Mendel's Law of Inheritance ｜ 3 Mendelian Law of Inheritance ｜ Agri-Bio-Tech

Hi friends, welcome back. I'm Ganesh Thakur and you are watching video on Mendel's Law of Inheritance So before we proceed to Mendel's Law of Inheritance first, let's see something about Mendel and Why Mendel is known as father of genetics? So Mendel was born on 22nd July 1822 in Austria He did his higher studies in physics, mathematics and natural sciences in 1856 he started his famous experiment on garden pea and in 1865 he represented his paper experiments in plant hybridization at Natural History Society of Brune But Unfortunately his work remained unnoticed at that time later in 1900 three scientists that is Hugo de Vries, Karl Corenz and Eric Schermach rediscovered his finding independently Based on Mendel's principles Corenz postulated three laws that are known as Mendel's Law of Inheritance This opened a new field in biological science known as genetics and Mendel is known as father of genetics Now, let's see Mendel's Law of Inheritance Mendel's first law is law of dominance which says in a cross between two organisms pure for any pair of Contrasting character the character which appear in first Generation is called dominant and the one which is suppressed is called recessive In this cross recessive allele will always be masked by dominant allele therefore a cross between a homozygous dominant and a homozygous recessive will always express the dominant phenotype Thus there is always uniform expression in f1 generation Law of dominance can be explained with the help of monohybrid cross experiments So, let's see this monohybrid cross experiment What is the monohybrid cross? It is a cross between two pure parents differing in a single pair of contrasting character So, let's see this monohybrid cross experiment Mendel first selected some pure tall pea plant and pure dwarf pea plant and Then crossed them After crossing he found that all the plant in f1 generation were tall He started thinking where the dwarfness has gone Then he allowed natural selfing of all f1 hybrid and He found that dwarfness reappeared in some plants he got result that is all tall in f1 generation and tall and dwarf in f2 generation in the ratio of 3 is to 1 Then he concluded that only dominant character Expressed in f1 generation and not recessive character Curly hair in humans is also a good example of dominance over straight hair The law of dominance is significant and true But not universally applicable You know why? Because there are many cases where the dominance is not complete or absent and it shows Intermediate expression in f1 generation This is called incomplete dominance for example in 4 o'clock plant When red flower is crossed with white flower, it shows pink color in f1 generation That's why this law is significant and true, but not universally applicable Okay, can you tell me one more example of this incomplete dominance or co-dominance? If yes, then write in the comment box Now come to the topic from the reappearance of recessive character in f2 generation He concluded that in the f1 generation factors do not mix with each other But they remain together and during gamete formation these factors separate or segregate This is the second law of inheritance that is law of segregation So, let's see the law of segregation law of segregation or second law of inheritance says the allelic pair in a hybrid segregate or separate during the gamete formation and That during the formation of new gametes It receives only one of the two factors and are pure for a given trait Therefore this is also known as law of purity of gametes This law also can be explained with the help of monohybrid cross so Take the same example of cross between tall and dwarf pea plant in this the reappearance of recessive trait in f2 generation proves the law all sexually reproducing organisms are Deployed and gametes are applied This law is applicable for all organisms Therefore law of segregation is universally applicable Mendel's third law of inheritance is based on dihybrid cross so First, let's see. What is dihybrid cross? Dihybrid cross is a cross between two pure parents differing in two pairs of contrasting character so Let's see the Mendel's third law that is law of independent assortment Mendel's third law states that the alleles of two or More different genes get sorted into gametes independently of one another in other words when a dihybrid forms gamete Assortment of alleles of different rate is independent of their original combination in the parents Now let's see dihybrid cross experiment performed by Mendel first Mendel selected a variety of pea plant having yellow and round seeds and another variety having green and wrinkled seeds He performed artificial cross and found that all seeds of f1 generation were yellow and round He then allowed selfing of f1 generation plants and Surprisingly, he find that seeds were of four type that is yellow round yellow wrinkled green round and green wrinkled in the ratio of 9 is to 3 is to 3 is to 1 out of four types two were parental combination and two were new The appearance of these new combination in f2 generation proves the law of independent assortment The law of independent assortment is applicable only for those trait Which are on different chromosomes and not for those which are on same chromosome Thus law of independent assortment is not universally applicable So that's all in this topic Share this video more stay with us and don't forget to subscribe our channel agri biotech. 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