Nucleotides and Nucleic Acids Quiz
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Nucleotides and Nucleic Acids Quiz

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Questions and Answers

Which type of bond primarily facilitates base pairing in DNA?

  • Hydrogen bonds (correct)
  • Covalent bonds
  • Ionic bonds
  • Metallic bonds

    • What is the most stable form of DNA found under physiological conditions?

  • C form
  • A form
  • Z form
  • B form (correct)

    • Which structural feature is essential for the stability of DNA?

  • Metal ions neutralizing negative charges (correct)
  • Length of the DNA strands
  • Number of base pairs
  • Presence of hydrogen bonds

    • What type of RNA carries genetic information from DNA to ribosomes?

    <p>mRNA</p> Signup and view all the answers

    What contributes to the stability of RNA's secondary structure?

    <p>Base stacking interactions</p> Signup and view all the answers

    Which type of RNA is involved in amino acid binding and translation?

    <p>tRNA</p> Signup and view all the answers

    What structural feature occurs in DNA when there are inverted and repeated sequences?

    <p>Palindromes</p> Signup and view all the answers

    Which form of DNA is characterized by a left-handed helix and a zigzag appearance?

    <p>Z form</p> Signup and view all the answers

    In which type of mRNA do multiple polypeptides get encoded?

    <p>Polycistronic mRNA</p> Signup and view all the answers

    What interaction primarily stabilizes the phosphate backbone in DNA?

    <p>Hydrophilic interactions with water</p> Signup and view all the answers

    What primarily serves as a storehouse of biological information?

    <p>DNA</p> Signup and view all the answers

    Which type of RNA is responsible for carrying the code for protein synthesis?

    <p>Messenger RNA (mRNA)</p> Signup and view all the answers

    What distinguishes DNA from RNA at the 2' position of the pentose sugar?

    <p>Presence of a hydroxyl group</p> Signup and view all the answers

    Which bond connects nucleotides in DNA and RNA?

    <p>Phosphodiester bond</p> Signup and view all the answers

    What are the pyrimidines found in DNA?

    <p>Cytosine and Thymine</p> Signup and view all the answers

    What is the primary structure of nucleic acids?

    <p>Nucleotide sequence and covalent bonds</p> Signup and view all the answers

    Which type of RNA serves as an adapter molecule that binds to amino acids?

    <p>Transfer RNA (tRNA)</p> Signup and view all the answers

    What is one of the functions of non-coding RNA?

    <p>Splicing mRNA</p> Signup and view all the answers

    Which nitrogenous bases are classified as purines?

    <p>Adenine and Guanine</p> Signup and view all the answers

    What structural model describes DNA as a double helix?

    <p>Watson-Crick model</p> Signup and view all the answers

    What is the primary function of DNA?

    <p>Storage and transmission of biological information</p> Signup and view all the answers

    Which of the following is NOT a component of a nucleotide?

    <p>Fatty acid</p> Signup and view all the answers

    Which type of RNA is an intermediate in the transfer of genetic information from DNA to protein?

    <p>Messenger RNA</p> Signup and view all the answers

    What distinguishes ribose in RNA from deoxyribose in DNA?

    <p>Presence of a hydroxyl group at the 2' position</p> Signup and view all the answers

    Which statement about the hydrolysis of nucleic acids is true?

    <p>DNA is more resistant to hydrolysis than RNA.</p> Signup and view all the answers

    Which type of RNA is responsible for assembling amino acids during protein synthesis?

    <p>Transfer RNA</p> Signup and view all the answers

    What is the primary role of cyclic AMP (cAMP) in cells?

    <p>Signal transduction</p> Signup and view all the answers

    Which of the following best describes a nucleoside?

    <p>A nitrogenous base and a pentose sugar</p> Signup and view all the answers

    What connects nucleotides in the backbone of nucleic acids?

    <p>Phosphodiester bonds</p> Signup and view all the answers

    Which class of RNA has the role of forming the structural components of ribosomes?

    <p>Ribosomal RNA</p> Signup and view all the answers

    What characterizes the secondary structure of nucleic acids?

    <p>It consists of stable, regular formations like helices.</p> Signup and view all the answers

    How are the strands of DNA oriented in relation to each other?

    <p>One strand runs from 5' to 3' and the other from 3' to 5'.</p> Signup and view all the answers

    Which statement about base pairing in nucleic acids is true?

    <p>Adenine pairs with thymine or uracil, and guanine pairs with cytosine.</p> Signup and view all the answers

    Which form of RNA typically features secondary structures such as hairpins and loops?

    <p>Transfer RNA (tRNA)</p> Signup and view all the answers

    What role do metal ions, particularly magnesium (Mg2+), play in nucleic acid structure?

    <p>They shield the negative charges of the phosphate backbone.</p> Signup and view all the answers

    Which of the following accurately describes a characteristic of GC-rich DNA?

