How Did Gregor Mendel Determine The Law Of Monohybrid Inheritance

Gregor Mendel
Gregor Mendel was a nineteenth-century Austrian monk who is widely regarded as being the founder of genetics in modern science. There had been existing knowledge that crossbreeding plants and animals could enable the desired characteristics to be passed on. However, it was his groundbreaking discoveries he made via pea plant experiments conducted by him over 1856 to 1863 that showed how certain traits are passed on to next generation. Over this time period he is said to have tested over 5000 pea plants and from this he derived the law of Mendelian Inheritance
He was able to predict the probabilities of certain characteristics being passed onto the offspring of plants. He showed that certain factors, now known as genes, affected
what the outcomes could be. He did this by working with seven different characteristics of plants which included plant height, pod shape and color, seed shape and color, and flower position and color. By breading the plants with similar and different characteristics, he was able to pick up the trend in probabilities of inheriting certain traits which he called dominant and recessive.
Mendel had been working with plants and animals on a family farm from an early age. Throughout his earlier carrier and education he met a considerable number of people that were conducting research on genetics and this influenced him to follow their steps. Furthermore, he was authorized to work in the monasteries experimental garden, were he conducted the vast majority of his studies on plants.
Mendel came to determine the principles of monohybrid inheritance by incorporating the three laws he formed into his studies.
The law of segregation states that when the gamete is being produced, each allele for each gene is carried on a single gamete so that the alleles for each gene have been segregated from one another. It is during fertilisation when the two gametes fuse that the pairing of the alleles occurs. The second law of independent assortment suggests that the genes for different characteristics are separated independently during the production of gametes. The third law of dominance says that alleles can be dominant or recessive. However, it is only the dominant alleles that will be expressed in the phenotype if it is present. In a cross pollination experiment between yellow and green pea plants exclusively, the first generation offspring was always yellow. However, the second generation consistently produced offspring in a ration of 3:1. This ration continued though out further generations. This means the first generation was homozygous but the second became heterozygous. These laws and experiments underline monohybrid inheritance because they form the basis of the punnett square, a visual representation of Mendelian Inheritance, which represents the probabilities of certain alleles being
expressed.
Cystic Fibrosis is an autosomal recessive disorder that is caused by mutations in certain genes. Carriers of the disease have one working gene that is expressed. Sufferers of the disease however, have no working genes so they express two homozygous recessive alleles that cause cystic fibrosis. The law of segregation supports this because two carriers who have segregated gametes carry each allele for the gene which can result in the production of offspring that can be a suffer, carrier or not have the gene at all. The law of independent assortment also supports this as each gamete and therefore allele is independent from one another. The law of dominance also suggests that because the alleles for cystic fibrosis are recessive, they have to be homozygous recessive to be expressed.