This is one of 4 kinds of units for constructing a multi-unit model of a molecule of deoxyribonucleic acid in double helix configuration: a stack of about 15 units will illustrate the principle, but the actual molecules contain about 12,900 such units if we accept a molecular weight of 8 million. Mutation & DNA Damage Causes & Examples | What Causes Mutations? = (An x 329.2) + (Un x 306.2) + (Cn x 305.2) + (Gn x 345.2) + 159 An, Un, Cn, and Gn are the number of each respective nucleotide within the polynucleotide. The purines are adenine and guanine. Protonation of thymine, cytosine, adenine, and guanine DNA nucleic acid bases: Theoretical investigation into the framework of density functional theory Journal of Computational Chemistry, 1998 Andr Grand Adenine and guanine are purines and thymine and cytosine are pyrimidines. The thousands or millions of bases that make up the DNA molecule make enough hydrogen bonds to hold the two strands of DNA together throughout the entire length of the molecule. The experimental and theoretical gas phase acidities of adenine, guanine, cytosine, uracil, thymine and halouracils. Enrolling in a course lets you earn progress by passing quizzes and exams. D) Adenine pairs with cytosine in DNA and with guanine in RNA. Wiki User. The guanine nucleoside is called guanosine . Definition. The perpetual combination of a purine paired with a purine maintains a constant width of exactly 2.3 nm. Adenine pairs with what in DNA? UExcel Anatomy & Physiology: Study Guide & Test Prep, Anatomy and Physiology: Certificate Program, Introduction to Biology: Certificate Program, Human Anatomy & Physiology: Help and Review, UExcel Microbiology: Study Guide & Test Prep, 6th Grade Life Science: Enrichment Program, 7th Grade Life Science: Enrichment Program, 8th Grade Life Science: Enrichment Program, Microbiology Syllabus Resource & Lesson Plans, Create an account to start this course today. Correct Response The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Missense Mutation | Concept, Examples & Variant. Therefore, each strand will always have a phosphate at one end and a sugar at the other end. Journal of molecular biology, 273(1), 171-182 (1997-11-21) A. J . calculated is valid at physiological pH. Thus, one strand of the DNA molecule begins 5' (phosphate) and ends 3' (sugar), while the other starts with a 3' (sugar) end and ends with a 5' (phosphate) end. . [10][11], In medicine, several nucleoside analogues are used as anticancer and antiviral agents. 23. Guanine The chemical structure of guanine ( G) is C5H5N 5O C 5 H 5 N 5 O. Thymine Structure & Function| What is Thymine? Nucleotide Structure, Parts & Function | What is a Nucleotide? Life at the Molecular Level 5th Edition Charlotte W. Pratt, Donald Voet, Judith G. Voet. The single-ring nitrogenous bases, thymine and cytosine, are called pyrimidines, and the double-ring bases, adenine and guanine, are called purines. Notice that the specific positioning required for hydrogen bonding is only made possible by the inverted nature of one of the two strands. C and T bases, which have just one ring, are called pyrimidines, while A and G bases, which have two rings, are called purines. Polynucleotide Chain Structure & Overview | How do Nucleotides Link Together? Except for the Thymine, which is replaced by uracil, RNA has the same nitrogen bases as DNA: adenine, guanine, and cytosine. As seen above, complementary bases bond together through hydrogen bonds, formed when electronegative atoms (atoms strongly attracted to electrons, which gives them a slight negative charge) come close to slightly positive hydrogen atoms (hydrogen atoms only have one proton, so they are only weakly attached to their electrons. The Journal of Organic Chemistry 2003, 68 (11) , 4439-4445. The derivatives of purine are called adenine (A) and guanine (G). However, for two entire strands of DNA to pair together, one strand must be "upside-down" relative to the other; this means the two strands are antiparallel to each other they run in opposite directions (see figure). Guanine and cytosine bonded base pairs are stronger then thymine and adenine bonded base pairs in DNA. Create your account. In nucleic acid: Basic structure. However, the nitrogenous bases can't hydrogen-bond in this orientation. . Point Mutation Facts | What is a Point Mutation? It's an important base because it's used not only in DNA and RNA, but also for the energy carrier molecule ATP, the cofactor flavin adenine dinucleotide, and the . Adenine is a