Unraveling the mystery of DNA - Essay Example

The gene is the unit of Life. The soul is the unit of Humanity. We know the alphabet of Life, we have unravelled the But remember, like words, DNA has significance beyond the sum of its parts David Bromfield. Whenever we think of the word DNA our mind wanders to scientists frowning at a microscope and the likes of the cast of "X-files" or some team in the Discovery channel launching a Criminal investigation. Interestingly the concept of DNA analysis has helped many fields of criminal investigation and genetic engineering. The "chemistry" of the "DNA" has become an integral part of biology and physics and there is no doubt that science fiction movies depicting human clones will become a reality some day(although in a less Melodramatic way). The most popular image of the DNA looks something like this DNA has been defined as The long, spiralling molecule that orchestrates the cell's daily operations and provides the genetic blueprint for the physical characteristics of all living organisms. When made up of two strands, the strands intertwine like a spiral staircase to form a structure called a double helix. Subunits, called bases, are the rungs of the staircase.1 This Image is actually the brain child of two scientists as illustrated by the 2"Double Helix" model .It was discovered and endorsed by Watson and Crick in the late 1950's as having the closest resemblance to the structure for DNA.3 Academic opinion has endorsed this structure as highly accurate as well.The diagram shows the two strands of DNA intertwined in a right handed helix and a two fold axis in its symmetry .Other salient features of the Helix diagram are that the sugar-phosphate backbone will be external to the structure and the phosphate groups(see below) will be giving a high,uniform charge.4The bases in the model will be perpendicular to the axis of symmetry and the purine and pyrimidine rings are spaced 0.34 nm apart with intermolecular base-pairs in the center. The reason that the bases have to be stacked on top of each other is to provide stability to the structure.5 The double helix has its strands connected by H-bonds susceptible to damage by heat, acidic or basic conditions.6The damage can separate the DNA (denaturation) although DNA containing a higher proportion of GC will probably be more stable and with the recurring sequence of "AT" will be least stable.How then can this DNA be repaired In this regard it can be said that One Strand DNA repair will allow a damaged or missing base to use the information on the other side to regain the lost data which is duplicated by the data contained in the opposite strand base. How is the DNA structured Deoxyribonucleic acid or DNA is a part of our body which contains our genetic origins and functions which will determine how different or how similar we will look like our ancestors based on the genetic information stored in this cell. An embryo/or living organism will grow based on the instructions contained in the DNA which will later determine our skin and hair pigmentation, special body traits and even psychological attitudes. A closer look at the DNA cell it is a long, but narrow string-like object. It is often described with the following attributes i.e. " A one foot long string or strand of DNA is normally packed into a space roughly equal to a cube 1/millionth of an inch on a side. This is possible only because DNA is a very thin string."7 There will be varying types of information which can be stored by the DNA and build for the development of other cells.8This will include the coding sequences for RNA and protein muscles, identifiers for groups of coding sequences expressed coordinately or sequentially,sites for initiating and terminating transcription of DNA into RNA,signals for processing primary transcripts to smaller functional RNAs,control sequences setting the appropriate level of expression under specific conditions,sequence determinants making domains for chromatin condensation and chromatin remodelling,binding sites affecting spatial organisation of the genome in the nucleus or nucleoid,sites for covalent modification of the DNA (such methylation),control sequences for initiating DNA replication,sequence structures permitting complete replication at the ends of linear DNA molecules(telomeres),centromeres and partitioning sites for equal distribution of duplicated DNA molecules to daughter cells following cell division ,signals for error correction and damage repair, as well as sites for genome reorganization (DNA rearrangements).9 This diagram above show how the DNA molecule is structured. Notice how the deoxyribose sugar and phosphate groups of the nucleotides are grouped close vertically. It is worth nothing in this diagram and the next one how the DNA will always be contained with a paired base structure where DNA Adenine pairs with Thymine and Guanine pairs with Cytosine. 