Introduction to nucleic acids and their structure link. Mar 24, 2015 their creation is a continuous process, and a single protein chain can have 1015 amino acids added to it per second via the process outline above. Deoxyribonucleic acid or dna is a molecule that contains the instructions an organism needs to develop, live and. The structure of dna is a double helix structure because it looks like a twisted ladder. Dna structure dna is composed of polynucleotide chains the most important feature of dna is that it is usually composed of two polynucleotide chainstwisted around each other in the form of a double helix figure 61. Deoxyribose is a modified form of another sugar called ribose. Watson and crick, building on the work of chargaff, franklin and gosling, and wilkins, proposed the double helix model and base pairing for dna structure. Pauling had earlier discovered the structure of protein. Tunable dna cleavage by intercalating peptidoconjugates. This animation explores the chemical components and bonds of the nucleotides that make up dna. The subtle structural difference between the sugars gives dna added stability, making dna more. The threedimensional structure of dna the double helixarises from the chemical and structural features of its two polynucleotide chains. Introduction to dna structure duke computer science.
Its orientation, width, width between nucleotides, length and number of nucleotides per helical turn is constant. They determine that dna is a double helix structure the two dna strands 5,6 are spirally attached to each other and on the base of the nucleotide hydrogen bond is the bond which holds the structure of the. It does this by splitting apart the two strands that form the double helix. This is a comparison of the differences between dna. James watson was a molecular biologist with expertise in phage genetics. A nucleotide is composed of a phosphate group, a deoyribose sugar, and a nitrogen base. The nucleotides are linked in a directional manner via phosphodiester bonds between their sugars. Crow geneticist, university of wisconsin provides additional insights on the search for dna s chemical structure in an article. The structural stability of the dna double helix sciencing. Dna stands for deoxyribonucleic acid, while rna is ribonucleic acid. Human dna consists of about 3 billion bases, and more than 99 percent of those bases are the same in all people. Chemical structure of dna, with colored label identifying the four bases as well as the phosphate and deoxyribose components of the backbone.
Rna only has one strand, but like dna, is made up of nucleotides. D dna and e dna lack guanine in their base composition and they have 8. Importance of dna rna 3d structure nucleic acids are essential materials found in all living organisms. Im going to give you the structure of that first, because you will need it later anyway. The structure of dna was described in 1953, leading to further understanding of dna. Under the conditions found in cells, dna adopts a double helix structure. Its orientation, width, width between nucleotides, length and number of nucleotides per helical turn is. Dna, polynucleotides, nucleotides, the corresponding bases including uracil and two halogensubstituted nucleotides. However, the structure and properties of dna assembled nanoparticles are labile and sensitive to interactions with counterions, which vary with processing and application environment. The discovery that dna is the prime genetic molecule, carrying all the hereditary information within chromosomes, immediately focused attention on its structure. Im gonna write the different parts of the word in different colors. The structure of dna 14 was first discovered by james watson and francis crick in 1953.
Structure and chemical composition of nucleic acid dna. Two pyrimidines thymie and cytosine and two purines adenine and guanine. It is now recognized that besides double helical structure, dna also exists in certain unusual structures. Structure, function, packaging and properties with.
Structure of dna an introduction to genetic analysis ncbi. Ddna and edna lack guanine in their base composition and they have 8. Two of the bases, adenine and guanine, have a doublering structure characteristic of a type of chemical called a purine. As the purpose of this post was primarily to examine the chemical structure of dna. Discovery of the structure of dna article khan academy. Dna deoxyribonucleic acid is composed of two polynucleotide strands the polymers of nucleotides, which form what looks like a ladder. Science high school biology molecular genetics dna structure and replication. Rna is typically single stranded and is made of ribonucleotides that are linked by phosphodiester bonds. From franklin and gosling, 1953a, b and e number of location of nucleotides degree of repeat distance first equatorial water within unit orientation along fiber axis spacing content cell structure. Definition, structure, and discovery 1 deoxyribonucleic aci d or dna i s a mol ecul e t hat cont ai ns t he i nst ruct i ons an organism needs to devel op, l i ve and reproduce. Its base pairs are tilted relative to the axis of the helix. From franklin and gosling, 1953a, b and e number of location of nucleotides degree of repeat distance first equatorial water within unit orientation along fiber axis spacing content cell structure a crystalline 28 a 18 a 30% 2224.
