DNA and RNA Nucleic Acids: Structure, Function, and Key Differences

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-08-11

Introduction to Nucleic Acids: DNA and RNA

What Are Nucleic Acids?

Nucleic acids are biopolymers composed of nucleotide monomers that store, transmit, and express genetic information in all living organisms. First isolated from cell nuclei by Friedrich Miescher in 1869, these macromolecules are the molecular basis of heredity. Two types of nucleic acids exist in nature: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). DNA serves as the long-term repository of genetic information, while RNA acts as the intermediary that converts this stored information into functional proteins. Together, they form the central dogma of molecular biology: DNA is transcribed into RNA, which is translated into protein.

The informational content of nucleic acids resides in their linear sequence of nitrogenous bases. This sequence encodes the instructions for building every protein in an organism, as well as regulatory elements that control when and where those proteins are produced. Understanding nucleic acid structure is therefore foundational to genetics, molecular biology, and biotechnology.

DNA vs. RNA: An Overview

At first glance, DNA and RNA appear similar—both are polymers of nucleotides linked by phosphodiester bonds. However, three fundamental chemical differences distinguish them. First, DNA contains the sugar deoxyribose, while RNA contains ribose; the absence of a hydroxyl group at the 2′ carbon of deoxyribose makes DNA more stable. Second, DNA uses thymine as one of its four bases, whereas RNA uses uracil instead. Third, DNA exists as a double-stranded helix, while RNA is typically single-stranded. These differences have profound consequences for the stability, function, and cellular localization of each molecule. DNA is confined to the nucleus (in eukaryotes) where it is protected, while RNA is synthesized in the nucleus and exported to the cytoplasm to direct protein synthesis.

Chemical Building Blocks: Nucleotides

Phosphate Group and Sugar

Every nucleotide consists of three components: a phosphate group, a five-carbon (pentose) sugar, and a nitrogenous base. The phosphate group is attached to the 5′ carbon of the sugar via a phosphoester bond. In solution at physiological pH, the phosphate group carries a negative charge, making nucleic acids acidic and highly soluble in water. This negative charge also enables nucleic acids to interact with positively charged proteins, such as histones, and to migrate in an electric field during gel electrophoresis.

The sugar distinguishes DNA from RNA. DNA contains 2′-deoxyribose, which has a hydrogen atom at the 2′ carbon instead of a hydroxyl group. RNA contains ribose, which has a hydroxyl group at the 2′ position. This single difference has major consequences: the 2′-hydroxyl in RNA makes the molecule more chemically reactive and prone to hydrolysis, particularly under alkaline conditions. In contrast, DNA's deoxyribose renders it remarkably stable, which is essential for its role as the long-term genetic archive.

Nucleotides are linked together by phosphodiester bonds that connect the 5′ phosphate of one nucleotide to the 3′ hydroxyl of the next. This creates a sugar-phosphate backbone with a distinct polarity: one end has a free 5′ phosphate (the 5′ end) and the other has a free 3′ hydroxyl (the 3′ end). This directionality is critical for all nucleic acid processes, including replication, transcription, and translation. For a deeper look at nucleotide chemistry, see Nucleotide Nucleic Acid.

Nitrogenous Bases: Purines and Pyrimidines

The nitrogenous bases are planar, aromatic heterocyclic molecules that carry the genetic information. They fall into two categories: purines and pyrimidines. Purines are double-ringed structures: adenine (A) and guanine (G). Pyrimidines are single-ringed structures: cytosine (C), thymine (T, found only in DNA), and uracil (U, found only in RNA).

The bases are attached to the 1′ carbon of the sugar via a glycosidic bond. In DNA, adenine pairs with thymine and guanine pairs with cytosine. In RNA, adenine pairs with uracil and guanine pairs with cytosine. The specificity of these pairings arises from hydrogen bonding patterns: A-T (or A-U) forms two hydrogen bonds, while G-C forms three. The additional hydrogen bond in G-C pairs makes GC-rich regions of DNA more stable and resistant to denaturation.

