Amazing find on old hard drive part 1

While finding a hard drive to bring to work, I found some of my old undergraduate work. I have decided to post some of my papers in my blog.

Here is part 1:

Abstract:

Throughout this paper, the works of Gregor Mendel and Thomas Morgan will be talked about.  Mendel was considered the first person ever to have worked with genetic research.  He worked with pea plants, but he never even knew what he was really dealing with.  Mendel used pea plants because all he was really trying to do was bred the best pea plants for the monastery where he lived.  Almost one hundred years later, Thomas Morgan set out trying to prove that the laws and theories Mendel set were completely wrong.  All Morgan’s work showed that Mendel was more right now than ever.

This paper will go back and show people some of the many experiments done by Gregor Mendel and what the results mean to us today.  Also it will show how the work of Thomas Morgan showed that Mendel’s work was almost flawless.  Later the results will be shown.  The results of Mendel and Morgan will  be compared and contrasted.  Also in the discussion, the work of Mendel will be brought into the light of today and will pave the way for all the genetic research we now hold dear.  In the end, cloning will be discussed and how Mendel’s work helped scientists are looking and cells and chromosomes today.

Introduction:

“You have your father’s eyes.”  This phrase, or something like it, is known by most people.  It does not mean that one literally has their father’s eyes, but their eyes are similar to one of their parents.  All of one’s traits are linked to their parents.  This is due to the fact that every chromosome within one’s body is from either one of the parents.  One gets half of their chromosomes from one parent and the other half from the other parent.  Everything that has to with inheritance from genes from parents to their offspring can all be explained by the works of Gregor Mendel and those who follows in his footsteps to broaden his findings.

For many centuries nobody even knew about DNA let alone chromosomes.  Gregor Mendel, “the father of genetics”, had no that all his experiments dealt with chromosomes.  From all of his experiments, Mendel was able to create three theories, two of them which became laws.  The two laws are the principle of segregation and the principle of independent assortment.  The theory he made is the law of dominance.                                              The work of Gregor Mendel was the most important work in genetics ever done even today.  This paper will deal with the three theories of Mendel and what they mean.  Also the many different experiments performed by Mendel and how those experiments developed into the field of modern genetics that are used by many scientists today.

Methods and Materials:

For all of his experiments, Mendel experimented with pea plants.  Mendel was a monk that lived in a monastery in the year 1856.  Pea plants were a good choice for Mendel’s investigations.  They are easy to grow, and they mature quickly.  Different plants show sharply contrasting traits^1.  Mendel experimented with seven pairs of contrasting traits.  These seven traits are the seed shape, the seed color, the seed coat color, the pod color, the pod shape, the stem length, and the flower position.

Mendel’s first theory he made was the principle of segregation.  The principle, or law, of segregation states that members of each pair of alleles of a gene separate when gametes are produced in meiosis^2.  Genes are units of information about specific traits, and they are passed from parents to offspring.  Each gene has a specific location on a chromosome.  Alleles are different molecular forms of a gene^1.

Mendel’s second theory was the principle of independent assortment.  This states that pairs of alleles separate independently of each other during gamete formation.  We now know that this is only true for genes located on different chromosomes^2.  This means the pairs of genes separate apart from one another during the meiosis.  In meiosis, gametes form and the chromosomes split and start to form new cells.

Mendel’s last theory is the law of dominance.  This theory is stated that each inherited characteristic is determined by the interaction of two heredity factors, one from each parent.  In the characteristics that he studied, Mendel found that one factor of the pair always predominated^1.  This means that one factor is the dominate one and will show up.  The other factor is the recessive one and it is a rare occasion when it is seen over the dominate factor.

One of the experiments with pea plants Mendel worked on was contrasting tall and short pea plants.  The parents were one tall plant and one short plant.  He crossed pollinated the parents and the first generation (f1) were all tall.  Mendel then allowed the f1 to self pollinate.  Of their offspring three-fourths were tall (787 plants) and one-fourth were short (277 plants).  Then this generation self pollinated and the hybrids from the generation produced once again three-fourths tall and one-fourth short^4.

Other traits that Mendel worked with were the seed shape being either round or wrinkled.  The seed colors could be either yellow or green.  The seed coat color was either grayish brown or white.  The pod color was either green or yellow.  The pod shape could be inflated or wrinkled.  The flowers positions could be lateral or terminal ^1.