10 Source: http://www.molecularstation.com/images/chemical-structure-dna.gif This diagram above shows the chemical details of the DNA structure i.e. the elements it is composed of. Notice how the who molecule is actually a longish polymer composed of "nucleotides" connected by sugar and phosphate. In the above diagram it can be seen that the four bases lining the centre of the molecule encode information which will ultimately define how the amino acids line up within the protein structure which will then be replicated the RNA. Cytosine, Guanine, Thymine, Adenine are the building blocks which determine the order of these building blocks determining each person's characteristics.11 To put it simply the DNA is the foundation of the entire molecule structure of the molecule and every cell with contained in the body(in the person's skin, cells ,semen and saliva).Interestingly the DNA in living organisms does not exist as a singular molecule but (as apparent from its popular diagram) an intertwined strand of twin DNA molecules.This entire intertwined strand of DNA contains the historical/ancestral information is also known as the "phylogeny" of organisms. The Chemistry of the DNA and RNA As mentioned above the RNA is a chemical cousin of DNA and is responsible for translating the genetic code of DNA into proteins.12 RNA and DNA are similar structurally in many ways (they look alike) but the RNA is composed of repeating units called ribonucleotide monophosphates and the .DNA's repeating units are -deoxyribonucleotide monophosphates. Both Acids are composed of long polynucleotide chains joining different t purine or pyrimidine bases with N-glycosidic bonds.. Based on varying polarity both Acids will have different equations for example GTCA DNA sequence will become the GUCA RNA sequence causing varied information storages.In a sense the DNA acids is the original version and will be likely to remain more stable than the RNA structure.13 The 2' OH on the RNA forms 2'3'phosphodiester intermediates under basic conditions which breaks down to a mix of 2' and 3' nucleoside monophosphates. Therefore, the RNA polynucleotide is unstable.14 Practical Uses of DNA DNA has played a pivotal role in the establishment of guilt of criminals involve in rape and murder as well as establishing paternity in family and inheritance law litigation. It has also led to historical queries into the origin of blue eyes and blond hair and has helped solve the mystery with in the human evolution. Other uses have included using the Acid to catastrophe victims ,in the identification of endangered species, detection of bacteria and viruses, livestock breeding and the making of Genetically modified food. Some forensic techniques making use of DNA Restriction Fragment Length Polymorphism (RFLP) One of the pioneering techniques of forensic investigation to allow the development of newer, more efficient DNA-analysis techniques.This disadvantage is that large samples of DNA are required and the technique does not work well with DNA infested with dirt or mould. PCR Analysis, It's a useful technique which duplicates copies from a single DNA sample for study/investigation and analysis on every size of biological samples no matter how small. Again contamination can ruin the procedure and care has to be taken to preserve the samples properly. Other techniques include the STR analysis which is used to distinguish the DNA structures and it commonly employed by the Federal Bureau of Investigation (FBI) .The CODIS programme will then match the criminals/victims with one of the 13 specific STR regions for CODIS. This is a fairly reliable programme based on the fact that the odds of two individuals having the same 13-loci DNA profile is about one in a billion. The use of DNA for Cloning In 1997 when the question of human cloning rose(after the debut of the celebrity cloned sheep Dolly) there was a world wise uproar as to its scientific and ethical implications.However the step was much lauded by the science community as to the uses of the DNA.It should be borne in mind that cloning technology cannot be restricted to producing identical genetic twins of another organism and it can broadly be classified as recombinant DNA technology or DNA cloning, reproductive