Base stacking also contributes to nucleic acid stability. The planar aromatic rings stack on top of each other within the helix, stabilized by hydrophobic interactions and van der Waals forces. This stacking shields the bases from water and contributes significantly to the overall thermodynamic stability of the double helix.

DNA Structure: The Double Helix

Base Pairing and Hydrogen Bonds

In 1953, James Watson and Francis Crick proposed the double helix model of DNA based on X-ray diffraction data collected by Rosalind Franklin and Maurice Wilkins. The model describes DNA as two antiparallel polynucleotide strands wound around each other in a right-handed helix. The sugar-phosphate backbones form the exterior of the helix, while the nitrogenous bases point inward and pair with complementary bases on the opposite strand.

The base pairing rules are strict: adenine pairs with thymine via two hydrogen bonds, and guanine pairs with cytosine via three hydrogen bonds. This complementarity is the basis of DNA replication—each strand serves as a template for synthesizing a new complementary strand. The specificity of base pairing also underlies many molecular biology techniques, including PCR and DNA sequencing. For a comprehensive treatment of the hydrogen bonding patterns and their thermodynamic consequences, see Base Pairing.

The double helix has a diameter of approximately 2 nm and a pitch of 3.4 nm per complete turn, which contains about 10 base pairs. The major and minor grooves that result from the asymmetric attachment of bases to the sugar-phosphate backbone provide binding sites for proteins. Transcription factors, for example, recognize specific DNA sequences by contacting bases through the major groove.

Antiparallel Strands and 5' to 3' Direction

The two strands of DNA run in opposite directions: one strand runs 5′ to 3′ and the other runs 3′ to 5′. This antiparallel arrangement is essential for base pairing geometry—the hydrogen bonding between A-T and G-C pairs requires that the two glycosidic bonds be oriented in opposite directions. The antiparallel nature also dictates the mechanism of DNA replication, in which the leading strand is synthesized continuously while the lagging strand is synthesized in short Okazaki fragments.

The 5′ to 3′ polarity of nucleic acids is defined by the direction of phosphodiester bond formation. New nucleotides are always added to the 3′ end of a growing strand, a rule that applies to DNA polymerases, RNA polymerases, and reverse transcriptases. This directionality is also exploited in DNA sequencing, where the sequence is read from the 5′ end to the 3′ end.

In cells, DNA does not exist as a naked, linear molecule. It is packaged with proteins into chromatin, which compacts the DNA approximately 10,000-fold to fit within the nucleus. The hierarchical organization of DNA—from the double helix to nucleosomes to higher-order chromatin fibers—is described in detail in Chromatin Structure and Chromosome Structure. Additionally, the double helix can be further twisted into supercoiled structures, particularly in prokaryotes, a topic covered under DNA Supercoiling.

RNA Structure: Single-Stranded and Versatile

Types of RNA

RNA is typically single-stranded, which allows it to fold into complex three-dimensional structures that can perform diverse functions. Three main types of RNA participate in protein synthesis:

Messenger RNA (mRNA) carries the genetic information from DNA to the ribosome. In eukaryotes, mRNA undergoes extensive processing: a 5′ 7-methylguanosine cap is added, a 3′ poly(A) tail of approximately 200 adenine residues is appended, and introns are removed by splicing. These modifications protect the mRNA from degradation and facilitate translation.

Transfer RNA (tRNA) is a small RNA molecule of 70–90 nucleotides that acts as an adaptor between mRNA codons and amino acids. Each tRNA has an anticodon loop that base-pairs with a specific mRNA codon and an acceptor stem where the corresponding amino acid is attached. There are at least 20 different tRNA molecules, one for each amino acid, and many organisms have multiple tRNAs for a single amino acid.