    <p>It exhibits higher stability due to strong hydrogen bonding.</p> Signup and view all the answers

    What is the primary feature that distinguishes B-form DNA from other forms?

    <p>It is most stable under physiological conditions.</p> Signup and view all the answers

    Which sequence characteristic allows for specific DNA cleavage by restriction enzymes?

    <p>Palindromic sequences</p> Signup and view all the answers

    During DNA replication, each new DNA molecule contains what type of strands?

    <p>One parent strand and one new daughter strand.</p> Signup and view all the answers

    How is UV absorbance useful for quantifying nucleic acids?

    <p>Nucleic acids have strong absorbance at 260 nanometers.</p> Signup and view all the answers

    What is the main reason that GC pairs contribute to increased stability in DNA compared to AT pairs?

    <p>GC pairs have a larger number of hydrogen bonds.</p> Signup and view all the answers

    Which structural feature of DNA is critical for replication and repair processes?

    <p>Antiparallel orientation of the strands.</p> Signup and view all the answers

    What factor significantly affects the solubility of nucleotides in physiological conditions?

    <p>pH levels of the solution.</p> Signup and view all the answers

    How do hairpin structures in RNA form?

    <p>From complementary base pairing within a single strand.</p> Signup and view all the answers

    Which feature is characteristic of Z-form DNA?

    <p>Presence of a left-handed helix configuration.</p> Signup and view all the answers

    What is a primary role of the major and minor grooves of DNA?

    <p>Providing binding sites for proteins and enzymes.</p> Signup and view all the answers

    Why do nucleotides absorb UV light at a specific wavelength of 260 nm?

    <p>Linked to the chemical structure of the bases.</p> Signup and view all the answers

    What secondary structure is most commonly found in tRNA?

    <p>Hairpin loops.</p> Signup and view all the answers

    What describes the role of Hoogstein pairing in nucleic acids?

    <p>It is an alternative interaction for protein binding.</p> Signup and view all the answers

    What defines the B-form of DNA?

    <p>It being the most common form under physiological conditions.</p> Signup and view all the answers

    What are the three components of a nucleotide?

    <p>A nitrogenous base, a pentose sugar, and at least one phosphate group</p> Signup and view all the answers

    Which type of nucleic acid is responsible for storing biological information?

    <p>Deoxyribonucleic acid (DNA)</p> Signup and view all the answers

    What distinguishes ribose from deoxyribose?

    <p>Presence of a hydroxyl group at the 2' position</p> Signup and view all the answers

    Which of the following is NOT a type of RNA?

    <p>Deoxyribose RNA (dRNA)</p> Signup and view all the answers

    What type of bond links nucleotides together in nucleic acids?

    <p>Phosphodiester bonds</p> Signup and view all the answers

    Which nitrogenous base is found only in RNA?

    <p>Uracil</p> Signup and view all the answers

    What is a gene primarily responsible for?

    <p>Producing functional biological products</p> Signup and view all the answers

    What is the primary structure of nucleic acids defined by?

    <p>The sequence of nucleotides and covalent bonds</p> Signup and view all the answers

    What role does non-coding RNA play in the cell?

    <p>Involves in various cellular processes including splicing and regulation</p> Signup and view all the answers

    Which of the following statements about DNA is TRUE?

    <p>DNA has a double helix structure</p> Signup and view all the answers

    What distinguishes the structural component of RNA from DNA?

    <p>Presence of ribose instead of deoxyribose</p> Signup and view all the answers

    Which type of RNA is primarily involved in regulating gene expression?

    <p>Non-coding RNA (ncRNA)</p> Signup and view all the answers

    What is the significance of the 2' hydroxyl group in RNA?

    <p>It acts as a nucleophile, increasing susceptibility to hydrolysis</p> Signup and view all the answers

    What role do phosphodiester bonds play in nucleic acids?

    <p>They link nucleotides together in nucleic acid chains</p> Signup and view all the answers

    Which molecule acts as an adapter during protein synthesis by linking amino acids to mRNA?

    <p>Transfer RNA (tRNA)</p> Signup and view all the answers

    What defines the primary structure of nucleic acids?

    <p>The sequence of nucleotides and their covalent bonds</p> Signup and view all the answers

    What is the correct mechanism by which DNA achieves stability besides hydrogen bonding?

    <p>Base stacking interactions and interactions with metal ions</p> Signup and view all the answers

    In DNA, what base pairs specifically with adenine?

    <p>Thymine</p> Signup and view all the answers

    Which feature differentiates RNA secondary structures from DNA structures?

    <p>RNA can form complex structures with loops and bulges</p> Signup and view all the answers

    Which of the following accurately describes the secondary structure of nucleic acids?

