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If it could be possible how would DNA and RNA have to rearrange themselves? The interaction between mRNA and tRNA are illustrate in Figure \(\PageIndex{23}\). A nucleotide in an RNA chain will contain ribose (the five-carbon sugar), one of the four nitrogenous bases (A, U, G, or C), and a phosphate group. tRNA takes amino acids to rRNA, where the protein is formed. You can also search for this author in It is well know that dsDNA structure is sensitive to hydration (see section on A, B, and Z DNA). DNA bears the hereditary information thats passed on from parents to children, providing instructions for how (and when) to make the many proteins needed to build and maintain functioning cells, tissues, and organisms. The name comes from the fact that these molecules are acids that is, they are good at donating protons and accepting electron pairs in chemical reactions and the fact that they were first discovered in the nuclei of our cells. In this model, a pyrimidine strand lies in the major groove of an A-form like WatsonCrick double helix and forms Hoogsteen type . DNA structures gets obviously more complicated as it packs into the nucleus of a cell and forms chromosomes, as shown in Figure \(\PageIndex{32}\). Sci. In the next section, we will study the functions of RNA, which are much more numerous and complicated. However, over 50% of the human genome consists of widely dispersed repetitive sequences. The function and organization of cells and organisms are determined by the type and quantity of protein contained therein. The purine and pyrimidine residues are reused by several salvage pathways to make more genetic material. During normal cell metabolism, RNA is constantly being made and broken down. 47. e73. Chapter in: R. Hardisons Working with Molecular Genetics. Figure \(\PageIndex{1}\) shows a low resolution comparison of the structure of DNA and RNA. Retrieved 16:19, July 26, 2019, from en.Wikipedia.org/w/index.php?title=Histone&oldid=907472227, Wikipedia contributors. In just the same way, living organisms need intact copies of their DNA source code to function. The two main types of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).DNA is the genetic material found in all living organisms, ranging from single-celled bacteria to multicellular mammals. Unacademy is Indias largest online learning platform. Journal of Nucleic Acids 2010, Article ID: 290935, DOI: 10.4061/2010/290935 Available at: https://www.hindawi.com/journals/jna/2010/290935/, Mechanobiology Institute (2018) What are chromosomes and chromosome territories? (eds.) One of the main biological functions of nucleic acids is storing the genetic code from the forefathers and transmitting them to the offspring. A more detailed description of polymerase reaction mechanisms will be covered in Chapters X and Y, covering DNA Replication and Repair, and DNA Transcription. So, can any two bases decide to get together and form a pair in the double helix? 248 The CRISPR/Cas system was originally discovered in bacteria and shows an antiviral function by cleaving nucleic acids that . (Assuming that you are refering to DNA and RNA) DNA is really important for cell division (which is important for growth, development, and regeneration) and stores genetic information. All nucleic acids contain the bases A, C, and G; T, however, is found only in DNA, while U is found in RNA. They also must have at least 2 stacked triads. The biological function of DNA is quite simple, to carry and protect the genetic code. The extension caused by these ethers and natural extensions would decrease base stacking but appear at the same time strengthening the hydrogen bonding between bases. DNA and RNA are both found in all living cells. Bases fit in the double helical model if pyrimidine on one strand is always paired with purine on the other. Prokaryotic Chromosomes (2017) In MediaWiki, Available at: https://www.wikilectures.eu/w/Prokaryotic_Chromosomes, Wikipedia contributors. Similarly, RNA polymerases are required for RNA synthesis. Biology Dictionary. Ribosomes the cellular machines that make protein and some enzymes are made out of RNA. Based on nature, structure, and function, the nucleic acids are categorized into two groups: Deoxyribonucleic acids (DNA) and Ribonucleic acids (RNA). The noncanonical structures are also important for RNA-protein interactions in the RNA region which binds proteins. Available at: https://www.mechanobio.info/genome-regulation/what-are-chromosomes-and-chromosome-territories/, National Human Genome Research Institute (2019) The Human Genome Project. In this article, we will study nucleic acids, types of nucleic acids like DNA and RNA, their basic structure, and the biological functions of nucleic acids. Will the molecular structure of DNA become like RNA? Some Nucleotides Are