3.4 Nucleic acids: structure and function
3 min read•july 22, 2024
Nucleic acids are the building blocks of life, storing and transmitting genetic information. and , composed of nucleotides, play crucial roles in cellular processes. DNA's structure and RNA's versatility enable the flow of genetic information.
Various types of RNA perform specific functions in cells. carries genetic instructions, delivers amino acids, and forms ribosomes. Together, these molecules orchestrate the complex process of protein synthesis, translating genetic code into functional proteins.
Nucleic Acid Building Blocks and Structure
Components of nucleic acids
Top images from around the web for Components of nucleic acids
The Structure of DNA | OpenStax: Concepts of Biology View original
Is this image relevant?
Nucleic Acids – Principles of Biology View original
Is this image relevant?
DNA Structure and Function | Biology I Laboratory Manual View original
Is this image relevant?
The Structure of DNA | OpenStax: Concepts of Biology View original
Is this image relevant?
Nucleic Acids – Principles of Biology View original
Is this image relevant?
1 of 3
Top images from around the web for Components of nucleic acids
The Structure of DNA | OpenStax: Concepts of Biology View original
Is this image relevant?
Nucleic Acids – Principles of Biology View original
Is this image relevant?
DNA Structure and Function | Biology I Laboratory Manual View original
Is this image relevant?
The Structure of DNA | OpenStax: Concepts of Biology View original
Is this image relevant?
Nucleic Acids – Principles of Biology View original
Is this image relevant?
1 of 3
- Nucleotides serve as the fundamental building blocks of nucleic acids
- Each is composed of three essential components:
- Sugar (pentose) varies between DNA and RNA
- DNA contains deoxyribose sugar (lacks an oxygen atom at the 2' position)
- RNA contains ribose sugar
- Phosphate group attached to the 5' carbon of the sugar
- Nitrogenous base linked to the 1' carbon of the sugar
- Purines: Adenine (A) and Guanine (G) have a double-ring structure
- Pyrimidines: Cytosine (C), Thymine (T) in DNA, and Uracil (U) in RNA have a single-ring structure
- Sugar (pentose) varies between DNA and RNA
- Each is composed of three essential components:
DNA vs RNA
- DNA (Deoxyribonucleic acid) is a double-stranded molecule
- Forms a double helix structure stabilized by hydrogen bonds between complementary base pairs
- Sugar component is deoxyribose
- Nitrogenous bases: Adenine (A), Thymine (T), Guanine (G), and Cytosine (C)
- Serves as the primary storage molecule for genetic information in cells
- RNA (Ribonucleic acid) is typically single-stranded
- Can form secondary structures through base pairing within the same strand
- Sugar component is ribose
- Nitrogenous bases: Adenine (A), Uracil (U), Guanine (G), and Cytosine (C)
- Participates in various cellular processes (protein synthesis, gene regulation)
Structure of DNA
- DNA is composed of two antiparallel polynucleotide strands coiled around a central axis
- Strands are held together by hydrogen bonds formed between complementary base pairs
- Adenine (A) always pairs with Thymine (T) via two hydrogen bonds
- Guanine (G) always pairs with Cytosine (C) via three hydrogen bonds
- The double helix is right-handed, with approximately 10 base pairs per turn
- Strands are held together by hydrogen bonds formed between complementary base pairs
- The is located on the exterior of the helix
- Phosphodiester bonds connect the 3' carbon of one nucleotide to the 5' carbon of the next
- Nitrogenous bases are positioned on the interior of the helix, stacked perpendicular to the axis
Nucleic Acid Function and Types of RNA
Nucleic acids in genetic information
- DNA functions as the primary storage molecule for genetic information in cells
- Genes are specific DNA sequences that encode instructions for synthesizing proteins and other cellular components
- During cell division (mitosis or meiosis), DNA is replicated and distributed to daughter cells
- Ensures the faithful transmission of genetic information across generations
- RNA acts as an intermediary in the flow of genetic information from DNA to proteins
- Genes are transcribed into RNA molecules, which are then translated into proteins
Functions of RNA types
- Messenger RNA (mRNA) serves as a template for protein synthesis
- Produced during , where the DNA sequence of a gene is used as a template
- Carries genetic information from the nucleus to ribosomes in the cytoplasm
- Each three-nucleotide sequence () in mRNA specifies a particular amino acid
- Transfer RNA (tRNA) molecules act as adapters in the of genetic code into amino acids
- Each tRNA has an that recognizes a specific mRNA codon
- The corresponding amino acid is attached to the tRNA by aminoacyl-tRNA synthetases
- tRNAs transport amino acids to the ribosome and ensure proper alignment with mRNA during protein synthesis
- Ribosomal RNA (rRNA) is a crucial structural and catalytic component of ribosomes
- Ribosomes are the sites of protein synthesis in cells
- rRNA catalyzes the formation of peptide bonds between amino acids during translation
- Ensures the accurate alignment of mRNA and tRNA molecules for proper protein assembly
Key Terms to Review (24)
Anticodon: An anticodon is a sequence of three nucleotides located on a tRNA molecule that is complementary to a specific codon on mRNA. This complementary pairing is crucial for the accurate translation of genetic information into proteins, linking the mRNA sequence to the appropriate amino acid during protein synthesis.