purine found in all DNA, RNA and ATP. UExcel Anatomy & Physiology: Study Guide & Test Prep, Anatomy and Physiology: Certificate Program, Introduction to Biology: Certificate Program, Human Anatomy & Physiology: Help and Review, UExcel Microbiology: Study Guide & Test Prep, 6th Grade Life Science: Enrichment Program, 7th Grade Life Science: Enrichment Program, 8th Grade Life Science: Enrichment Program, Microbiology Syllabus Resource & Lesson Plans, Create an account to start this course today. Gas chromatography (GC) has been examined for the ease of separation of the nucleobases guanine (G), adenine (A), cytosine (C), thymine (T), and uracil (U) after precolumn derivatization with isobutyl chloroformate. Because the bases can only fit together in a specific orientation, a parallel orientation between the strands won't work. These extra oxygen atoms allow Guanine to form an extra hydrogen bond, accounting for its extra stability when compared to Adenine. Beilstein: 9680. Gas-phase clusters of water with DNA bases [guanine (G), cytosine (C), adenine (A), and thymine (T)] are generated via thermal vaporization of the bases and expansion of the resultant vapor in a continuous supersonic jet expansion of water seeded in Ar. Abbreviations: C-cytosine; T-thymine; G-guanine; A-adenine; -stretching. Let me stop you again, Professor, so I can summarize your testimony for the jury. Its chemical structure is shown below. Gravity. Adenine and guanine are purines, but we're getting off track. Molecular mass 135.13 g/mol Melting point 360 - 365 C CAS number 73-24-5 . Click again to see term . by directing the process of protein synthesis. Well, hydrogen bonding completes the ladder. Cytosine, thymine, and uracil are pyrimidines. Thymine has a molar mass of 126.115 g/mol and a melting point of 316 to 317 C. Find Study Materials Expert Answer Adenine (C5H5N5) = 512+51+514 = 1 View the full answer Previous question Next question To understand of the mechanism of self-assembly of DNA base molecules on the Au(111) surface, molecular dynamics simulations of different surface coverage of guanine, adenine, cytosine, and thymine molecules at 300 and 400 K are performed. Adenine, cytosine, thymine and guanine are the four main nucleobases found in nucleic acids DNA and RNA. 24. I highly recommend you use this site! However, during transcription (when base-pairing is used to make the pre-mRNA based on the DNA sequence) and in translation (when the mRNA codons pair with tRNA anti-codons), adenine pairs with uracil; this is because there is no thymine (adenine's usual base-pairing partner) in RNA. Discover the base pairs of these nitrogenous bases and why DNA strands are antiparallel. Chargaff's Rule. In RNA, thymine is replaced by the nucleobase uracil. These compounds are activated in the cells by being converted into nucleotides; they are administered as nucleosides as charged nucleotides cannot easily cross cell membranes. (Deoxyribose is the name of the sugar found in the backbone of DNA.) The strands must be antiparallel, or upside-down, relative to one another. - Definition, Causes & Facts, Physics 101: Intro to Physics Formulas & Constants, Working Scholars Bringing Tuition-Free College to the Community, Adenine can also pair with Uracil in RNA (again forming 2 hydrogen bonds). Point Mutation Facts | What is a Point Mutation? Cookie Notice bob hayes wife . Guanine gets girls with an erect penis (carbonyl is "upright") Cytosine has a big cock (carbonyl is NOT upright but toward the "bottom" of the six membered ring just as a flaccid penis is positioned on the male body) Thymine has two tits (the two carbonyls constitue the tits) Adenine and it's complete lack of carbonyls is all that's . Question 3. Thereby keeping the DNA stable and (mostly) unchanging an important role when any change (mutation) could produce a dangerous genetic disease! The pyrimidines are cytosine, thymine, and uracil. calculated is valid at physiological pH. The chemical structure of cytosine (C) is {eq}C_{4}H_{5}N_{3}O {/eq}. You were telling us why the chemical structure of nucleotides is important. Furthermore, molecular relaxation processes associated with global relaxation times which varied from 0.47 to 0.59 ps have been observed for the peak around 1363 cm-1 in the case of nucleic . Molecular mass 111.102 g/mol Melting point: 320 - 325C (decomp) CAS number 71-30-7 . . by breaking down proteins within the cell. Creation of polynucleotide-assisted molecular assemblies in organic solvents: general