Regulatory Molecules. Today, scientists know that the source code for cells is quite literally written in nucleic acids. A creationist would say that this is part of the intelligent design. We will consider four different types of noncanonical base pairing: reverse Watson Crick, wobble, Hoogsteen and reverse Hoogsteen base pairs. Mech., Holderness School, Plymouth, N. H. Kornberg, A., DNA Synthesis. Additionally, they participate in cell signaling and form a second messenger in cellular processes. Outside of the nucleus, movements of organelles, vesicles, and other cellular components could easily damage the long, complex DNA strands. Notice in the image the ribose molecule has one more OH group than the deoxyribose molecule. Figure \(\PageIndex{5}\) shows an interactive iCn3D model of the the iconic structure of a short oligomer of double-stranded DNA (1BNA). Scientists are still discovering new varieties of noncoding RNA. For example. This allows each base to match up with its partner: These two strands are complementary, with each base in one sticking to its partner on the other. Springer, Berlin, Heidelberg. Human lactoferrin (LF) is a remarkable protein possessing many independent biological functions, including interaction with DNA. The triple helical structure of nucleic acids was discovered ~30 years ago and has potential importance in biological functions.1 X-ray diffraction data for polynucleotide triplex fibers provided a basic structural scheme for pyrimidine-purine-pyrimidine triplexes. This page titled 8.1: Nucleic Acids - Structure and Function is shared under a CC BY-SA 4.0 license and was authored, remixed, and/or curated by Henry Jakubowski and Patricia Flatt. Direct link to Ivana - Science trainee's post This one is the best expl. There are also examples of reverse Hoogsteen base pairing, as shown in Figure \(\PageIndex{26}\). In molecular biology shorthand, the nitrogenous bases are often just referred to by their one-letter symbols, A, T, G, C, and U. DNA contains A, T, G, and C, while RNA contains A, U, G, and C (that is, U is swapped in for T). In the nucleus, nucleotide monomers are linked together . Given that the hydrogen bond donors and acceptors that contribute to base pairing exist in the absence of competing water, the donors and acceptors are free to fully engage in bonding. The DNA molecule is composed of units called nucleotides, which comprise three distinct components, such as phosphate groups, nitrogen bases, and sugar. It is also used for the identification of criminals. Thus, when each strand of the double-stranded parental DNA molecule separates during replication from its complement, each serves as a template for synthesizing a new complementary strand. From Chargaffs rules, the two strands will pair A with T and G with C. This pairs a keto base with an amino base, a purine with a pyrimidine. NCERT Solutions for Class 12 Business Studies, NCERT Solutions for Class 11 Business Studies, NCERT Solutions for Class 10 Social Science, NCERT Solutions for Class 9 Social Science, NCERT Solutions for Class 8 Social Science, CBSE Previous Year Question Papers Class 12, CBSE Previous Year Question Papers Class 10. Damage to DNA would cause cells and organisms to develop incorrectly, or be so badly damaged that they simply died. In Wikipedia, The Free Encyclopedia. Biologydictionary.net, September 07, 2017. https://biologydictionary.net/nucleic-acid/. In DNA, these types of noncanonical base pairs can occur when bases become mismatched in double-stranded regions. Only two nucleic acids are believed to exist in nature: DNA and RNA, or ribonucleic acid. Hence they can occur naturally. We also explored them dynamically using molecular dynamic simulations. Bases include the pyrimidine bases (cytosine, thymine in DNA, and uracil in RNA, one ring) and the purine bases (adenine and guanine, two rings). A major function of nucleic acids involves the storage and expression of genomic information. Biologydictionary.net Editors. For example, DNA contains two such chains spiraling round each other in the famous double helix shape. Human genome. In RNA the nucleotide bases are ribose, and the common pyrimidine bases are uracil and cytosine. The well-known . These nitrogenous bases bond to each other in specific combinations to form the "rungs" of the DNA ladder in its unwound form. Figure \(\PageIndex{7}\) shows an interactive iCn3D model of the tertiary structure of the T4 hairpin loop on a Z-DNA stem (1D16). Nat Commun 9, 889 (2018). It plays a key factor in transferring genetic information from one generation to the next. Would it be possible for DNA and RNA to use other sugars aside from Deoxyribose and Ribose? To understand this process, it may be useful to compare the DNA code to the binary code used by computers. Learn about nucleic acids, biological functions of Nucleic