Chromatin: Chromatin is a complex of DNA and proteins found in the nucleus of eukaryotic cells, responsible for packaging the long strands of DNA into a more compact, organized structure. This organization is crucial for DNA replication, gene expression, and maintaining the integrity of the genetic material. Chromatin exists in two forms: euchromatin, which is less condensed and active in transcription, and heterochromatin, which is more condensed and typically inactive.
Codon: A codon is a sequence of three nucleotides in DNA or RNA that corresponds to a specific amino acid or a stop signal during protein synthesis. This triplet code is essential for translating genetic information into proteins, as each codon matches with a corresponding tRNA molecule that carries the appropriate amino acid. The codon sequence ultimately determines the primary structure of proteins, which is vital for their function in cellular processes.
Deletion: Deletion refers to a genetic mutation involving the loss of a segment of DNA from a chromosome, which can affect the structure and function of nucleic acids. This alteration can lead to significant changes in gene expression and protein synthesis, potentially resulting in various genetic disorders or diseases. Understanding deletions is crucial in the study of molecular biology, genetics, and their implications for health and disease.
DNA: DNA, or deoxyribonucleic acid, is a molecule that carries the genetic instructions essential for the growth, development, functioning, and reproduction of all living organisms. It is structured as a double helix, composed of two long strands of nucleotides running in opposite directions, which allows it to store and transmit biological information. The specific sequence of nucleotides within DNA encodes the instructions for building proteins, making it fundamental to cellular function and heredity.
DNA polymerase: DNA polymerase is an enzyme that synthesizes new strands of DNA by adding nucleotides to a pre-existing DNA template strand during the processes of DNA replication and repair. This enzyme plays a crucial role in ensuring the accuracy and efficiency of genetic information transmission, connecting it to how nucleic acids function structurally and functionally, as well as their involvement in various cellular processes such as DNA repair mechanisms and molecular biology techniques used in research.
Double helix: The double helix is the molecular structure of DNA, consisting of two long strands that spiral around each other, resembling a twisted ladder. This unique shape is crucial for the stability and function of DNA, allowing it to store genetic information and facilitate processes such as replication and transcription.
Enhancer: An enhancer is a regulatory DNA sequence that can significantly increase the transcription of a gene, often located far from the promoter it influences. Enhancers contain binding sites for transcription factors, which, when activated, can interact with the transcription machinery to boost gene expression. This makes enhancers crucial players in controlling when and where genes are expressed in an organism.
Gene expression: Gene expression is the process by which information from a gene is used to synthesize a functional gene product, typically proteins, which ultimately influence the phenotype of an organism. This process involves several key steps including transcription of DNA into messenger RNA (mRNA) and translation of mRNA into proteins, influenced by various signaling pathways and cellular mechanisms.
Insertion: Insertion refers to the addition of one or more nucleotide bases into a DNA or RNA sequence. This alteration can lead to changes in the reading frame during translation, affecting protein synthesis and function. Understanding insertion is crucial as it can result in mutations that may have significant implications for an organism's biology.
Ligase: Ligase is an enzyme that facilitates the joining of two DNA strands by catalyzing the formation of a phosphodiester bond. This process is crucial during DNA replication and repair, ensuring the integrity and continuity of the genetic material. Ligase plays a vital role in connecting Okazaki fragments on the lagging strand during replication, as well as in various recombinant DNA techniques.