strategy toward the creation of artificial DNA-like nanoarchitectures . succeed. There is no online registration for the intro class The four different bases pair together in a way known as complementary pairing. DNA is often said to resemble a "twisted ladder." Enrolling in a course lets you earn progress by passing quizzes and exams. Adenine is a bicyclic molecule while Guanine is a tricyclic molecule . The ability of nucleobases to form base pairs and to stack one upon another leads directly to long-chain helical structures such as ribonucleic acid (RNA) and deoxyribonucleic acid (DNA). The other four nucleobases are adenine, guanine, thymine, and uracil. = (An x 329.2) + (Un x 306.2) + (Cn x 305.2) + (Gn x 345.2) + 159 An, Un, Cn, and Gn are the number of each respective nucleotide within the polynucleotide. Q. Contents 1 Properties 2 History The basic building components of RNA are adenine and uracil, which form a base pair with the assistance of two hydrogen bonds. Learn about the DNA bases adenine, thymine, guanine, and cytosine. If all adenine bonds to uracil and all cytosine pairs with guanine, then the sum of all adenine will never be equal to the sum of all uracil in an RNA molecule. Answer (1 of 3): So if a molecule has 30% Guanine then it will contain 30% of Cytosine as well. All of the components of ribonucleic acid are identical to those of DNA, with only two exceptions. cottonwood financial administrative services, llc, Step By Step Peekaboo Hair Color Placement, iowa swimming short course championships 2021. I would definitely recommend Study.com to my colleagues. Adenine has a molecular mass of 135.13 g and it seems to be crystalline and varies from light yellow to white in colour. molecular weight of adenine, guanine cytosine, thymine. A purine always pairs with a pyrimidine and vice versa. Molecular mass of guanine is . The squiggly lines indicate where each base would connect to a sugar and the rest of the DNA strand. Can you tell us how nucleotide structure pertains to the case at hand? Missense Mutation | Concept, Examples & Variant. decomposes In water, it dissolves at a rate of 0.103 g/100 mL. The main difference between nucleobase adenine and guanine is that complementary base pairs in adenine are formed with uracil in RNA and thymine in DNA. So adenine=40%, thymine=40%, guanine=10% & cytosine=10% Nucleic Acid Molecular Weight Conversions Exact M.W. step by step explanations answered by teachers StudySmarter Original! Expert Answer Adenine (C5H5N5) = 512+51+514 = 1 View the full answer Previous question Next question COMPANY Abbreviations: C-cytosine; T-thymine; G-guanine; A-adenine; -stretching. 24 chapters | Simply put, there are five major bases found in the DNA and RNA in cells. Adenine must pair with uracil in RNA because RNA does not contain any thymine (adenine's normal base-pairing partner). Uracil Structure & Location | Is Uracil Found in DNA? DNA Base Pair Types & Examples | What is a Base Pair? I feel like its a lifeline. Mnemonic in case you don't wanna logic it out: Got A Tattoo UnderCover. Read More. We have recently determined the crystal structures of several DNA fragments with guanine o thymine and adenine o guanine mismatches in a full turn of a B-DNA helix and now report the nature of the . Adenine pairs with what in DNA? It differs in having an extra amine group, creating a more stable bond to thymine.[2]. copyright 2003-2023 Study.com. Thus, cytosine, along with adenine and guanine, is present in both DNA and RNA, whereas thymine is usually seen only in DNA and uracil only in . The abnormal levels of four DNA bases, namely guanine (G), adenine (A), thymine (T), and cytosine (C) are implicated in several cancers, metabolic diseases, and HIV/AIDS. Adenine pairs with Thymine or Uracil. D ) uracil. The chemical formula of the pyrimidine thymine is C 5 H 6 N 2 O 2. These base-pairing rules ensure that, given the sequence of one strand of DNA (e.g., GATAGGA), the complementary sequence of the opposing strand can be determined (in this case, CTATCCT). of a 5' triphosphate. Comparative Genomics: Prokaryotes vs Eukaryotes. What are Adenine, Thymine, Guanine, and Cytosine? All life on Earth uses DNA as its genetic material, and all DNA is made from only four different nitrogenous (nitrogen-containing) bases adenine, cytosine, guanine, and thymine. Molar mass: 135.13 g/mol: Appearance: white to light yellow, crystalline: Density: 1.6 g/cm 3 (calculated) . Show your work. Each of the base pairs in a typical double-helix DNA