Acids, and topics related to them. Scientists did exactly that in 2010, using an artificial DNA synthesizer to write a genome from scratch using bits of source code taken from other cells. In this article we summarise the structure and function of nucleic acids. Nucleotides and polynucleotides. They are naturally occurring chemical compounds. In the next section, we will study the functions of RNA, which are much more numerous and complicated. These molecules are fairly complex, consisting of a nitrogenous base plus a sugar-phosphate backbone. There are four basic types of nucleotide, adenine (A), guanine (G), cytosine (C), and thymine (T). Download our apps to start learning, Call us and we will answer all your questions about learning on Unacademy, Access free live classes and tests on the app, Kerala Plus One Result 2022: DHSE first year results declared, UPMSP Board (Uttar Pradesh Madhyamik Shiksha Parishad), Attempt 2023s and previous years JEE Main, Attempt Free Test Series for JEE Main 2023. For example, the HIV Rev peptide binds to a target site in the envelop gene of HIV (which has an RNA genome) and leads to the formation of an RNA loop with hydrogen bonding between two purines. In each layer, 4 noncontiguous guanine bases interact with a K+ ion. The cells encode the information into nucleic acids. There are majorly three types of DNA. Nucleic acids are the main information-carrying molecules of the cell, and, by directing the process of protein synthesis, they determine the inherited characteristics of every living thing. Triple helices can form when single stranded DNA formed during replication, transcription or DNA repair with half of the required mirror symmetry folds back into the adjacent major grove and base pairs using Hoogsteen/reverse Hoogsteen bonding, which can be stabilized by Mg2+. An extended chain connects the DNA binding and interaction domains of each protein. 2008 3DNA Nature Protocols paper (NP08), the initial 3DNA Nucleic Acids Research paper . Nucleic acids consist of a series of linked nucleotides. Thus, DNA is directional and is always synthesized in the 5 to 3 direction. The prior model was triple-stranded DNA. 1, 595614. assignment brief awarding body btec pearson qualification level extended diploma in applied science unit Skip to document Ask an Expert Sign inRegister Sign inRegister Home Ask an ExpertNew Two Hbonds can form between A and T, and three can form between G and C. This third H-bond in the G:C base pair is between the additional exocyclic amino group on G and the C2 keto group on C. The pyrimidine C2 keto group is not involved in hydrogen bonding in the A:T base pair. When transcription takes place and the DNA is broken into two, and then mRNA is formed with one of the DNA strands or for BOTH the DNA strands? (1974) Nucl. Two main functions of nucleic acids are: (i) DNA is responsible for the transmission of inherent characters from one generation to the next. Nitrogenous Base Types of Nucleotide Bases 1. These include the Purines: Adenine (A) and Guanine (G), and the Pyrimidines: Cytosine (C) and Thymine (T). (a) Base pair orientation with x, y, and z axes result in different kinds of rotation (tilt, roll or twist) or slipping of the bases (slide, flip) regarding to the helix central axis. Depending on the DNA sequence, denaturation (melting) can be local or widespread and enables various crucial cellular processes to take place, including DNA replication, transcription, and repair. Which of the following are functions of nucleic acids? Figure \(\PageIndex{8}\) shows an interactive iCn3D model of pseudoknot in RNA (437D). Not only this, but they are also essential for transferring information to new cells or the next generation of the living organisms. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. DNA reserves genetic information and is responsible for maintaining the identity of species over the centuries. A major function of nucleic acids involves the storage and expression of genomic information. Figure \(\PageIndex{16}\): A, B and Z-DNA. As structure determines function and activity, these alternative structures also influence DNA/RNA function. DNA is guided by the development and reproduction of an organism - ultimately, its survival. Biology, 21.06.2019 20:40. Therefore, RNA clearly has the extra ability to serve as genetic information. Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree. Vedantu LIVE Online Master Classes is an incredibly personalized tutoring platform for you, while you are staying at your home. Direct link to kind of blue's post How do mRNA and tRNA comm, Posted 7 years ago. These are just some examples out of many types of noncoding and regulatory RNAs. "Nucleic Acid. (eds.) There are five types of nitrogenous bases in nucleic acids: adenine (A), cytosine (C), guanine (G), thymine (T) and uracil (U). The well-known structure of the DNA double helix allows this information to be copied and passed on to the next generation. Deoxyribonucleic acid, or DNA, encodes the information cells need to make proteins. The 3 bases on the mRNA are called the codon, and the 3 complementary bases on the tRNA are called the anticodon. Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are both types of nucleic acid. Nucleic acids play an important role in the storage and transfer of genetic data from one cell to another. Direct link to Prakriti Marwah's post When transcription takes , Posted 6 years ago. Stereoisomers [5] Purines: Purines are two carbon-nitrogen rings. A nucleic acid is a chain of nucleotides which stores genetic information in biological systems. Dilauro, R., Rosenberg, M., de Combrugghe, B., N.I.H./Sklarr, J., Weissman, S.M. Various types of enzyme cofactors that serve a wide range of chemical functions comprise of adenosine as part of their structure. We will study packing of DNA in other sections. (2019, July 26). Recently, similar studies have been conducted using yeast, cultivated mammalian cells, and insect and mammalian embryos as recipients and cloned DNA as a donor of genetic material. The double-helix model of DNA structure was first published in the journal Nature by James Watson and Francis Crick in 1953,(X,Y,Z coordinates in 1954) based upon the crucial X-ray diffraction image of DNA from Rosalind Franklin in 1952, followed by her more clarified DNA image with Raymond Gosling, Maurice Wilkins, Alexander Stokes, and Herbert Wilson, and base-pairing chemical and biochemical information by Erwin Chargaff. Retrieved 02:41, July 22, 2019, from https://en.Wikipedia.org/w/index.php?title=DNA&oldid=905364161, Wikipedia contributors. Viruses are increasingly recognised as important components of the human microbiome, fulfilling numerous ecological roles including bacterial predation, immune stimulation, genetic diversification . Monosaccharide Glucose and galactose can be described as which of the following? Creative Commons Attribution License. The A-T pairs are connected by two hydrogen bonds, while the G-C pairs are connected by three hydrogen bonds. Nucleic acids are naturally occurring chemical compounds that serve as the primary information-carrying molecules in cells. In both cases the end product is a nucleotide carrying a phosphate attached to the 5 carbon on the sugar. (c) Mono- or bis-intercalation of a small molecule (shown in blue) between adjacent base pairs resulting in an unwinding of the DNA helix (orange arrow on the top) and a lengthening of the DNA helix (Length) depending on the X and y values that are specific for a defined DNA intercalating compound. Nucleic acids are polynucleotidesthat is, long chainlike molecules composed of a series of nearly identical building blocks called nucleotides. RNA is the genetic material of certain viruses, but it is also found in all living cells, where it plays an important role in certain processes such as the making of proteins. Direct link to shreya punniamoorthy's post Yes, all 46 chromosomes a, Posted 7 years ago. recognizes specific DNA sequence. Figure \(\PageIndex{3}\) below shows a "flattened" structure of double-stranded B-DNA that best shows the backbone and hydrogen bonded base pairs between two antiparallel strands of the DNA. This may seem paradoxical, especially given the apparently simplicity of the iconic structure of DNA presented in textbooks. In addition to the major and minor grooves providing variation within the double helix structure, the axis alignment of the helix along with other influencing factors such as the degree of solvation, can give rise to three forms of the double helix, the A-form (A-DNA), the B-form (B-DNA), and the Z-form (Z-DNA) as shown in Figure \(\PageIndex{14}\). Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions for the development and function of living things. Each nucleic acid contains four of five possible nitrogen-containingbases:adenine(A),guanine(G),cytosine(C),thymine(T), anduracil(U). Apart from nucleic acids, adenosine triphosphate (ATP), which is a type of . RNA uses the same nitrogenous bases as DNA, except for Thymine. https://www.khanacademy.org/science/organic-chemistry/aromatic-compounds/aromatic-stability/v/aromatic-heterocycles-i, https://en.wikipedia.org/wiki/Heterocyclic_compound, https://en.wikipedia.org/wiki/Abiogenesis, https://en.wikipedia.org/wiki/Nucleic_acid_analogues, https://www.sciencedaily.com/terms/rna.htm, Involved in protein synthesis and gene regulation; carrier of genetic information in some viruses. In DNA, the nucleotides contain 2-deoxyribose, and the common pyrimidine bases are thymine and cytosine. Figure \(\PageIndex{27}\) shows an interactive iCn3D model of parallel quadruplexes from human telomeric DNA (1KF1). The primary act of nucleic acid is to store