explain with the help of an example that traits are inherited independently.Write ratio in F1 and F2 generations and state the law based on it.
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Mendel conducted a dihybrid cross to study that traits are inherited independently. He considered two traits at a time: these were:- seed colour & seed shape in which Yellow colour (YY) and round shape (RR) is dominant over green colour (yy) and wrinkled shape (rr).
Mendel observed that the F2 progeny of dihybrid cross had a 9:3:3:1 as phenotypic ratio and produced nine plants with round yellow seeds, three plants with round green seeds, three plants with wrinkled yellow seeds and one plant with wrinkled green seeds. In this he found that round yellow and green wrinkled are parental combinations whereas round green and yellow wrinkled are new combinations.
In a dihybrid cross between two plants having round yellow (RRYY) and wrinkled green seeds (rryy), four types of gametes (RY, Ry, rY, ry) are produced. Each of these segregate independent of each other, each having a frequency of 25% of the total gametes produced.
From the experiment, he concluded that when two pairs of traits are combined in a hybrid, one pair of character segregates independent of the other pair of character. This is known as law of independent assortment.
Mendel observed that the F2 progeny of dihybrid cross had a 9:3:3:1 as phenotypic ratio and produced nine plants with round yellow seeds, three plants with round green seeds, three plants with wrinkled yellow seeds and one plant with wrinkled green seeds. In this he found that round yellow and green wrinkled are parental combinations whereas round green and yellow wrinkled are new combinations.
In a dihybrid cross between two plants having round yellow (RRYY) and wrinkled green seeds (rryy), four types of gametes (RY, Ry, rY, ry) are produced. Each of these segregate independent of each other, each having a frequency of 25% of the total gametes produced.
From the experiment, he concluded that when two pairs of traits are combined in a hybrid, one pair of character segregates independent of the other pair of character. This is known as law of independent assortment.
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AkashMandal:
sir, my ans is correct na
Very nice answer
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I explained, just the main points to understand well
As per my thoughts of PhD in Genetics
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The traits are inherited, independently can be explained by the Dihybrid cross, as per the experiments conducted byGregor John Mendel on pea plants.
(1) When The Tall plants with Round seeds were crossed with Dwarf plants having Wrinkled seeds --->
In F1 all plants are Tall with Round seeds.
So the Tallness and Round seeds are the traits governed by Dominant Genes. This is as per the Law of Dominance given by Mendel.
(2) When F1 plants that is Tall Plants with Round seeds ( TtRr Heterozygous ) are self pollinated ::---> In F2 generation four types of phenotyes are observed
(1) Tall Plants with Round seeds
(2) Dwarf Plants with Wrinkled seeds
Had these two phenotyes would observed, the Law of Independent Assortment could not be discovered by Mendel. BUT....BUT..
In F2
(3) Third phenotype
Long Plants with Wrinkled seeds And
(4) Fourth phenotype
Dwarf Plants with Round seeds
Are also observed:-------
The Tall Plants with Wrinkled seeds
And
The Dwarf Plants with Round seeds
In F2 generation proves that:::---->
Two Traits of (1)Tallness/Dwarfness
And (2) Round Seeds/ Wrinkled Seeds are inherited independently.
This is the proof of Mendel's
"* LAW OF INDEPENDENT ASSORTMENT*"
Hope it helps. Feels immense pleasure, while giving answers related to Genetics and Breeding. Thanks.
(1) When The Tall plants with Round seeds were crossed with Dwarf plants having Wrinkled seeds --->
In F1 all plants are Tall with Round seeds.
So the Tallness and Round seeds are the traits governed by Dominant Genes. This is as per the Law of Dominance given by Mendel.
(2) When F1 plants that is Tall Plants with Round seeds ( TtRr Heterozygous ) are self pollinated ::---> In F2 generation four types of phenotyes are observed
(1) Tall Plants with Round seeds
(2) Dwarf Plants with Wrinkled seeds
Had these two phenotyes would observed, the Law of Independent Assortment could not be discovered by Mendel. BUT....BUT..
In F2
(3) Third phenotype
Long Plants with Wrinkled seeds And
(4) Fourth phenotype
Dwarf Plants with Round seeds
Are also observed:-------
The Tall Plants with Wrinkled seeds
And
The Dwarf Plants with Round seeds
In F2 generation proves that:::---->
Two Traits of (1)Tallness/Dwarfness
And (2) Round Seeds/ Wrinkled Seeds are inherited independently.
This is the proof of Mendel's
"* LAW OF INDEPENDENT ASSORTMENT*"
Hope it helps. Feels immense pleasure, while giving answers related to Genetics and Breeding. Thanks.
Please read each word very carefully
Especially my words * Had these two phenotyes would observed, the Law of Independent Assortment could not be observed by Sir Mendel. BUT.. BUT..
nice answer sir
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