Molecular Biology

Why Dna is the Molecule Responsible for Inheritable Traits

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Throughout history, many a scientist has studied a chemical substance that duplicated itself. Eventually, scientists learned that this substance, housed within each gene, was deoxyribonucleic acid (DNA) and that it carried the road map to one's life; that is, it transferred genetic information from the parents to the offspring and determined who they were. In fact, according to Csiro's Double Helix science club (2006), "A person has about 9 million kilometers of DNA. That's enough to reach to the moon and back 13 times!" Therefore, it is important to know that DNA and its' role of replicating, repairing, and transmitting genetic information to the cells of the body preserves and continues the life cycle.

DNA History

In the 1860's, Johann Friedrich Miescher, a Swiss physiologist, was studying the chemistry of leukocytes, which are the white blood cells. Dr. Miescher began gathering pus specimens from the bandages off from soldiers during the Crimean War. While his passion was to study the chemical composition, the structure, and the properties of the nucleus, he continued his studies with leukocytes and made an extraordinary discovery. In 1869, Johann Friedrich Miescher was able to isolate the nuclei and identify a chemical make-up of sulfur, phosphorous, and nitrogen; Miescher called this nuclein (University of California, Los Angeles, 2002.), which is now known as DNA. Later, through further analysis, Miescher was able to separate the nuclein into an acid and protein and the substance then became known as nucleic acid. Years later, in the 1890's, a German physiologist named Albrecht Kossel discovered the nucleic acid basis of cytosine, adenine, thymine, guanine, and uracil. In 1944, three biologists, Avery, MacLeod, and McCarty, were studying bacteria and the properties which allowed one strain to transform. The trio discovered deoxyribonucleic acid and gave it its' name. Then in 1952, amidst the famous Hershey and Chase experiments in viruses, Hershey and Chase discover that the viruses replicate and conclude that DNA was involved in the replication (Clinton Community College, n.d.). Thus, DNA became known as a genetic material.

DNA Structure

In 1953, scientists James Watson and Francis Crick discovered the double helical shape of DNA. The double helix was made up of two strands of nucleotides, complimentary base pairs that formed the rungs of the double helix, and the backbone of the double helix formed by the bonding of the sugars and phosphates. The four main nitrogenous basis are cytosine, adenosine, guanine, and thymine. It was found that adenosine bonded with thymine and cytosine bonded with guanine; these bonds were formed with hydrogen.

DNA Functions

Deoxyribonucleic acid employs many functions. While DNA acts as the architect, its' components perform the architecture. An essential function of DNA is the process of replication, in which a strand of DNA duplicates itself. During this process, DNA helicase unzips the double helix and separates the two DNA strands. Simultaneously, the complimentary base pairs are separated as the hydrogen bonds break. The DNA polymerase then acts as a photocopier, uses the nucleotide formation of the original strand of DNA, and produces a new strand of DNA. Occasionally, throughout the process of replication a strand of DNA becomes altered, this is called mutation. Some mutations can be repaired by DNA ligase and some cannot. Some examples of irreparable mutations are forms of cancer; according to (2006), two examples of inherited mutations are "retinoblastoma, which is a mutation in chromosome 13, and Wilm's tumor, which is a mutation in chromosome 11." As deoxyribonucleic acid contains the information that is necessary for the body to function, it also carries this instruction manual to the new cells. In the same respect, if a mutation takes place, the mutation will continue to pass on to the new cells until it is repaired. As stated before, some mutations, or damaged DNA, can be repaired. This damage is located and repaired by DNA polymerase ligase proteins, as the sugar and phosphate bonds, and as the backbone of the new strand of DNA is formed.


A person's genetic inheritance can determine a person's eye color or hair color, level of immunity to sickness and/or disease, rate of growth, adaptability, and many more. The passing of DNA from the parents to the offspring plays a large role in preserving the life cycle. (With animals and plants, the passing of DNA also helps to preserve the food chain.) It is important to know that the transfer of inheritant traits begins with the genetic code. The genetic code is composed of groups of three nucleotides stranded together. Each group of three nucleotides is called a codon, which also represents an amino acid. Furthermore, each amino acid has a code name. Each code name is given and translated within a unique sequence, exclusive to the individual, and forms the genetic code (similar to a deciphered message). Ribonucleic acid (RNA) is responsible for reading the genetic code, deciphering it, and translating it to the rest of the cells in the body. That leads back to the process of replication. Replication essentially separates the two strands of a DNA molecule, and continually duplicates the DNA for the new cells. Without the process of replication the cells would die and, eventually, so would the organism. It is during the replication process that damaged cells can be assessed for repairs, and most can be repaired by the DNA ligase. Prior to cell division and before the end of replication, DNA ligase secures the backbone of the new strand of DNA by linking the sugar and phosphates of the new strand together. Synchronically, the ligase has the ability to analyze the strand of nucleotides, check for any abnormalities, and correct most of the damaged DNA molecules. Once the ligase has completed its function, two matching double helixes of DNA will be available. This process of DNA replication is constant; it enables genetic material to be transferred from the parents and to the offspring.
Without the inheritance of DNA, people are a mere darkness without a purpose or hope. If the inheritance of DNA were to halt, there may still be people on the earth, but the people would lack adaptability, survival skills, uniqueness, and individualism. Eventually, the people could become extinct. Therefore, it is important to know that DNA and its' role of replicating, repairing, and transmitting genetic information to the cells of the body preserves and continues the life cycle.

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Audesirk G., Audesirk T., & Byers B.E., (2006). Life on Earth. University of
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Clinton Community College. (n.d.). DNA: The Search to Identify the Genetic Material.
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CSIRO Education. (2006). What is DNA? Retrieved August 11, 2006 from:

GlaxoSmithKline. (2004). Kids Genetics: DNA. Retrieved from:

Lewis, S. (2005). Function of DNA. Retrieved from: function.htm.

Rockefeller University. (n.d.). When was DNA Proved to be the Chemical Basis of
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University of California, Los Angeles. (2002). Can Matter Store Active Information?
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More about this author: Celestia Canute

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