Gregor Mendel is known as the “father of genetics” due to his hard work and dedication to show why people and things look the way they do. Mendel had a great curiosity in how different generations of offspring contain certain aspects of appearance from both parents. To study this Mendel used pea plants or Pisum sativum. He chose to work with this for many reasons as pea plants are a great model organism. Some of these reasons include flower size, the idea that they can both be self, and cross- fertilized and that there were many different traits mendel could breed for.
Mendel started his experiments in 1856 on a small plot of land. There were seven characteristics that mendel bred for, those were height, flower color, flower position, seed color, seed shape, pod color, and pod shape. Through different crosses he came up with the idea that some traits are dominant to others and will show up more often than others depending on the genotype of the parents. Mendel worked for a long time crossing and recrossing pea plants and writing down all his discoveries.
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This led to the law of inheritance. (Brooker, 2016) Mendel’s Laws of inheritance explain what goes on during meiosis. The law of segregation states that two copies of a gene from each parent will separate to different offspring and his law of independent assortment states that two different genes randomly sort there alleles while forming haploid cells. Both of these laws make up the laws of inheritance which play a big role in genetics. (Brooker, 2016) During Mendel’s time there was much disbelief about what he was studying because of the things that still weren’t discovered. For example, when Mendel was experimenting with pea plants meiosis was not known at the time.
All of his work went unnoticed until 1900, which was sixteen years later. Even though his ideas were not discovered until later on, Mendel died knowing his work would be taught throughout the whole world. Having a basis of understanding from Mendel’s work has helped other scientist make knowledge about genetics what it is today. (Brooker, 2016) The organism that mendel used to study was the pea plant, Pisum sativum, which was a great model organism for many reasons. There are also many other great model organisms that scientist have used for testing. One of these model organisms include the fruit fly, Drosophila melanogaster.
Some things that make the fruit fly a great model organism is that is small so they are easy to handle, they reproduce fast, new generations can be bred every two weeks, and they only have four chromosomes so it is easy to distinguish between them. (Reece et al., 2008) There are only four stages in the life-cycle of Drosophila melanogaster, egg, larva, pupa, and adult. Once the egg is laid it only takes a day for it to hatch. This the larva stage, during this stage the larva molts two times.The time periods between moltings are when the larva are considered an instar. On the last instar, the larva goes into the next stage which is pupa.
The moting hardens and darkens creating the puparium. One metamorphosis happens within the puparium the adult Drosophila emerges. Overall, the life cycle of the fruit fly takes two weeks, which is one of the reason why Drosophila melanogaster is a great model organism. ( Flagg, ) Thomas Hunt Morgan was an embryologist at Columbia University who used the Drosophila melanogaster for his experiments to show evidence of mendelian genetics in the 20th century.
He began mating the fruit flies and looking at many of the offspring under a microscope. It wasn’t until two years into his experiment that he found a mutant. His first mutant of Drosophila melanogaster was a white eye. The white eye mutant was different than the usual fly which had red eyes, this fly was called the wild type. Once Morgan had the mutant fly, which was male, he bred it to a female wild type. All of the offspring were wild type concluding the gene for red eyes is dominant.
When that generation was bred with each other, all the females were wild type and half of the males were wild type and the other half had white eyes. Because only the males had white eyes, this led Morgan to find that some genes can be sex linked. (Reece et al., 2008) The work of Morgan had a great significance when discussing the chromosome theory. The reason for this is that his work shows that the characteristic of things are linked on genes. In this case, the gene was eye color and knowing that it is carried on the X chromosome shows us how the chromosome theory works.
This work also goes directly hand in hand with the work that Mendel did. Although Mendel did not have any sex linked chromosomes he was working with the work of Morgan tells us the the Mendel’s ideas of gene correlation with different characters is right. From the “father of genetics” to Thomas Morgan, genetics has been studied around the world for many generations and still today is studied. (Brooker, 2016)