Nucleic acid, naturally occurring chemical compound that is capable of being broken down to yield phosphoric acid, sugars, and organic bases. Their creation is a continuous process, and a single protein chain can have 1015 amino acids added to it per second via the process outline above. Chemical structure of dna varsha butola 1, revathi b 2, anila g 3 and sravan kumar p 4. Their main function is to maintain and transmit the genetic code. The structure of dna is dynamic along its length, being capable of. Definition, structure, and discovery1 cornell ccmr. However, it is quite common for a single rna strand to fold on itself and to form complex 3d structures, with some helical character. Dna is composed of two complementary strands oriented antiparallel to each other with the phosphodiester backbones on the exterior of the molecule. This information is stored in the form of long polymer chains. Describe chemical composition of the cell membrane. Dna assembly of nanoparticles is a powerful approach to control their properties and prototype new materials.
Although the information they carry is onedimensional, it is essential to understand the 3d structure. Several aromatic and saturated nitrogen containing molecules are also studied. Other scientists were also actively exploring this field during the mid20th century. Elucidation of the structure of dna caused a lot of excitement in genetics and in all areas of biology for two basic reasons.
The double helix structure of a dna molecule was later discovered through the experimental data by james watson and francis crick. Watson and francis crick and the race for the human genome. Overview of dna bases, complementary base pairing, and the structure. Dna is a long polymer made from repeating units called nucleotides, each of which is usually symbolized by a single letter. Became fascinated with molecular structure of dna after hearing wilkins talk at a naples conference about dna and xray crystallography photographs of dna. Let us take a look at the fascinating nucleic acid structure. The genetic code is the sequence of bases on one of the strands. Rna sometimes forms a secondary double helix structure, but only intermittently. Nucleic acid, naturally occurring chemical compound that is capable of being broken down to yield phosphoric acid, sugars, and a mixture of organic bases purines and pyrimidines. This page, looking at the structure of dna, is the first in a sequence of pages leading on to how dna replicates makes copies of itself, and then to how information stored in dna is used to make protein. Sugar and phosphate form the backbone of the dna molecule and the bases project inside. Nitrogen chemical structure in dna and related molecules by xray absorption spectroscopy sudipa mitra kirtley a,b oliver c.
The nature of dna modern genetic analysis ncbi bookshelf. The 5 and 3 positions are used to show the orientation, or directi on, of a dna strand. Watson and crick were bubbling at the fact that they had another chance to find out the structure of dna photograph of the double helix was shown to watson by wilkins. When that is the case, the 3d structure is often stabilised by the same watsoncrick basepairing as in dna. Except for some viruses, lifes genetic code is written in the dna molecule aka deoxyribonucleic acid. Near the middle of the horizontal line is c 3 phosphate linkage while at the other end of the line is c 5 phosphate linkage fig. With the 50th aniversary of the discovery of the dna structure by james. Nitrogen chemical structure in dna and related molecules by x. Dna was first recognized and identified by the swiss biologist, johannes friedrich miescher in 1869 during his research on white blood cells. Pdf the proposal of a doublehelical structure for dna over 60 years ago provided an. The 5 and 3 positions are used to show the orientation, or directi on, of a dna. In 1952, american scientist linus pauling 19011994 was the worlds leading structural chemist and oddson favorite to solve the structure of dna. C and t contain only one ring see the chemical structures in figure.
All of these features were described by watson and crick. Although the information they carry is onedimensional, it is essential to understand the 3d structure of nucleic. The structure of dna was described in 1953, leading to further understanding of dna replication and hereditary control of cellular activities. As shown in the animation, dna is a polymer of units called nucleotides, which contain deoxyribose. Nitrogen chemical structure in dna and related molecules. Although several variations on this double helix structure exist, all of them have the same basic twistedladder shape. Adenine is always opposite thymine, and cytosine is always oppostie guanine. Proteins within a cell have many functions, including building cellular structures and serving as enzyme catalysts for cellular chemical. Crow geneticist, university of wisconsin provides additional insights on the search for dna s chemical structure in an article, was there life before 1953.
