The genetic information of an organism allows for the continuation of life. This genetic information is passed from parent to offspring via the molecule deoxyribonucleic acid (DNA). The structure of the DNA molecule provides a solution for the replication of the existing DNA molecule and furthermore the transmission of heritable information to the next generation. The scope of this essay will discuss how the molecular structure of DNA allows for DNA to replicate and transmit heritable information from one generation to the next.
In 1958 Frank Stahl and Matthew Meselson discovered the complementary base pairing between DNA strands and that the process of DNA replication is semi-conservative. This discovery introduced a molecular solution to how an organism’s genetic material can direct its own replication (Cooper et al., 2007.) Their model for the DNA consisted of a pair of templates, every one of which is complementary to one another. This model showed how replication is a process whereby the double helix unwinds and each strand acts as a complementary template for two new double helices to form (Campbell and Reece, 2013.) The template strands are completely complementary to one another and the two succeeding DNA molecules are identical to the original double helix; therefore making DNA an ideal structure for transferal of information from one generation to the next (Campbell and Reece, 2013).
A DNA molecule is found in the nucleus and is made up of a chain of nucleotides. A nucleotide is a nitrogenous base bonded to a pentose sugar, which is then bonded to a phosphate group (Campbell and Reece, 2013). DNA is also double stranded, which means that each whole DNA molecule has two single chains of nucleotides that act together. T...
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... and Reece, 2013). The helix can thus be said to protect the genetic code from falling apart, thereby protecting the role of DNA as the molecular basis of inheritance. The sugar phosphate backbone plays an important role in preserving the genetic code. The backbone contains strong, covalent bonds and is on the outside of the helix. This is as a result of the phosphate group of the nucleotide being slightly more positive than the nitrogenous base (Campbell and Reece, 2013). The strong sugar-phosphate backbone of DNA gives stability to the double helix and ensures that the DNA molecule, at any point in the process of replication, will not deteriorate. The sugar-phosphate backbone illustrates the relationship between DNA structure and function as it is a prime example of the structure of DNA ensuring the success of the transferral of hereditary information.
DNA is made up of nucleotides, and a strand of DNA is known as a polynucleotide. A nucleotide is made up of three parts: A phosphate (phosphoric acid), a sugar (Deoxyribose in the case of DNA), and an organic nitrogenous base2 of which there are four. The four bases are as followed: Adenine (A), Cytosine
The molecule consisted of a double helix with phosphates, deoxyribose sugar molecules, and nitrogenous bases. If the spirals were split, the DNA could replicate, which explained why genes were transferred from parents to their children. Additionally, the order of compounds on the DNA indicated that there was a unique ‘code’ on each strand. Watson and Crick believed that this ‘code’ was translated into specific proteins. , ,
The study of nucleic acids has now become a fruitful and dynamic scientific enterprise. Nucleic acids are of unique importance in biological systems. Genes are made up of deoxyribonucleic acid or DNA, and each gene is a linear segment, or polymer, of a long DNA molecule. A DNA polymer, or DNA oligonucleotide, contains a linear arrangement of subunits called nucleotides. There are four types of nucleotides. Each nucleotide has three components; a phosphate group, a sugar and a base that contains nitrogen within its structure. The sugar moiety in DNA oligonucleotides is always dexoyribose, and there are four alternative bases: adenine (A), thymine (T), guanine (G), and cytosine (C). The phosphate groups and the deoxyribose sugars form the backbone of each DNA stand. The bases are joined to the deoxyribose sugar and stick out to the side. Both oligomers, DNA and RNA, consist of 5’->3’ phosphodiester-linked nucleotide units that are composed of a 2’-deoxy-D-ribose (DNA) or D-ribose (RNA) in their furanose forms and a heteroaromatic nucleobase (A, T, G, and C; A, U, G, C), and the resulting oligonucleotide chain is composed of a polar, negatively charged sugar-phosphate backbone and an array of hydrophobic nucleobases. The amphiphilic nature of these polymers dictates the assembly and maintenance of secondary and tertiary structures the oligonucleotides can form. In the DNA duplex structure, genetic information is stored as a linear nucleotide code. This code can be accessed and replicated. RNA, or ribonucleic acid, is another structurally related essential biopolymer. RNA differs from DNA in having the sugar ribose in place of the deoxyribos...
In April of 1953, James Watson and Francis Crick published a game changing paper. It would blow the mind of the scientific community and reshape the entire landscape of science. DNA, fully knows as Deoxyribonucleic Acid is the molecule that all genes are made of. Though it is a relatively new term with regard to the age of science, the story of DNA and the path to its discovery covers a much broader timeframe and had many more contributors than James Watson and Francis Crick. After reading the paper the audience should have a better understanding of what DNA is, the most important experiments that contributed to its ultimate discovery and the names and contributions of the lesser-known scientists that helped Watson and Crick turn their idea
Deoxyribo Nucleic Acid (DNA) is a chromosome found in the nucleus of a cell, which is a double-stranded helix (similar to a twisted ladder). DNA is made up of four bases called adenine (A), thymine (T), guanine (G), and cytosine (C), that is always based in pairs of A with T and G with C. The four bases of A, C, G, and T were discovered by Phoebus Levene in 1929, which linked it to the string of nucleotide units through phosphate-sugar-base (groups). As mention in Ananya Mandal research paper, Levene thought the chain connection with the bases is repeated in a fix order that make up the DNA molecu...