All of Mendel’s experiments can easily be done with any trait found from any living organism when they breed.  A simple monohybrid cross is one in which data about one gene with two alleles is obtained.  A diagram called a Punnett square (named after Reginald Punnett!) can be used to predict the outcomes of such a cross^2.  The Punnett square looks like an ordinary box with the traits (or gametes) on the outside.  It is used just like a cross multiplication diagram would be used in math.  An example of what a Punnett square looks like is stated below for when a pure tall plant and a pure short plant are bred.  In order to make this work one just brings the top row letter to the rows below them.  Then bring the letter from the left column to the columns to the right of them.  Just put the capital letter, if there is one, in front of the two letters combined to designate what type of plant it will be.  TT would be a pure tall plant.  tt would be a pure short plant.  Tt would be a hybrid mix with the T gene being the dominant one while t would be the recessive gene.

Gametes	T	T
t
t

Mendel was not the only scientist that worked with chromosomes and their traits.  Thomas Morgan was not convinced that Mendel had the right explanation.  Seeking a better way to explain inheritance, he chose to work with the fruit fly.  The fruit fly has a number of advantages.  It breeds quickly and requires little food and space^5.

Morgan breed male and females flies to see what traits are carried, if any, by the male or female.  He breed a male fly, which he found by chance, that had white eyes and a female that had red eyes.  It was unusual that the male had white eyes because the fruit fly has red eyes.  The male fly happened to be a mutant.  Morgan breed them and wanted to see if the male Y chromosome had something to do with the white eyes^5.

Results:

When Mendel cross-bred the pea plants, he results were the same for every trait.  Let’s use the tall and short pea plant experiments.  The offspring of the parents were showed the dominant trait, but were hybrids because they carried within them the recessive gene.  When these hybrids were allowed to self pollinate, the offspring were 75% tall and only 25% short^1.

Mendel found out that these results were true for every trait.  When the hybrids were allows to reproduce, the offspring always showed 75% of the dominant gene and 25% of the recessive gene.  When the plants with the dominant gene were bred, some of their offspring were pure-bred tall pea plants again, while others were hybrids.  The same thing happened when the plants with the recessive genes were bred^2.  So the example from above completed would look like this.

Gametes	T	T
t	Tt	Tt
t	Tt	Tt

The work of Morgan with the fruit flies looked very similar to the results of Mendel.  It turns out when the male fly with white eyes is breed with the female with red eyes the ratio was the same as with the pea plants.  75% of the flies had red eyes and 25% had white eyes.  The Y chromosome found in the male fly carries the recessive trait for the white eyes.  Morgan’s findings confirm Mendel’s rules that say that chromosomes are the carriers of genetic traits^5.

After Mendel carried out hundreds of experiments he came up with three ideas that must be true based on his results.  One is that each parent carries two units of heredity governing each trait.  The second is when parents make their sex cells; only one unit of heredity goes into each.  The third is when the units combine in the offspring, the effect of one may dominate the effect of the other^6.

Discussion:

The work of Gregor Mendel is the most important work done in the history of genetics.  The work of Thomas Morgan proved that Mendel’s experiments and results were very accurate.  Mendel proved that chromosomes carry genetic traits that make an organism have certain qualities to it.  These traits come directly from the parents of the organism.  In some cases, the offspring of the parents will show the recessive gene, almost making it seem entirely different from the rest.

I think that more work should be done with genetics.  If Mendel was able to figure out how to make pea plants with certain traits, why can not this type of work be done with other organisms like humans? Society is already seeing this type of genetic research being done.  Cloning is one of the most significant work being done right now.  With cloning, people that need new organs or tissue can get it without a donor.  Doctors will be able to clone the person’s own organs using their cells.  Many people think that this is wrong, but this paper will not discuss the social debates about cloning and other genetic works.

Conclusion:

Gregor Mendel was one of the greatest minds that ever work with the idea of chromosomes.  He discovered, without even knowing it, that traits are carried from parents to their offspring through chromosomes.  Like many have said before he was the “father of genetics”.    Others have tried to prove his theories wrong, but in the end they only strengthen Mendel’s laws.  One day if scientists keep using his theories and following his work, we may one day be able to make a human being with certain traits in them.

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