comprises a purine and a pyrimidine: either an A paired with a T or a C paired with a G. These purine-pyrimidine pairs, which are called base complements, connect the two strands of the helix and are often compared to the rungs of a ladder. Nucleobases, also known as nitrogenous bases or often simply bases, are nitrogen-containing biological compounds that form nucleosides, which, in turn, are components of nucleotides, with all of these monomers constituting the basic building blocks of nucleic acids. Miss Crimson: What do you mean antiparallel? A modest electron-transfer effect is found in the Watson-Crick adenine-thymine (AT), guanine-cytosine (GC) and Hoogsteen adenine-thymine (H-AT) pairs, confirming the weak covalence in the hydrogen bonds. Cytosine (C) is one of the four nucleotide bases in DNA, with the other three being adenine (A), guanine (G) and thymine (T). In RNA, the thymine is replaced by uracil (U). Guanine has the molecular formula C 5 H 5 N 5 O with molecular weight of 151 am u. Adenine is C 5 H 5 N 5 (molecular weight 135 am u), cytosine is C 4 H 5 N 3 O (molecular weight 111 am u) and thymine is C 5 H 6 N 2 O 2 (molecular weight 126 am u). Or, if I may make an analogy to the case at hand, the information in DNA is like a recipe in one of our poor victim's cookbooks. (Miss Crimson has a puzzled look.) Adenine (sometimes known as vitamin B4) combines with the sugar ribose to form adenosine, which in turn can be bonded with from one to three phosphoric acid units, yielding AMP, ADP and ATP.These adenine derivatives perform important functions in cellular metabolism. Get unlimited access to over 88,000 lessons. The key can't fit into the lock. In the Chargaff's rules of base pairing are: Relation of A with T: The Pyrimidine Thymine (T) always pairs with the Purine Adenine (A) Relation of C with G: The Purine Guanine (G) always pair with the Pyrimidine Cytosine (C) It is steady with there not being enough space (20 ) for two purines to fit within . of ssDNA (e.g., Oligonucleotides): The electrostatic attraction and polarization effects account for most of the binding energies, particularly in the GC pair. Adenine, Thymine, Guanine, Cytosine. Click card to see definition . Thymine and uracil are distinguished by merely the presence or absence of a methyl group on the fifth carbon (C5) of these heterocyclic six-membered rings. Addition of "159" to the M.W. Purine is made of two rings, both containing nitrogen and carbon, fused together to form a single flat structure . Three processes were considered to explain the mechanism assisted by water and formic acid molecules. Using Probability to Solve Complex Genetics Problems, Complementary Base Pairing | Rule & Examples. You see, cytosine can form three hydrogen bonds with guanine, and adenine can form two hydrogen bonds with thymine. adenine, guanine, cytosine, uracil. Discover which bases pair with each other, known as DNA complementary bases and what they do. As mentioned before, each base is classified as either a purine (two-ring molecule) or a pyrimidine (one-ring molecule), as follows: According to Chargaff's rules, a purine base can only pair with a pyrimidine base, and vice versa. It is made up of a six-membered ring attached to a five-membered ring. (Deoxyribose is the name of the sugar found in the backbone of DNA.) That's a very nice mnemonic aid. Molecular biology is the study of Biology at molecular level. Methods: Gas chromatography (GC) has been examined for the ease of separation of the nucleobases guanine (G), adenine (A), cytosine (C), thymine (T), and uracil (U) after precolumn derivatization with isobutyl chloroformate. = (An x 329.2) + (Un x 306.2) + (Cn x 305.2) + (Gn x 345.2) + 159 An, Un, Cn, and Gn are the number of each respective nucleotide within the polynucleotide. Mutation & DNA Damage Causes & Examples | What Causes Mutations? Five nucleobasesadenine (A), cytosine (C), guanine (G), thymine (T), and uracil (U)are called primary or canonical. Purines, from which adenine is derived . This answer is: The cooperative contributions to the H-bonding interaction energies of the adeninethymine and guaninecytosine base pairs have been evaluated using molecular orbital theory. Except for the Thymine, which is replaced by uracil, RNA has the same nitrogen bases as DNA: adenine, guanine, and cytosine. The specific pairing patterns of the bases is determined by the hydrogen bonds they can make: To make the bases "fit" together correctly, the two strands of DNA must be antiparallel to