Ribosomal RNA (rRNA) is the catalytic and structural component of ribosomes. In bacteria, the ribosome is composed of three rRNA molecules (23S, 16S, and 5S) and approximately 50 proteins. In eukaryotes, the ribosome contains four rRNA molecules (28S, 18S, 5.8S, and 5S). The 23S rRNA in bacteria is a ribozyme—it catalyzes peptide bond formation during translation.

Beyond these classical types, many non-coding RNAs regulate gene expression. MicroRNAs (miRNAs) are ~22-nucleotide RNAs that silence genes by base-pairing with complementary sequences in target mRNAs, leading to mRNA degradation or translational repression. Small interfering RNAs (siRNAs) participate in a similar pathway, while long non-coding RNAs (lncRNAs) regulate chromatin state and transcription.

Secondary Structures in RNA

Because RNA is single-stranded, it can fold back on itself to form intramolecular base pairs. The most common secondary structure is the stem-loop (or hairpin), which forms when a complementary sequence within the same strand base-pairs, creating a double-stranded stem and an unpaired loop. These structures are ubiquitous in RNA and are essential for function.

tRNA provides a classic example of RNA secondary and tertiary structure. Its cloverleaf secondary structure contains four stems and three loops. The anticodon loop recognizes the mRNA codon, while the TΨC loop and D loop contribute to the L-shaped tertiary structure that fits into the ribosome. The 3D structure is stabilized by modified nucleotides, including pseudouridine (Ψ) and dihydrouridine (D), which alter base-pairing properties and increase structural stability.

Riboswitches are mRNA elements that directly bind small metabolites and undergo conformational changes that regulate gene expression. For example, the purine riboswitch binds guanine or adenine and switches between two alternative secondary structures—one that permits transcription or translation and one that terminates it. This demonstrates that RNA structure is not merely a static scaffold but a dynamic regulatory element.

Functions of DNA and RNA in the Cell

DNA: The Blueprint of Life

DNA's primary function is the long-term storage of genetic information. The sequence of bases along the DNA molecule encodes the amino acid sequences of all proteins, as well as regulatory information that controls gene expression. In humans, the genome comprises approximately 3.2 billion base pairs distributed across 23 chromosome pairs, containing roughly 20,000–25,000 protein-coding genes.

DNA must be replicated faithfully before each cell division. DNA polymerase synthesizes new DNA at a rate of approximately 50 nucleotides per second in eukaryotes, with an error rate of about one mistake per 10⁹ nucleotides incorporated, thanks to proofreading and mismatch repair mechanisms. When DNA is damaged by UV radiation, chemical mutagens, or reactive oxygen species, repair pathways such as Nucleotide Excision Repair remove and replace the damaged bases. The remarkable stability of DNA—conferred by the 2′-deoxyribose sugar and the double-stranded structure—ensures that genetic information is preserved over an organism's lifetime and across generations.

RNA: From Gene to Protein

RNA serves as the intermediary that converts genetic information into proteins. The process begins with transcription, in which RNA polymerase synthesizes a single-stranded RNA molecule complementary to the DNA template. In bacteria, a single RNA polymerase (core enzyme plus sigma factor) initiates transcription at promoter sequences. In eukaryotes, three RNA polymerases exist: RNA polymerase I transcribes rRNA genes, RNA polymerase II transcribes protein-coding genes, and RNA polymerase III transcribes tRNA and 5S rRNA genes.

The resulting primary transcript undergoes processing to become mature mRNA. In eukaryotes, this includes 5′ capping, 3′ polyadenylation, and splicing. Alternative splicing allows a single gene to produce multiple mRNA isoforms, greatly expanding the proteome diversity. It is estimated that over 95% of human multi-exon genes undergo alternative splicing.

Translation then converts the mRNA sequence into a polypeptide chain. This occurs on ribosomes, which are composed of rRNA and proteins. The ribosome reads the mRNA in the 5′ to 3′ direction, decoding each three-nucleotide codon. Transfer RNA molecules bring the corresponding amino acids, and peptide bonds are formed between adjacent amino acids. Translation proceeds at a rate of approximately 5–20 amino acids per second in bacteria and involves three phases: initiation, elongation, and termination.