    <p>Characterized by the double-helical arrangement of DNA</p> Signup and view all the answers

    Which statement about the various forms of DNA is true?

    <p>B-form DNA is the most stable under physiological conditions</p> Signup and view all the answers

    What type of interaction holds the two polynucleotide strands of DNA together?

    <p>Hydrogen bonds between complementary base pairs</p> Signup and view all the answers

    What is one critical feature of the tertiary structure of DNA?

    <p>Supercoiling and looping of DNA molecules</p> Signup and view all the answers

    What type of structural alteration in DNA can palindromes cause?

    <p>Distortion in the DNA helix</p> Signup and view all the answers

    Which characteristic is specific to tRNA compared to other types of RNA?

    <p>tRNA possesses complementary regions for base pairing</p> Signup and view all the answers

    Which assertion about hairpins is accurate?

    <p>Hairpins result from complementary regions pairing within the same strand</p> Signup and view all the answers

    What do mirror repeats in DNA sequences typically lead to?

    <p>Alterations in secondary structures</p> Signup and view all the answers

    What phenomenon is caused by the interaction of two hairpins in DNA?

    <p>Creation of cruciform structures</p> Signup and view all the answers

    Which metal ion is most significant for the stability of nucleic acids?

    <p>Magnesium (Mg2+)</p> Signup and view all the answers

    Which of the following best describes the technique used during DNA replication?

    <p>Separating both parent strands to form two daughter strands</p> Signup and view all the answers

    Which nucleotide is exclusively found in RNA?

    <p>Uracil</p> Signup and view all the answers

    What is the primary function of ribosomal RNA (rRNA)?

    <p>Compose the structural framework of ribosomes</p> Signup and view all the answers

    Which component is NOT part of a nucleotide?

    <p>Hydroxyl group</p> Signup and view all the answers

    Which type of nucleotide serves as an important signaling molecule?

    <p>Cyclic AMP</p> Signup and view all the answers

    What distinguishes ribonucleotides from deoxyribonucleotides?

    <p>Presence of a hydroxyl group at the 2' position</p> Signup and view all the answers

    In which type of RNA does splicing occur?

    <p>Non-coding RNA</p> Signup and view all the answers

    What type of bond connects nucleotides within a nucleic acid polymer?

    <p>Phosphodiester bond</p> Signup and view all the answers

    Which property of nucleotides is primarily utilized to quantify nucleic acid concentrations?

    <p>UV light absorption</p> Signup and view all the answers

    What primarily affects the stability of RNA compared to DNA?

    <p>2' hydroxyl group susceptibility</p> Signup and view all the answers

    Which of the following describes a nucleoside?

    <p>Nitrogenous base and pentose sugar only, without phosphate group</p> Signup and view all the answers

    What is the significance of the antiparallel orientation of DNA strands?

    <p>It allows for accurate base pairing during replication.</p> Signup and view all the answers

    Which form of DNA is primarily recognized in physiological conditions?

    <p>B form</p> Signup and view all the answers

    What do hairpins and cruciforms have in common in terms of DNA structure?

    <p>They both originate from sequences with palindromic characteristics.</p> Signup and view all the answers

    Which of the following accurately describes base stacking interactions in nucleic acids?

    <p>They are mainly due to van der Waals forces between aromatic bases.</p> Signup and view all the answers

    How does the presence of metal ions, such as magnesium (Mg2+), affect nucleic acids?

    <p>They shield the negative charges of the phosphate backbone.</p> Signup and view all the answers

    Which characteristic differentiates the A form of DNA from the B form?

    <p>The A form is wider and forms in low water conditions.</p> Signup and view all the answers

    In RNA, what structural feature allows it to achieve a more complex secondary structure than DNA?

    <p>The ability to fold back upon itself.</p> Signup and view all the answers

    What distinguishes GC base pairs from AT base pairs in terms of stability?

    <p>GC pairs have more hydrogen bonds.</p> Signup and view all the answers

    Which statement about mRNA is correct?

    <p>It can base pair with DNA or tRNA.</p> Signup and view all the answers

    What are palindromes in the context of DNA sequences?

    <p>Sequences that are inverted and repeated.</p> Signup and view all the answers

    What is the role of DNA replication in cell division?

    <p>To ensure each daughter cell receives identical genetic material.</p> Signup and view all the answers

    Which enzyme is primarily responsible for unzipping the DNA double helix during replication?

    <p>Helicase</p> Signup and view all the answers

    During which phase of the cell cycle does DNA replication occur?

    <p>S phase</p> Signup and view all the answers

    What is the function of the primer in DNA replication?

    <p>To provide a starting point for DNA polymerase to begin synthesis.</p> Signup and view all the answers

    What happens during the elongation step of DNA replication?

    <p>Complementary base pairs are added to the growing DNA strand.</p> Signup and view all the answers

    What is the first step in the transcription process?

