants.

Mendal Observed Seven Different tratis in common peas

1. Flower Colour : There was two colours white & Purple

2. Flower position in the plants : In the end of the creeper (Terminal) or in intermediate stems (axil)

3. Stem Length : The length between any two leaves in the plant, that can be long or short

4. Seed Shape: The seed coat is round or wrinkled

5. Seed Color: There were yellow or green seed coat colors

6. Pod shape: The pod which hold the seeds were inflated or constricted

7. Pod Color: They were yellow or green seed pod colors

Mendel summarized his findings in two laws; the Law of Segregation and the Law of Independent Assortment.

Law of Segregation (The “First Law”)

The Law of Segregation states that when any individual produces gametes, the copies of a gene separate so that each gamete receives only one copy. A gamete will receive one allele or the other. The direct proof of this was later found when the process of meiosis came to be known. In meiosis the paternal and maternal chromosomes get separated and the alleles with the traits of a character are segregated into two different gametes.

Law of Independent Assortment (The “Second Law”)

The Law of Independent Assortment, also known as “Inheritance Law”, states that alleles of different genes assort independently of one another during gamete formation. While Mendel’s experiments with mixing one trait always resulted in a 3:1 ratio (Fig. 1) between dominant and recessive phenotypes, his experiments with mixing two traits (dihybrid cross) showed 9:3:3:1 ratios (Fig. 2). But the 9:3:3:1 table shows that each of the two genes are independently inherited with a 3:1 ratio. Mendel concluded that different traits are inherited independently of each other, so that there is no relation, for example, between a cat’s color and tail length. This is actually only true for genes that are not linked to each other.

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One Response to Hybrid

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