RNA also regulates gene expression at multiple levels. MicroRNAs and siRNAs silence genes post-transcriptionally, while lncRNAs can recruit chromatin-modifying complexes to specific genomic loci. The versatility of RNA—its ability to store information, catalyze reactions, and regulate gene expression—has led to the hypothesis that RNA preceded DNA and proteins in early evolution, a concept known as the "RNA world" hypothesis.

Key Differences Between DNA and RNA

Sugar: Deoxyribose vs. Ribose

The most fundamental chemical difference between DNA and RNA is the sugar component. DNA contains 2′-deoxyribose, which lacks a hydroxyl group at the 2′ carbon. RNA contains ribose, which has a 2′-hydroxyl group. This difference has several consequences:

1. Chemical stability: The 2′-hydroxyl in RNA makes it susceptible to base-catalyzed hydrolysis. Under alkaline conditions, the 2′-hydroxyl attacks the adjacent phosphodiester bond, cleaving the RNA strand. DNA, lacking this hydroxyl, is resistant to alkaline hydrolysis. This is why DNA can be denatured with sodium hydroxide during Southern blotting, while RNA cannot.

1. Conformation: The 2′-hydroxyl in RNA prevents the RNA double helix from adopting the B-form conformation typical of DNA. RNA helices adopt the A-form, which has a wider, shallower major groove and a narrower, deeper minor groove.

1. Flexibility: The 2′-hydroxyl in RNA allows it to adopt a wider range of conformations, enabling the complex folding required for catalytic and regulatory functions.

Base: Thymine vs. Uracil

DNA uses thymine, while RNA uses uracil. Both bases pair with adenine, but they differ by a single methyl group: thymine is 5-methyluracil. The presence of thymine in DNA provides a mechanism for repairing cytosine deamination. Cytosine can spontaneously deaminate to form uracil. If uracil were a normal DNA base, this damage would go undetected. Because uracil is normally found only in RNA, the DNA repair enzyme uracil-DNA glycosylase recognizes uracil in DNA as damage and removes it, initiating base excision repair. This surveillance system would be impossible if thymine were not the standard DNA base.

Stability and Location

DNA is a highly stable molecule designed for long-term information storage. Its double-stranded structure protects the bases from chemical modification, and the absence of the 2′-hydroxyl prevents hydrolysis. In eukaryotic cells, DNA is confined to the nucleus (and mitochondria/chloroplasts), where it is packaged into chromatin. RNA, in contrast, is relatively short-lived. Most mRNAs have half-lives of minutes to hours, allowing cells to rapidly adjust protein production in response to changing conditions. RNA is synthesized in the nucleus and transported to the cytoplasm, where translation occurs. Some RNAs, such as regulatory lncRNAs, remain in the nucleus to modulate chromatin structure and gene expression.

The following table summarizes the key differences:

Methods Used to Study Nucleic Acids

Gel Electrophoresis and PCR

Gel electrophoresis separates nucleic acids by size and charge. Because the phosphate backbone carries a negative charge, DNA and RNA migrate toward the positive electrode when an electric field is applied. Agarose gels (typically 0.8–2% agarose) are used for DNA fragments ranging from 100 bp to 50 kb, while polyacrylamide gels provide higher resolution for smaller fragments and for RNA. Nucleic acids are visualized with intercalating dyes such as ethidium bromide or SYBR Green, which fluoresce when bound to nucleic acids. The migration distance is inversely proportional to the log of the molecular weight, allowing size determination by comparison with a DNA ladder of known fragment sizes.

