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Essay on DNA Replication | Genetics

essay on dna

❶The DNA replication takes place during S sub stage of interphase.

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Understanding the Genetic Evidence
The Ancestors of the American Indians
Research Paper on DNA

Consequently, most early Latter-day Saints assumed that Near Easterners or West Asians like Jared, Lehi, Mulek, and their companions were the first or the largest or even the only groups to settle the Americas. Building upon this assumption, critics insist that the Book of Mormon does not allow for the presence of other large populations in the Americas and that, therefore, Near Eastern DNA should be easily identifiable among modern native groups.

The Book of Mormon itself, however, does not claim that the peoples it describes were either the predominant or the exclusive inhabitants of the lands they occupied.

In fact, cultural and demographic clues in its text hint at the presence of other groups. Ivins of the First Presidency cautioned: The Book of Mormon … does not tell us that there was no one here before them [the peoples it describes].

It does not tell us that people did not come after. Joseph Smith appears to have been open to the idea of migrations other than those described in the Book of Mormon, 8 and many Latter-day Saint leaders and scholars over the past century have found the Book of Mormon account to be fully consistent with the presence of other established populations. Finding and clearly identifying their DNA today may be asking more of the science of population genetics than it is capable of providing.

A brief review of the basic principles of genetics will help explain how scientists use DNA to study ancient populations. It will also highlight the difficulty of drawing conclusions about the Book of Mormon from the study of genetics. DNA—the set of instructions for building and sustaining life—is found in the nucleus of almost every human cell.

It is organized in 46 units called chromosomes—23 received from each parent. These chromosomes contain about 3. Any two individuals share approximately Genetic variations are introduced through what geneticists call random mutation. Mutations are errors that occur as DNA is copied during the formation of reproductive cells. These mutations accumulate over time as they are passed from generation to generation, resulting in unique genetic profiles.

The inheritance pattern of the first 22 pairs of chromosomes called autosomes is characterized by continuous shuffling: The 23rd pair of chromosomes determines the gender of a child XY for a male, XX for a female.

Because only males have the Y chromosome, a son inherits this chromosome mostly intact from his father. Human cells also have DNA in a series of cell components called the mitochondria. Mitochondrial DNA is relatively small—containing approximately 17, instructions—and is inherited largely intact from the mother. Mitochondrial DNA was the first type of DNA to be sequenced and was thus the first that geneticists used to study populations.

As technology has improved, analysis of autosomal DNA has allowed geneticists to conduct sophisticated studies involving combinations of multiple genetic markers. Population geneticists attempt to reconstruct the origins, migrations, and relationships of populations using modern and ancient DNA samples. Examining available data, scientists have identified combinations of mutations that are distinctive of populations in different regions of the world.

Unique mitochondrial DNA and Y-chromosome profiles are called haplogroups. At the present time, scientific consensus holds that the vast majority of Native Americans belong to sub-branches of the Y-chromosome haplogroups C and Q 14 and the mitochondrial DNA haplogroups A, B, C, D, and X, all of which appear to have come to the Americas via migrations from East Asia.

From this evidence, scientists conclude that some Europeans or West Asians migrated eastward across Asia, mixing with a group that eventually migrated to the Americas millennia before the events described in the Book of Mormon. Additional DNA markers from Europe, West Asia, and Africa exist in the DNA of modern native populations, but it is difficult to determine whether they are the result of migrations that predated Columbus, such as those described in the Book of Mormon, or whether they stem from genetic mixing that occurred after the European conquest.

Scientists do not rule out the possibility of additional, small-scale migrations to the Americas. Even if geneticists had a database of the DNA that now exists among all modern American Indian groups, it would be impossible to know exactly what to search for.

It is possible that each member of the emigrating parties described in the Book of Mormon had DNA typical of the Near East, but it is likewise possible that some of them carried DNA more typical of other regions. This phenomenon is called the founder effect. Consider the case of Dr. Perego, a Latter-day Saint population geneticist. In the case of the Book of Mormon, clear information of that kind is unavailable. The difficulties do not end with the founder effect.