each other, which means one is "upside-down" or "backward" respective to the other. For example, the longest chromosome in the human genome (chromosome 1) is a single DNA molecule containing almost 500 million nucleotides! Interactions of adenine, cytosine, guanine, and thymine with Na(+), Mg(2+), and Zn(2+) cations were studied using an approximate resolution of identity correlated second-order MP2 (RI-MP2) method with the TZVPP ([5s3p2d1f/3s2p1d]) basis set. A) Adenine pairs with thymine in both DNA and RNA. What is the function of cytosine? (Only two of these sites, C-4 and N-3, are used to form base pairs in DNA.) The main difference between adenine and guanine is that adenine contains an amine group on C-6, and an additional double bond between N-1 and C-6 in its pyrimidine ring whereas guanine contains an amine group on C-2 and a carbonyl group on C-6 in its pyrimidine . The chemistry of the nitrogenous bases is really the key to the function of DNA. Like thymine, uracil can base-pair with adenine (Figure 2). The pairing between adenine and thymine, and between guanine and cytosine, results in a complementary relationship between the sequence of bases on the two intertwined chains and gives DNA its self-encoding character. Show your work. In this work, we report on a photoionization study of the microhydration of the four DNA bases. citadel track and field schedule 2022; memorial toponyms example; Home molecular weight of adenine, guanine cytosine, thymine molecular weight of adenine, guanine cytosine, thymine. The deprotonated guanine-cytosine base pair has been studied computationally , . bobby flay restaurant vegas; who was the mother of ilyas bey; what does lcr1 zoning mean; simon city royals book of knowledge; Freundschaft aufhoren: zu welchem Zeitpunkt sera Semantik Starke & genau so wie parece fair ist und bleibt Advertisement Advertisement . Adenine and guanine are purines. Adenine, Thymine, Guanine, Cytosine. . Adenine is one of four nitrogenous bases utilized in the synthesis of nucleic acids. Adenine always pairs with thymine, and cytosine always pairs with guanine. *Uracil is barely 1g heavier than Cytosine in case you were wondering. Concept: A DNA molecule is made up of several nucleotides.Each nucleotide consists of a nitrogenous base, a phosphate group, and a 5-carbon sugar. In DNA, guanine is paired with cytosine. Guanine Overview, Structure & Formula | What is Guanine? As a member, you'll also get unlimited access to over 88,000 A molecular biologist studies the processes of replication, translation and transcription of genetic material on a wide scale. On this Wikipedia the language links are at the top of the page across from the article title. Rather than having to refer to the phosphate or sugar end, scientists simply refer to the ends of the DNA by the closest carbon in the sugar ring. guanine N7 or O6 and adenine N3 Induction of guanine binding to thymine instead of cytosine, leading to extensive DNA damage and, eventually, apoptosis Rapid and complete absorption. . The basic building components of RNA are adenine and uracil, which form a base pair with the assistance of two hydrogen bonds. The bases extend off of this backbone towards the molecule's center. It has a molecular mass of 111.10 g/mol. It is a pyrimidine nucleobase, which is present only in DNA. Cytosine also has a hydrogen acceptor group at C-2. which can be either adenine, guanine, cytosine, or thymine (in the case of RNA, thymine is replaced by uracil). It is important to note that in RNA (RiboNucleic Acid), adenine pairs with uracil because RNA molecules do not contain any thymine. All other trademarks and copyrights are the property of their respective owners. [3] Similarly, the simple-ring structure of cytosine, uracil, and thymine is derived of pyrimidine, so those three bases are called the pyrimidine bases. The single-ring nitrogenous bases, thymine and cytosine, are called pyrimidines, and the double-ring bases, adenine and guanine, are called purines. Bases pair off together in a double helix structure, these pairs being A and T, and C and G. RNA doesn't contain thymine bases, replacing them with uracil bases (U), which pair to adenine 1. - Definition & Structure, Strategies for Coping with Unhealthy Family Behavior, Avoiding & Responding to Unsafe Situations & Behavior, Managing Risk to Enhance & Maintain Your Health, Types of Healthcare Professionals & Delivery Systems, Consumer Health: Laws, Regulations & Agencies, The Role of School Health Advisory