Polymerase chain reaction (PCR) amplifies specific DNA sequences exponentially. A typical PCR reaction contains:

• Template DNA (1–100 ng)
• Two sequence-specific primers (0.1–0.5 µM each)
• Deoxynucleotide triphosphates (dNTPs, 200 µM each)
• Thermostable DNA polymerase (e.g., Taq polymerase, 1–2.5 units)
• Buffer with MgCl₂ (1.5–3 mM)

The reaction undergoes 25–40 cycles of three steps: denaturation at 94–98°C for 20–30 seconds, annealing at 50–65°C for 20–40 seconds, and extension at 72°C for 1 minute per kilobase of amplicon. PCR is used for cloning, genotyping, diagnostics, and forensic analysis. Reverse transcription PCR (RT-PCR) converts RNA to cDNA using reverse transcriptase before amplification, enabling the detection and quantification of RNA transcripts.

DNA Sequencing and Structural Analysis

DNA sequencing determines the exact order of nucleotides in a DNA molecule. Sanger sequencing, developed by Frederick Sanger in 1977, uses chain-terminating dideoxynucleotides that lack a 3′-hydroxyl group. When incorporated into a growing strand, they prevent further extension, producing a set of fragments of varying lengths that are separated by capillary electrophoresis. Modern high-throughput sequencing (next-generation sequencing) methods parallelize this process, generating millions of reads simultaneously. The Illumina platform, for example, uses reversible fluorescently labeled terminators and bridge amplification to sequence clusters of identical DNA fragments.

X-ray crystallography has been instrumental in determining nucleic acid structure. Rosalind Franklin's X-ray diffraction images of DNA fibers provided the key evidence for the double helix. Today, X-ray crystallography of DNA-protein complexes, ribosomes, and RNA enzymes has revealed atomic-level details of nucleic acid structure and function. Cryo-electron microscopy (cryo-EM) has emerged as a powerful alternative for large complexes that resist crystallization, such as the eukaryotic ribosome and spliceosome. Nuclear magnetic resonance (NMR) spectroscopy complements these methods by providing dynamic information about nucleic acid structure in solution.

Common Misconceptions and Pitfalls

Base Pairing Mistakes

A frequent error among students is confusing the base pairing rules between DNA and RNA. In DNA, adenine pairs with thymine (A-T) and guanine pairs with cytosine (G-C). In RNA, adenine pairs with uracil (A-U) and guanine pairs with cytosine (G-C). A common mistake is writing A-T base pairs in RNA or A-U base pairs in DNA. Remember: thymine is exclusive to DNA, and uracil is exclusive to RNA.

Another common error is misidentifying which bases are purines and which are pyrimidines. Adenine and guanine are purines (double-ringed). Cytosine, thymine, and uracil are pyrimidines (single-ringed). A helpful mnemonic: "CUT the py" (Cytosine, Uracil, Thymine are pyrimidines).

Students also frequently forget that G-C pairs have three hydrogen bonds while A-T (or A-U) pairs have two. This difference explains why GC-rich DNA has a higher melting temperature (Tm). The Tm of a DNA duplex can be estimated by the formula: Tm = 4(G+C) + 2(A+T) for short oligonucleotides, or more accurately by the nearest-neighbor method.

Overlooking RNA's Complexity

Many students assume RNA is simply a "lesser" version of DNA—single-stranded, less stable, and only involved in protein synthesis. This view overlooks the remarkable functional diversity of RNA. RNA can fold into complex three-dimensional structures that catalyze chemical reactions (ribozymes), regulate gene expression (riboswitches, miRNAs), and guide RNA modifications (snoRNAs). The ribosome itself is a ribozyme: the peptidyl transferase activity resides in the 23S rRNA, not in ribosomal proteins.

Another misconception is that RNA is always single-stranded. While most cellular RNAs are single-stranded, many viruses have double-stranded RNA genomes (e.g., reoviruses). Additionally, RNA can form double-stranded regions through intramolecular base pairing, as seen in stem-loops, and through intermolecular interactions, as in miRNA-mRNA duplexes. The A-form helix adopted by double-stranded RNA is distinct from the B-form of DNA, with a narrower major groove and a wider minor groove.

