Amazingly, every living life form encompasses an organic memory card that contains all required data we need to keep ourselves alive as well as our genetic material. Even though mastering all knowledge of DNA (Deoxyribonucleic Acid) will be difficult and not immediate, it is essential to know as much about this little chain. As we know more about its structure and its functions, there will be more opportunities to explore and discover about ourselves and the ever-changing world around us.
Until the year 1953, the structure and make up of DNA was well unknown, but by that year, Francis Crick and James D. Watson had discovered and described this nucleic acid (Microsoft Encarta Online Encyclopedia, 2009).
It is now known that a DNA strand is a double helix made up of the simplest elements found just about anywhere in the known universe. Each of the two helix strands is defined as RNA (Ribonucleic Acid).
The RNA molecule is made up of chemical compounds called nucleotides. This helix is made up of a sugar compound, a phosphate group, and a nitrogen group – the base. The four DNA bases are: Adenine, Guanine, Cytosine, and Thymine (Microsoft Encarta Online Encyclopedia, 2009).
The following illustration shows the diagram of a nucleic chain in DNA form as well as RNA form.
It is a critical process for organisms to have the ability to copy DNA, and interestingly enough, organisms are sophisticated enough to complete DNA replication despite the numerous particular details and techniques involved. DNA is first broken down by the center into two RNA strands by a cutting enzyme called DNA polymerase (DNA, 2009).
... combine to form a Double stranded sequence in a double helix structure. 5’TGTGCGCG 3’ 3’ ACACGCGC 5’ 3.2.2 DENATURATION: The double stranded DNA molecule ... as it is a nature of DNA strands. The DNA computer hardware and software can all be made up of bimolecular where it ... contains the genetic instruction needed to construct other cells like RNA and proteins. The complex structure of the living body ...
Another enzyme generates each of the other halves of the RNA strands, and then it bonds the old and the new RNA strands to form a new DNA molecule.
Even nature cannot approach perfection; with numerous duplications in the body every second, changes in the DNA sequence are often frequent. These mutations happen when a cell divides, during replication of DNA. Mutations occur due to the following factors:
1. DNA fails to copy accurately. Most of the mutations that we think matter to
evolution are happen naturally. For example, when cells divide, they make copies
of their DNA, but sometimes the copies are not always perfect
2. External influences can create mutations. Mutations can also be caused by
exposure to specific chemicals or radiation. These agents cause the DNA to break
down. This is not necessarily unnatural — even in the most isolated and pristine
environments, DNA breaks down. Nevertheless, when the cell repairs the DNA, it
might not do a perfect job of the repair. So the cell would end up with DNA
slightly different than the original DNA and hence, a mutation.
Most of the mutations that take place in the process of DNA replication have no effect at all, and they are eventually corrected by the cell’s proofreading system. Presently, mutations are known as the mechanism in which nature selects the best fit organisms that are able to survive in the ever-changing environment. Mutations fall into several categories including:
1. Substitution – A substitution is a mutation that exchanges one base for another.
Such a substitution could change a codon to one that encodes a different amino
acid and cause a small change in the protein produced. It could also change a
codon to one that encodes the same amino acid and causes no change in the protein
Cells are the basic living units of all plants and animals. The cell is the structural and functional unit of all living organisms. There are a wide variety of cell types, such as nerve, muscle, bone, fat, and blood cells. Each cell type has many characteristics, which are important to the normal function of the body as a whole. One of the important reasons for maintaining hemostasis is to keep ...
produced. These are called silent mutations. Substitution can also change an
amino-acid-coding codon to a single stop codon and cause an incomplete protein.
This can have serious effects since the incomplete protein probably won’t function.
2. Insertion – Insertions are mutations in which extra base pairs are inserted into a new
place in the DNA.
3. Deletion – Deletions are mutations in which a section of DNA is lost, or deleted.
4. Frameshift – Since protein-coding DNA is divided into codons three bases long,
insertions and deletions can alter a gene so that its message is no longer correctly
parsed. These changes are called frameshifts. For example, consider the sentence,
“The fat cat sat.” Each word represents a codon. If we delete the first letter and
parse the sentence in the same way, it doesn’t make sense. In frameshifts, a similar
error occurs at the DNA level, causing the codons to be parsed incorrectly. This
usually generates truncated proteins that are as useless as “hef atc ats at” is
uninformative. There are other types of mutations as well, but this short list should
give you an idea of the possibilities.
(Tracking SARS Back to its Forms, 2009)
Mutations can be beneficial as well as harmful, and this is the main idea behind the reason that nature is not perfect; without perfection, there is the ability to change towards being flawless.
As life continues to evolve, it can only count on the abilities of DNA. DNA is a nanoscopic memory card holding every bit of information since the beginning of its existence. DNA is made up of simple element compounds, and it is arranged into chromosomes which make up our genes. These genes pass encoded information from generation to generation by continuous replication, and even though there are minor errors during the copying process, living organisms can always manage to avoid permanent mutations that could cause devastation or even self-destruction. This is vital to ensure the survival of a species and its ability to evolve as its environment demands.
Student Exploration: DNA Fingerprint Analysis Vocabulary: codon, DNA, DNA fingerprint, genotype, identical twins, nitrogenous base, phenotype, trait Prior Knowledge Questions (Do these BEFORE using the Gizmo. ) 1. The two navy officers shown at left are identical twins. Why do you think identical twins look so similar? Identical twins look so similar because identical twins have the same genetic ...
Deoxyribonucleic Acid. Microsoft Encarta Online Encyclopedia. (2009).
11, 2009, from
Retrieved May 14, 2009, from
DNA polymerase. (2009).
Encyclopeaedia Britannica. Retrieved May 16, 2009, from
Francis Crick. (2009).Microsoft Encarta Online Encyclopedia. Retrieved May 11,
Tracking SARS back to its source. (2009).
Understanding Evolution. University of
California Museum of Paleontology. Retrieved 17 May 2009, from
Understanding Evolution. (2009).
University of California Museum of Paleontology.
Retrieved 17 May 2009, from