Even if it were known with a high degree of certainty that the emigrants described in the Book of Mormon had what might be considered typically Near Eastern DNA, it is quite possible that their DNA markers did not survive the intervening centuries. Principles well known to scientists, including population bottleneck and genetic drift, often lead to the loss of genetic markers or make those markers nearly impossible to detect. Population bottleneck is the loss of genetic variation that occurs when a natural disaster, epidemic disease, massive war, or other calamity results in the death of a substantial part of a population.

These events may severely reduce or totally eliminate certain genetic profiles. In such cases, a population may regain genetic diversity over time through mutation, but much of the diversity that previously existed is irretrievably lost. Illustration of population bottleneck. Due to a dramatic reduction in population, some genetic profiles represented here by the yellow, orange, green, and purple circles are lost. Subsequent generations inherit only the DNA of the survivors.

In addition to the catastrophic war at the end of the Book of Mormon, the European conquest of the Americas in the 15th and 16th centuries touched off just such a cataclysmic chain of events. As a result of war and the spread of disease, many Native American groups experienced devastating population losses.

Genetic drift is the gradual loss of genetic markers in small populations due to random events. A simple illustration is often used to teach this concept:. Fill a jar with 20 marbles—10 red, 10 blue. The jar represents a population, and the marbles represent people with different genetic profiles. Draw a marble at random from this population, record its color, and place it back in the jar. Each draw represents the birth of a child.

Draw 20 times to simulate a new generation within the population. The second generation could have an equal number of each color, but more likely it will have an uneven number of the two colors. As a matter of fact it has revolutionized the way in which law enforcement officials look at evidence collection and processing.

DNA analysis has evolved from being considered a 'mad scientist' approach to evidence processing to what would now be considered a gold standard within its respective community.

DNA analysis is multifaceted in its use in that it can-not only be used for successful prosecution but can be used as a means of exoneration as well. In Damon Thibodeaux was convicted of the rape and murder of his 14 year old step-cousin, Crystal Champagne, in Westwego; several miles southwest of New Orleans. Champagne had been last seen by her family when she left to go to a nearby grocery store.

When she failed to return home, her family notified the authorities and an investigation ensued. Her body was later found under a bridge with her pants pulled down and a wire ligature wrapped around her neck. Detectives began questioning potential witnesses which included Thibodeaux.

After a lengthy interrogation, nine hours, Thibodeaux confessed to the rape and murder of Crystal Champagne.

This confession served as the proverbial nail in the coffin as it related to Thibodeaux's conviction in October of Thibodeaux unsuccessfully tried to appeal his conviction in He alleged that his confession was coerced by investigators after a lengthy and unrecorded interrogation. In , Thibodeaux's legal team, with the assistance of representatives from the Innocence Project, convinced the Jefferson Parish District Attorney's office to reinvestigate the case.

Subsequent DNA testing revealed that Thibodeaux was not the killer and that Crystal Champagne had not, in fact, been raped. After he walked out of prison, Thibodeaux said, he took the first step toward that new life, inhaling a deep breath of 'free air. Each and every human being has a specific genetic code unique to that individual.

Our genetic code or genes are made up of deoxyribonucleic acid or DNA. DNA evidence can be found in many different sources. DNA can be extracted from human hair, blood, sweat, saliva and skin cells just to name a few of its sources.

Over the course of the last few decades there have been vast technological advances in the way in which modern day law enforcement investigates crime.

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Essay # 5. Forms of DNA: Depending upon the nucleotide base per turn of the helix, pitch of the helix, tilt of the base pair and humidity of the sample, the DNA can be observed in four different forms namely, A, B, C and D.

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Composing DNA Essay should be ideally done in two stages. First and foremost is the pre writing stage, where one needs to think and collect ideas for the essay. First and foremost is the pre writing stage, where one needs to think and collect ideas for the essay. ADVERTISEMENTS: In this essay we will discuss about: 1. Definition of DNA Replication 2. Mechanism of DNA Replication 3. Evidences for Semi-Conservative DNA Replication 4. Models for Replication of Prokaryotic DNA. Essay # Definition of DNA Replication: DNA replicates by “unzipping” along the two strands, breaking the .