MRNA: mRNA, or messenger RNA, is a single-stranded nucleic acid that serves as the template for protein synthesis. It is transcribed from DNA and carries the genetic information from the nucleus to the ribosomes, where proteins are made. The structure of mRNA, including its sequence and modifications, plays a critical role in determining how proteins are produced in cells.
Nucleotide: A nucleotide is the basic building block of nucleic acids, consisting of three components: a nitrogenous base, a five-carbon sugar, and a phosphate group. Nucleotides play a crucial role in the structure and function of DNA and RNA, serving as the monomers that link together to form long chains known as polynucleotides. They are essential for storing and transmitting genetic information within cells, making them key players in biological processes.
Point Mutation: A point mutation is a change in a single nucleotide base pair in the DNA sequence, which can lead to alterations in gene function. This type of mutation can have varying effects on protein synthesis, ranging from no effect at all to causing significant changes in the resulting protein. Understanding point mutations is crucial as they play a key role in genetic diversity, disease development, and the overall functionality of nucleic acids.
Promoter: A promoter is a specific DNA sequence located upstream of a gene that serves as the binding site for RNA polymerase and other transcription factors to initiate transcription. Promoters are crucial for controlling the expression of genes, influencing when and how much a gene is expressed in both prokaryotic and eukaryotic cells.
Replication: Replication is the process by which a cell duplicates its DNA, ensuring that each daughter cell receives an identical set of genetic information. This process is crucial for cell division and is tightly regulated to maintain genetic stability, allowing organisms to grow, develop, and repair tissues. It involves several key enzymes and proteins that work together to unwind the DNA helix, synthesize new strands, and ensure accurate copying of the genetic material.
RNA: RNA, or ribonucleic acid, is a crucial molecule found in all living cells that plays a vital role in coding, decoding, regulation, and expression of genes. Unlike DNA, RNA is typically single-stranded and contains the sugar ribose, along with the nitrogenous bases adenine, guanine, cytosine, and uracil. This unique structure allows RNA to perform various functions in the cell, including serving as a template for protein synthesis and acting as a messenger carrying genetic information from DNA to ribosomes.
RNA polymerase: RNA polymerase is an essential enzyme responsible for synthesizing RNA from a DNA template during the process of transcription. This enzyme plays a critical role in the expression of genes, converting the genetic code into functional RNA molecules that carry out various functions in the cell.
RRNA: rRNA, or ribosomal RNA, is a type of RNA that plays a crucial role in the synthesis of proteins by forming the core of ribosome structures and catalyzing the translation process. It serves as a structural and functional component of ribosomes, which are the cellular machinery responsible for translating messenger RNA (mRNA) into proteins. This connection to protein synthesis highlights its essential function in gene expression and cellular activity.
Silencer: A silencer is a regulatory DNA element that functions to inhibit the transcription of specific genes, effectively reducing or preventing the expression of those genes. Silencers can be found in various locations within the genome and are essential for the precise control of gene expression, ensuring that genes are turned on or off at the right times in response to cellular signals.
Sugar-phosphate backbone: The sugar-phosphate backbone is the structural framework of nucleic acids, such as DNA and RNA, consisting of alternating sugar and phosphate groups. This backbone provides stability and integrity to the nucleic acid structure while allowing for the attachment of nitrogenous bases that carry genetic information.
Transcription: Transcription is the process by which the genetic information encoded in DNA is copied into messenger RNA (mRNA) to be used in protein synthesis. This process connects the genetic blueprint stored in the DNA with the functional roles of proteins, facilitating the flow of genetic information within a cell. Understanding transcription is crucial as it occurs within the nucleus, involves specific DNA sequences, and varies between prokaryotic and eukaryotic organisms.
Translation: Translation is the biological process through which ribosomes synthesize proteins by decoding messenger RNA (mRNA) sequences into polypeptide chains. This process connects nucleic acids and proteins, showcasing how genetic information is expressed and utilized within a cell. It plays a crucial role in determining the structure and function of proteins, relying on the genetic code carried by mRNA and the activity of transfer RNA (tRNA) to facilitate the assembly of amino acids in the correct order.
TRNA: tRNA, or transfer RNA, is a crucial type of RNA that plays a central role in translating genetic information from mRNA into proteins. It serves as an adaptor molecule, matching specific amino acids to their corresponding codons on the mRNA strand during protein synthesis. This function is vital for the accurate assembly of proteins, as each tRNA carries a unique amino acid and has an anticodon that pairs with the codon on mRNA, ensuring that the genetic code is translated correctly.