information. Research primarily focused on macromolecules structural biology, which involves studying the three-dimensional structures, functions, and interactions of large biological molecules such as . A consequence of the structure of nucleotides is that a polynucleotide chain has, As new nucleotides are added to a strand of DNA or RNA, the strand grows at its 3 end, with the 5 phosphate of an incoming nucleotide attaching to the hydroxyl group at the 3 end of the chain. Our goal is to make science relevant and fun for everyone. The TFO binds along the major grove of the D2 strand which is purine rich. The hydrogen-bonded interstrand base pairs are shown alternatively in spacefill and sticks to illustrate how the bases stack on top of each other. (1976) Gordon Res. Please refer to the appropriate style manual or other sources if you have any questions. 10.1093/nar/gkz237. Reverse Hoogsteen hydrogen bonds can also occur. Ed. Nucleic acids are categorised into two different forms, DNA, i.e., Deoxyribonucleic Acid and RNA, i.e., Ribonucleic Acid. Please refer to our Nucleic Acid Structure article for more information. Note that this is just a few of the rol. These molecules make up the bulk of a cell's dry mass when combined (recall that water makes up the majority of its complete mass). DNA supercoil. Marginal stability is important as protein conformation often must be perturbed on binding and ensuing function. The same must be true of double-stranded DNA, which must "unfold' or separate on replication, transcription and repair. It is the source of information for the synthesis of all cell and organism protein molecules, and it provides the information that daughter cells or offspring have inherited. The excess stability of dsDNA enriched in GC base pairs can still be explained by the extra stabilization for an additional hydrogen bond per GC base pair. The stacking energy has been shown to be similar for an AT - AT stack and a GC-GC stack (about -9.8 kcal/mol, 41 kJ/mol). Decades of research have established that the m7G cap serves as a unique molecular module that recruits cellular proteins and mediates cap-related biological functions such as pre-mRNA processing, nuclear export and cap-d mRNA capping: biological functions and applications Nucleic Acids Res. Unit 11 Structure & Function Of Nucleic Acids - Assignment Brief Awarding Body BTEC Pearson - Studocu This is the first assignment and recieved distinction. These scholars actually referred to the agent (later shown to be DNA) that accomplished the change as a "transforming factor." Histone. (2016) Metal ion induced heterogeneity in RNA folding studied by smFRET. Deoxyribonucleic acid, or DNA, encodes the information cells need to make proteins. Modulation of Figure \(\PageIndex{xx}\)Hoogsteen dynamics on DNA recognition. Aluminium silicate zeolites are microporous three-dimensional crystalline solids. Cells also use nucleic acids for other purposes. Such RNAs may be called regulatory RNAs. DNA is the genetic material found in all living organisms, ranging from single-celled bacteria to multicellular mammals. Sets of three nucleotides, called codons, can code for any given amino acid, or for the stop or start of protein production. Figure \(\PageIndex{17}\): Base pair orientation and corresponding parameters in nucleic acids. This observations support the simple notion that interbase hydrogen bonds is the source of dsDNA stability. Our editors will review what youve submitted and determine whether to revise the article. A related type of nucleic acid, called ribonucleic acid (RNA), comes in different molecular forms that . Takanami, M., Sugimoto, K., Sugisaki, H., Okamoto, T. (1976) Nature (London) 260, 297302. If a segment is longer than others, a G might be in a loop. How Nucleic Acids Work They can bind tightly and specifically and in a parallel or antiparallel fashion. Another major function of nucleic acids is protein synthesis, where RNA functions as an adapter molecule. Nucleic acids are responsible for the transmission of inherent characters from parent to offspring. As with proteins, the three-dimensional structure of an RNA molecule specifies a unique function in cells, including the degradation of enzymes. Furthermore, slide or flip effects can also modify the geometrical orientation of the helix. They are the cell's main information-carrying molecules and they ultimately determine the inherited traits of every living organism by guiding the entire process of protein synthesis. Water around the wobble base pairs can form hydrogen bonds and stabilize the pair if an hydrogen bond is missing. The processes of DNA replication and repair will be discussed in more detail in Chapter 28. The nucleic acids are vital biopolymers found in all living things, where they function to encode, transfer, and express