Councils in Texas, Working Scholars Bringing Tuition-Free College to the Community, Name the four nitrogenous bases of DNA, identify the base pairs and which are pyrimidines and purines, Explain what antiparallel means in terms of DNA strands. Transcribed Image Text: . J. Mol. These bases form complementary base pairs consisting of one purine and one pyrimidine, with adenine pairing with thymine, and cytosine with guanine. Thymine ( / amn /) ( symbol T or Thy) is one of the four nucleobases in the nucleic acid of DNA that are represented by the letters G-C-A-T. an atom's mass number is 13 and its atomic number is 6. how many neutrons are in its nucleus? M.W. Charrgoff was the scientist that discovered that adenine (A) always equals thymine (T) and that guanine (G) always equals cytosine (C) in DNA. The pairing nature of DNA is useful because it allows for easier replication. Antibody Structural Components & Function | Chains & Domains: Overview & Examples. Adenine and guanine are known as purine bases while cytosine and thymine are known as pyrimidine bases. This relationship between purines and pyrimidines was discovered by Erwin Chargaff in the 1950's. Guanine is a purine (two ring) base, just. According to the given situation, a molecule from a new organism consists of adenine, cytosine thymine and guanine these all are nitrogenous bases which can be found in DNA. DNA stands for deoxyribonucleic acid. The genetic material in the nucleus is DNA, each molecule consisting of two polynucleotide . A nucleotide is made up of a sugar (deoxyribose), a phosphate group, and one of four nitrogenous bases: adenine (A), thymine (T), guanine (G) or cytosine (C). Human DNA consists of about 3 billion bases, and more than 99 percent of those bases are the same in all people. answer choices. Gradientcorrected density functional computations with triplezetatype basis sets were performed to determine the preferred protonation site and the absolute gasphase proton affinities of the most stable tautomer of the DNA bases thymine (T), cytosine (C), adenine (A), and guanine (G). Gas-phase clusters of water with DNA bases [guanine (G), cytosine (C), adenine (A), and thymine (T)] are generated via thermal vaporization of the bases and expansion of the resultant vapor in a continuous supersonic jet expansion of water seeded in Ar. The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Answer: The DNA sequence that produced the mRNA sequence uracil, guanine, cytosine, guanine adenine uracil adenine adenine during transcription is adenine, cytosine, guanine, cytosine, thymine, adenine, thymine, thymine.. A: A species with a small population faces a higher risk of extinction than one with a larger. Molecular Weight: 151.13. Application Thymine has been used as a standard nitrogenous base in high-performance liquid chromatography-ultraviolet (HPLC-UV) for the quantification of bone DNA samples, Raman scattering experiments. Just thought I'd note the nitrogenous bases in order of decreasing molecular weight: Guanine > Adenine > Thymine > Uracil > Cytosine, Mnemonic in case you don't wanna logic it out: Got A Tattoo UnderCover. This unique property of the DNA bases enables the processes of DNA replication, transcription, and translation to occur basically, base pairing allows life itself! cytosine: [noun] a pyrimidine base C4H5N3O that codes genetic information in the polynucleotide chain of DNA or RNA compare adenine, guanine, thymine, uracil. . Purines, from which adenine is derived, are found in plants and animals. Chargaff's Rule of Base Pairing. In the following, selective surface-enhanced Raman modes will be analyzed. For hydrogen bonding to work, the two DNA strands must run in opposite directions. That makes the nucleotide the most basic subunit of DNA, or, more generally, of any nucleic acid. Molecular Weight: 151.13. calculated is valid at physiological pH. Nucleotides are phosphate esters of nucleosides, and the nucleic acids (DNA and RNA) are high molecular weight polymers formed from long chains of four kinds of nucleotide units, which in DNA are derived from adenine, guanine, thymine, and cytosine. Cytosine, thymine, and uracil are pyrimidines. Edit: Want to clarify to because I saw a comment - we do NOT need to memorize the molecular weights for these structures! Adenine (A) has chemical formula of {eq}C_{5}H_{5}N_{5} {/eq}. Adenine pairs with uracil in RNA molecules (e.g., when the rRNA codons pair with tRNA anti-codons in translation or when DNA is transcribed into RNA).