cloning, therapeutic cloning. However the experiment was a failure and Dolly died in 2003 after terrible bodily conditions like lung cancer and crippling arthritis.However Dolly was able to live almost a decade and have children the natural way.Dolly was a result of reproductive cloning or "somatic cell nuclear transfer" (SCNT), whereby the geneticists are able to transfer DNA l from the nucleus of a donor adult cell to an egg whose nucleus, and thus its genetic material, has been removed.This is a useful study as now the scientists are considering therapeutic cloning based on this study by cloning and organs for transplants. However modern science is still facing challenges in this field and it has been reported that such attempts have failed with in minutes of initiation.There were proposals for a while asking for the utilisation of genetically modified pigs from which organs suitable for human transplants could be transplanted.(xeno-transplantation.) Genetically modified foods and the use of DNA The concept of GM foods has faced its share of the good,bad and ugly controversy in the recent years.These foods are a result of DNA based modification where DNA is altered by genetic engineering and the concept debuted the market in the mid 90's. Foods like soybean, corn, canola cotton etc are genetically modified to increase their size and quality as well quantity.The same technique has been utilised by the livestock growers and poultry farmers.The practice has been attacked due to threat to and environmental safety and cruelty to animals.Genetically modified livestock has found its way into the markets of even the most developed countries.The facts about the large scale abuse being carried out on these farmers are very disturbing as one report reveals, "Millions of broiler chickens are housed in industrial barns containing up to 25,000 birds. Birds are bred to have such heavy breasts that many are unable to stand, and die of thirst because they are unable to reach water.".15 Conclusion This report has reviewed the structural and chemical qualities of DNA with the relevant diagrams and equations. It has also discussed the use of DNA in crime solving and medicine (cloning) as well as the use and controversy surrounding genetically modified foods. The DNA remains a mystery to us despite the large amount of research that has been carried out in it during the past many decades and it is worth looking forward to what the future holds for the new discoveries in the field of DNA. References 1. http://www.dna.gov/basics/biology/ 2. http://www.biochem.uwo.ca/meds/medna/doublehelix.html 3. www.biotechnologyonline.gov.au 4. http://www.ornl.gov/sci/techresources/Human_Genome/elsi/forensics.shtml 5. Robert Olby 1974, The Path to the Double Helix: The Discovery of DNA,University of Washington Press 1994 Dover Publications,they 6. Genetic engineering of filamentous fungi - Progress, obstacles and future trends Biotechnology Advances,Volume 26, Issue 2,March-April 2008, Pages 177-185 Vera Meyer 7. http://www.ornl.gov/sci/techresources/Human_Genome/elsi/cloning.shtml 8. http://edition.cnn.com/interactive/health/0108/cloning.timeline/content.html 9. Wikipedia.com 10. DNA computing based RNA genetic algorithm with applications in parameter estimation of chemical engineering processes Computers & Chemical Engineering, Volume 31, Issue 12, December 2007, Pages 1602-1618 Jili Tao and Ning Wang 11. The analysis of chromatin remodeling and the staining for DNA methylation and histone acetylation do not provide definitive indicators of the developmental ability of inter-species cloned embryos,Animal Reproduction Science, Volume 105, Issues 3-4, May 2008, Pages 438-450,Eugine Lee, Ji Hye Kim, Seon Mi Park, Yeon Ik Jeong, Jong Yun Lee, Sun Woo Park, Jiho Choi, Huen Suk Kim, Yeon Woo Jeong, Sue Kim, Sang Hwan Hyun and Woo Suk Hwang 12. The impact of DNA contamination of bone samples in forensic case analysis and anthropological research Legal Medicine,Volume 10, Issue 3,May 2008, Pages 125-130 Nicole von Wurmb-Schwark, Anke Heinrich, Mechthild Freudenberg, Michael Gebhr and Thorsten Schwark 13. FaSTR DNA: A new expert system for forensic DNA analysis 14. Forensic Science International: Genetics, In Press, Corrected Proof, Available online 1 February 2008,Timothy Power, Brendan McCabe and Sally Ann Harbison 15. Trace DNA analysis: Do you know what your neighbour is doing: A multi-jurisdictional survey,Forensic Science International: Genetics, Volume 2, Issue 1, January 2008, Pages 19-28,Jennifer J. Raymond, Roland A.H. van Oorschot, Simon J. Walsh and Claude Roux Read More