The full name of dna, deoxyribonucleic acid, gives you the name of the sugar present deoxyribose. The horizontal line indicates the carbon chain of sugar with base attached to c 1. The information in dna is stored as a code made up of four chemical bases. Although dna and rna both carry genetic information, there are quite a few differences between them. Pdf structure and chemical composition of nucleic acid dna. It codes genetic information for the transmission of inherited traits. The sugarphosphate backbones of the dna strands make up the outside of the helix, while the nitrogenous bases are found on the inside and form hydrogenbonded pairs that hold the dna. As we shall see in this chapter, there are in fact variations on common themes of structure that arise from the unique physical, chemical. The structure of dna, as represented in watson and cricks model, is a doublestranded, antiparallel, righthanded helix. An enzyme, rna polymerase, transcribes dna into mrna messenger ribonucleic acid.
First, the structure suggests an obvious way in which the molecule can be duplicated, or replicated, inasmuch as each base can specify its complementary base by hydrogen bonding. Dna is a double helix, while rna is a single helix. Jan 24, 2006 structure of the catalytic region of dna ligase iv in complex with an artemis fragment sheds light on doublestrand break repair. To evaluate the genetic structure of commonly cultivated cannabis, we genotyped 81 marijuana and 43 hemp samples using genotypingbysequencing gbs. A ribonucleotide in the rna chain contains ribose the pentose sugar, one of the four nitrogenous bases a, u, g, and c, and a phosphate group. The structure of dna is dynamic along its length, being capable of coiling into tight loops and other shapes. Different wavelengths are preferentially absorbed by the backbone phos. This is the chemical structure of a deoxyribose sugar. From the perspective of design, there is no human language that can match the simplicity and elegance of dna. As shown in the animation, dna is a polymer of units called nucleotides, which contain deoxyribose sugars and nitrogenous bases.
The sugarphosphate backbones of the dna strands make up the outside of the helix, while the nitrogenous bases are found on the inside and form hydrogenbonded pairs that hold the dna strands together. Dna dna deoxyribonucleic acid dna is the genetic material of all living cells and of many viruses. Nucleic acids are the main informationcarrying molecules of the cell and play a central role in determining the inherited characteristics of every living thing. Mitochondria are structures within cells that convert the energy from food into a form that cells can use. Chapter 2 structures of nucleic acids nucleic acids. As the purpose of this post was primarily to examine the chemical structure of dna, the discussion of replication and protein synthesis has been kept brief and relatively simplistic. Molecular biology and applied genetics 1 chapter one the cell specific learning objectives. Let us make an indepth study of the deoxyribonucleic acid.
Study of all these molecules allows a variety of chemical effects to be investigated. The processes ofdna replication, recombination and transcription all require dna rotation, and during dna synthesis the rotation speed approaches 6000rpm. Engineering the structure and properties of dnananoparticle. Indeed, there is no one generic structure for dna and rna. A gene is a specific sequence of bases which has the information for a particular protein.
Because these two chains are held together by hydrogen. The sides of the ladder are made of alternating sugar deoxyribose and phosphate molecules while the steps of the ladder are made up of a pair of nitrogen bases. Dna deoxyribonucleic acid is also known as the basic unit of nucleus which is present inside the cell. Here we show that substituting polyamines in place of elemental counterions significantly enhanced the. Pdf the proposal of a doublehelical structure for dna over 60 years ago provided an eminently satisfying explanation for the heritability of genetic. The helical structure of dna is variable and depends on the sequence as well as the environment. A, b and z dna helix families david w ussery,danish technical university, lyngby, denmark there are three major families of dna helices. What i want to do in this video is dig a little bit deeper. As we shall see in this chapter, there are in fact variations on common themes of structure that arise from the unique physical, chemical, and topological properties of the. Introduction pictures of the double helix of deoxyribonucleic acid. Voiceover we already have an overview video of dna and i encourage you to watch that first. Both have sets of nucleotides that contain genetic information. The structure and function of dna molecular biology of.