The first and primary contribution to solving the DNA structure was the relationship of Crick and Watson. Without their teamwork and determination, another scientist would have discovered the structure before them. One of Crick’s bigger contributions was discovering the gene is self-replicating. After talking with John Griffith, Crick came up with the idea that the gene is self-replicating, meaning the gene has the ability “to be exactly copied when the chromosome number doubles during cell division”(126). With further discussion with Griffith, Francis believed that DNA replication involved specific attractive forces between the flat surfaces of the bases (128). One of Watson’s major contributions was after seeing the B form of DNA by Franklin, Watson knew that the structure of DNA was two-chained and that led to the building of the model of DNA (171). Also through research, Watson became aware that adenine and thymine pair together and are held by two hydrogen bonds that were identical in shape to the guanine and cytosine pair held together by at least two hydrogen bonds (194). This discovery showed that the two chains of DNA are complementary to each other. With these individual contributions coming together, Watson and Crick successfully were able to piece together the structure of DNA.
First, an initiator protein unwinds a short amount of the double helix. After this, the protein known as helicase, attaches to and then breaks up the hydrogen bonds between the bases of the DNA strands, therefore pulling them apart. As the helicase moves along the DNA molecule, it continues breaking the hydrogen bonds and also separating the two polynucleotide chains.
1. DNA replication is vital in the survival of species as through replication, identical copies of genes can be made, ensuring it is able to repair itself when it is damaged (through the process of mitosis).
Introduction DNA is the molecule that is responsible for the storing and replicating of genetic material for an organism. The genetic material is the thing that gives an organism its identity. DNA is in the shape of a double helix. It consists of a phosphate group, deoxyribose, and a nitrogenous base. The phosphate groups are synthesised together to create an ester.
For this process to begin, the genome of the strand of DNA must form a specific pattern. If a line was draw down the very center of the DNA sequence, every base of the same distance away from the center line must be matching based pairs. To illustrate this concept, a diagram bound to the same rule with ten base pairs would have matching base pairs at numbers 5 and 6, 4 and 7, 3 and 8, 2 and 9, and 1 and 10.
With the knowledge of J.M. Gulland and D. O. Jordan’s papers on acid base titrations of DNA, Watson knew that bases form hydrogen bonds to other hydrogens, and that these bonds were present in DNA (183). Watson then thought that DNA had 2 chains with identical base sequences held together with hydrogen bonds, but struggled with figuring out if replication would work perfectly indefinitely, as the wrong bases could bind together (184-188). However, this model was soon found to be incorrect, as thymine and guanine were in enol form in Watson’s model, but should have actually been in keto form (190). Then, with this error found, Watson began rearranging the bases within DNA to see if there were any formations that would not disrupt the structure of the polynucleotide chains as previous models had. After rearranging the bases, Watson discovered that A+T pairs with 2 hydrogen bonds and C+G pairs with at least 2 hydrogen bonds were the same shape, and thus did not bend the chains in a way that was not mathematically possible.
The sides of the twisted ladder are made up of alternating units of deoxyribose and phosphate. The rungs of the ladder are composed of paired nitrogen bases. Adenine always pairs with thymine, and guanine always pairs cytosine. The bases are held together by hydrogen bonds. Watson and Crick's model also suggested a way in which DNA could make copies of itself.
"The discovery of the structure by Crick and Watson, with all its biological implications, has been one of the major scientific events of this century." (Bragg, The Double Helix, p1) In the story of The Double Helix, James Watson tells of the road that led to the discovery of life's basic building block-DNA. This autobiography gives insight into science and the workings within a professional research laboratory that few members of society will ever be able to experience. It also gives the reader an idea of the reality of life for one scientist and how he struggled with the problem of DNA. However, the author's style is marked by his lack of objectivity and inclusion of many biased opinions and personal prejudices.
Who Controls Your DNA? Ever wondered what DNA is or who controls your DNA? Well, for one thing it’s not something that you could eat or wear. DNA is made up of molecules called nucleotides that contain a phosphate group, a sugar group and a nitrogen base. There are 4 types of nitrogen base and they are adenine, thymine, guanine and cytosine.
DNA (deoxyribonucleic acid) is a self-replicating molecule or material present in nearly all living organisms as the main constituent in chromosomes. It encodes the genetic instructions used in the development and functioning of all known living organisms and many viruses. Simply put, DNA contains the instructions needed for an organism to develop, survive and reproduce. The discovery and use of DNA has seen many changes and made great progress over many years. James Watson was a pioneer molecular biologist who is credited, along with Francis Crick and Maurice Wilkins, with discovering the double helix structure of the DNA molecule. The three won the Nobel Prize in Medicine in 1962 for their work (Bagley, 2013). Scientist use the term “double helix” to describe DNA’s winding, two-stranded chemical structure. This shape looks much like a twisted ladder and gives the DNA the power to pass along biological instructions with great precision.