genes. Sugimoto, K., Sugisaki, H., Okamoto, T., Takanami, M. (1975) Nucl. (ii) DNA also transfer genetic information from one generation to other. These structures can occur in DNA (and also RNA) that contain homopurine and homopyrimidine sequences that have a mirror repeat symmetry. And if this is true, are these parts (AT only parts) more prone to mutations? Both consist of polymers of a sugar-phosphate-sugar backbone with organic heterocyclic bases attached to the sugars. All living cells on Earth read and write their source codes in almost exactly the same language using nucleic acids. For that decoding process to occur, two RNA molecules, messenger RNA (mRNA) and a transfer RNA (t-RNA) covalently attached to a specific amino acid like glutamic acid, must bind to each other through a 3 base pair interaction. Would it be possible for there to be nitrogenous bases with more than two fused carbon rings? A first glance at a DNA or RNA structure reveals a myriad of possible hydrogen bond donors and acceptors in the bases of the nucleic acid. 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). Lab. They write new content and verify and edit content received from contributors. In addition to lipids and polysaccharides, proteins are components of the cell structure. A molecule in the backbone of DNA and RNA that links adjoining bases together. Direct link to Alex Auvenshine's post Are the functions of nucl, Posted 7 years ago. Google Scholar. Download preview PDF. 2008. doi: 10.1016/j.biochi.2008.02.011. Provided by the Springer Nature SharedIt content-sharing initiative, Over 10 million scientific documents at your fingertips. The Function of DNA & RNA. They showed that by introducing purified DNA from the former coccus into the latter, the genetic determination of the character (type) of the capsule of specific pneumococcus could be transmitted to another capsular type. Ribonucleic acid was also used to pass down instructions from generation to generation by some viruses. You would be in general correct in this belief, but you'd be missing the more important contributor to ds-DNA stability, base () stacking and the noncovalent interactions associated with the stacking. The tRNA that binds, and thus the amino acid that's added, at a given moment is determined by the sequence of the mRNA that is being "read" at that time. There are an extraordinary number of arginines which form ion-ion interactions with the negatively charged phosphates in the major grove of this double-stranded A-RNA. Nucleic acids are formed mainly with the elements carbon, oxygen, hydrogen, nitrogen, and phosphorus. Direct link to Greacus's post If A-T bonds have 2 hydro, Posted 6 years ago. Each daughter cell contains DNA molecules with specific information remarkably similar to that possessed by the parent; however, the parent cell's DNA molecule was only semi-conserved in each daughter cell. In a series of experiments by Avery, MacLeod, and McCarty, the demonstration that DNA contained the genetic information was first made in 1944. Its these RNA copies of genetic information which are sent out of the nucleus and around the cell to be used as instructions by cellular machinery. Nearly all of the various RNA species are involved in some aspects of the synthesis of proteins. Amino acids have several functions. Check out this, Posted 7 years ago. Acids Res. They can also occur when a third single-strand DNA (called a triplex forming oligonucleotide or TFO) binds to a double-stranded DNA. If the Deoxyribose in DNA is replaced with Ribose, what will happen? Zeolites have small, fixed-size openings that allow small molecules to pass through easily but not larger molecules; this is why they are sometimes referred to as molecular sieves. Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. However as our ability to record information on silicon has advanced, little attention has been given to research into genetic computers.. a. Deoxyribonucleic acids (DNA) DNAs are the hereditary material that resides inside the nucleus. Nucleic acids consist of a series of linked nucleotides. In Wikipedia, The Free Encyclopedia. The N-terminal fragment binds to conserved CCG triplets found at both ends of the DNA in the major grove. The protein shown is actually a dimer held together by a short coiled-coil interaction domain so the site has 2-fold symmetry. USA 72, 737741. (iv) Some RNAs act as enzyme. A wobble base, U43-G77, see below, is shown as well as three homopurine base pairs, G47-A73, G55-A58 and G48-G71. Maniatis, T. Ptashne, M., Backmann, K., Kleid, D., Flashman, S., Jeffrey, A., Maurer, R. (1975) Cell 5, 109113. The two sugar-phosphate backbones are shown in green and yellow. Molecular Genetics (Biology): An Overview, Scitable by Nature Education: Nucleic Acid Structure and Function, Dallas County Community College District: Nucleic Acid. Part of Springer Nature.