Students also often confuse the directionality of nucleic acid synthesis. Both DNA and RNA are synthesized in the 5′ to 3′ direction, meaning nucleotides are added to the 3′ end of the growing strand. The template strand, however, is read in the 3′ to 5′ direction. This is a common source of confusion when drawing replication forks or transcription bubbles.

Practical Summary: Mastering Nucleic Acid Basics

Key Takeaways

1. Nucleic acids are polymers of nucleotides, each consisting of a phosphate group, a pentose sugar, and a nitrogenous base. The sugar (deoxyribose in DNA, ribose in RNA) and the bases (thymine in DNA, uracil in RNA) distinguish the two types.

1. DNA is a double-stranded, antiparallel helix held together by hydrogen bonds between complementary bases (A-T and G-C). The sugar-phosphate backbone runs 5′ to 3′ on one strand and 3′ to 5′ on the other.

1. RNA is typically single-stranded but can fold into complex secondary and tertiary structures. It exists in multiple forms—mRNA, tRNA, rRNA, and various regulatory RNAs—each with specific functions.

1. DNA stores genetic information; RNA expresses it. Transcription converts DNA to RNA, and translation converts RNA to protein. This flow of information is the central dogma of molecular biology.

1. The 2′-hydroxyl group in RNA makes it less stable than DNA, which lacks this group. DNA's stability suits its role as the long-term genetic archive, while RNA's instability allows rapid regulation of gene expression.

1. Base pairing is specific and predictable: A pairs with T (or U), and G pairs with C. The number of hydrogen bonds (2 for A-T, 3 for G-C) affects nucleic acid stability.

1. Nucleic acids can be studied by multiple techniques, including gel electrophoresis, PCR, DNA sequencing, and X-ray crystallography, each providing different types of structural or functional information.

Study Tips

When studying nucleic acids, focus on the relationship between structure and function. Ask yourself: Why does DNA use thymine instead of uracil? (Answer: to detect cytosine deamination.) Why does RNA use ribose instead of deoxyribose? (Answer: the 2′-hydroxyl enables catalytic activity and complex folding.) Why is DNA double-stranded? (Answer: to provide a template for repair and replication.)

Practice drawing the structures of nucleotides and the base pairing rules until they become second nature. Use flashcards to memorize which bases are purines and which are pyrimidines, and which bases pair with which. When studying transcription and translation, trace the directionality of synthesis and the roles of each RNA type.

Finally, connect the concepts to real-world applications. PCR relies on the specificity of base pairing and the stability of DNA. RNA interference uses double-stranded RNA to silence genes. CRISPR-Cas9 uses guide RNA to direct DNA cleavage. Understanding the fundamental chemistry of nucleic acids will help you grasp these advanced technologies.

Frequently Asked Questions

Is DNA and RNA nucleic acids?

Yes. DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) are the two types of nucleic acids found in living organisms. They are polymers of nucleotides and are responsible for storing, transmitting, and expressing genetic information. Nucleic acids are one of the four major classes of biological macromolecules, alongside proteins, carbohydrates, and lipids.

Why are DNA and RNA nucleic acids?

DNA and RNA are classified as nucleic acids because they are composed of nucleotide monomers linked by phosphodiester bonds. The term "nucleic acid" reflects their discovery in the nucleus (nucle-) and their acidic nature (-ic acid), which results from the negatively charged phosphate groups in their backbone. The phosphate groups ionize at physiological pH, giving nucleic acids their acidic properties.

What is the function of DNA and RNA in nucleic acid?

DNA functions as the long-term storage molecule for genetic information. It contains the instructions for building all proteins and regulatory elements that control gene expression. RNA functions as the intermediary that expresses this information: mRNA carries the genetic message from DNA to ribosomes, tRNA delivers amino acids during translation, and rRNA catalyzes peptide bond formation. RNA also regulates gene expression through mechanisms such as RNA interference and riboswitches.

What are the main structural differences between DNA and RNA?

The main structural differences are: (1) the sugar—DNA contains 2′-deoxyribose, while RNA contains ribose; (2) the pyrimidine base—DNA uses thymine, while RNA uses uracil; (3) the strand structure—DNA is typically double-stranded and antiparallel, while RNA is typically single-stranded; and (4) the helix conformation—DNA adopts the B-form helix, while double-stranded RNA adopts the A-form. These differences affect stability, flexibility, and function.

How do DNA and RNA base pairing differ?

In DNA, adenine pairs with thymine (A-T) and guanine pairs with cytosine (G-C). In RNA, adenine pairs with uracil (A-U) and guanine pairs with cytosine (G-C). The A-T pair forms two hydrogen bonds, while the G-C pair forms three. During transcription, the RNA polymerase reads the DNA template strand and incorporates the complementary RNA nucleotide: a DNA adenine specifies an RNA uracil, a DNA thymine specifies an RNA adenine, a DNA guanine specifies an RNA cytosine, and a DNA cytosine specifies an RNA guanine.

Are there any exceptions to RNA being single-stranded?

Yes. While most cellular RNAs are single-stranded, several exceptions exist. Many viruses have double-stranded RNA genomes, including reoviruses and rotaviruses. Additionally, single-stranded RNA molecules frequently form double-stranded regions through intramolecular base pairing, creating stem-loop structures. MicroRNAs and siRNAs function as double-stranded RNA duplexes during RNA interference. Transfer RNA and ribosomal RNA also contain extensive double-stranded regions within their folded structures.

Key Takeaways

• Nucleic acids are linear polymers of nucleotides, each composed of a phosphate group, a pentose sugar, and a nitrogenous base; DNA uses deoxyribose and thymine, while RNA uses ribose and uracil.
• DNA exists as a double-stranded, antiparallel helix with complementary base pairing (A-T, G-C) held together by hydrogen bonds, with the sugar-phosphate backbone running 5′ to 3′ on each strand.
• RNA is typically single-stranded but folds into complex structures such as stem-loops, and exists in multiple functional forms including mRNA, tRNA, rRNA, and regulatory RNAs.
• DNA serves as the stable, long-term repository of genetic information, while RNA mediates gene expression through transcription and translation, and also performs regulatory and catalytic functions.
• The 2′-hydroxyl group in RNA makes it chemically less stable than DNA, which is essential for DNA's role as the durable genetic archive and enables RNA's structural and functional versatility.
• Base pairing rules are strict and predictable: A pairs with T (or U) via two hydrogen bonds, and G pairs with C via three hydrogen bonds; these rules underlie replication, transcription, and all nucleic acid-based technologies.
• Nucleic acids are studied using techniques such as gel electrophoresis, PCR, DNA sequencing, and X-ray crystallography, each revealing different aspects of their structure and function.

Further Reading

• Di Caro V, Giannoukakis N, Trucco M. In vivo delivery of nucleic acid-formulated microparticles as a potential tolerogenic vaccine for type 1 diabetes. The review of diabetic studies : RDS. 2012. PubMed 23804272
• Cerles A, Dingus-Simmons A, Casagrande R. A risk-based framework to guide oversight of nucleic acid constructs. Frontiers in bioengineering and biotechnology. 2026. PubMed 42528926
• Shioda T, Iwasaki K, Shibuta H. Determination of the complete nucleotide sequence of the Sendai virus genome RNA and the predicted amino acid sequences of the F, HN and L proteins. Nucleic acids research. 1986. PubMed 3005975
• Mullegama SV et al. Nucleic Acid Extraction from Human Biological Samples. Methods in molecular biology (Clifton, N.J.). 2019. PubMed 30539458
• Okamoto A. DNA/RNA Fluorescence Imaging by Synthetic Nucleic Acids. Advances in experimental medicine and biology. 2021. PubMed 33834446
• Berdis A. Reimagining the Power of Nucleic Acids as Therapeutic and Diagnostic Agents. Biomolecules. 2021. PubMed 34827705

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