    <p>Initiation</p> Signup and view all the answers

    During transcription, which nucleotide pairs with adenine in the DNA strand?

    <p>Uracil</p> Signup and view all the answers

    Which role does mRNA play in protein synthesis?

    <p>It encodes the amino acid sequence of a protein.</p> Signup and view all the answers

    Which of the following correctly describes the elongation phase of transcription?

    <p>Nucleotides are added to the growing mRNA strand.</p> Signup and view all the answers

    What occurs during the termination phase of transcription?

    <p>The mRNA strand is completed and detaches from DNA.</p> Signup and view all the answers

    In the translation process, which complex serves as the site for protein synthesis?

    <p>Ribosome</p> Signup and view all the answers

    What is the active site of the ribosome primarily composed of?

    <p>rRNA</p> Signup and view all the answers

    Which of the following best describes the role of tRNA during translation?

    <p>It transports amino acids to the ribosome for assembly.</p> Signup and view all the answers

    What role does mRNA play in the process of protein synthesis?

    <p>mRNA serves as a template for the assembly of proteins.</p> Signup and view all the answers

    Which process involves the conversion of DNA into RNA?

    <p>Transcription</p> Signup and view all the answers

    What happens during the translation process?

    <p>The ribosomes read mRNA to assemble amino acids into proteins.</p> Signup and view all the answers

    In terms of mutations, which of the following statements is true?

    <p>Some mutations can be beneficial and contribute to evolution.</p> Signup and view all the answers

    Which of the following is NOT a mechanism by which mutations can occur?

    <p>Hydrolysis of proteins</p> Signup and view all the answers

    What is a possible effect of a silent mutation?

    <p>No change in the protein's function.</p> Signup and view all the answers

    What differentiates transcription from replication?

    <p>Transcription uses RNA polymerase instead of DNA polymerase.</p> Signup and view all the answers

    Which type of mutation is likely to alter the reading frame of a gene?

    <p>Frameshift mutation</p> Signup and view all the answers

    Which term describes the outcome when proofreading and repair mechanisms fail during DNA replication?

    <p>Mutation</p> Signup and view all the answers

    How does the ribosome facilitate translation?

    <p>By joining amino acids to form polypeptides.</p> Signup and view all the answers

    How does DNA ligase contribute to lagging strand replication?

    <p>It joins Okazaki fragments into a continuous strand.</p> Signup and view all the answers

    What is the primary role of messenger RNA (mRNA) in protein synthesis?

    <p>To carry genetic information from DNA to ribosomes.</p> Signup and view all the answers

    Which statement describes transcription accurately?

    <p>mRNA is synthesized from the DNA template.</p> Signup and view all the answers

    What role do telomeres play in DNA structure?

    <p>They provide protective caps at the end of chromosomes.</p> Signup and view all the answers

    What type of mutation introduces a stop codon prematurely?

    <p>Nonsense mutation</p> Signup and view all the answers

    What is the significance of Okazaki fragments during DNA replication?

    <p>They are synthesized in a discontinuous manner and later joined.</p> Signup and view all the answers

    What action is performed by exonucleases during DNA replication?

    <p>They remove RNA primers and replace them with DNA bases.</p> Signup and view all the answers

    In which way can a mutation affect protein synthesis?

    <p>By altering the genetic message and affecting amino acid sequence.</p> Signup and view all the answers

    What is the main function of telomerase in relation to DNA?

    <p>It synthesizes telomere sequences at the ends of DNA strands.</p> Signup and view all the answers

    What distinguishes the mechanism of lagging strand replication from leading strand replication?

    <p>Lagging strand replication requires more primers.</p> Signup and view all the answers

    What is the primary function of mRNA in protein synthesis?

    <p>To carry information from DNA to ribosomes</p> Signup and view all the answers

    Which sequence of events correctly outlines the steps of translation?

    <p>Initiation, Elongation, Termination</p> Signup and view all the answers

    What is a codon?

    <p>A sequence of three mRNA nucleotides that codes for an amino acid</p> Signup and view all the answers

    What defines a mutation in genetic terms?

    <p>A change in the DNA sequence of an organism</p> Signup and view all the answers

    Which type of mutation can be passed to future generations?

    <p>Germ cell mutation</p> Signup and view all the answers

    During which phase does the polypeptide chain continue to grow till a stop codon is reached?

    <p>Elongation</p> Signup and view all the answers

    What role does peptidyl transferase play in translation?

    <p>It facilitates the elongation of the polypeptide chain</p> Signup and view all the answers

    What is the effect of a mutation that occurs in somatic cells?

    <p>It affects all future somatic cells derived from it</p> Signup and view all the answers

    What causes mutations to occur?

    <p>Exposure to mutagens and errors in DNA replication</p> Signup and view all the answers

    Which codon signals the start of protein synthesis?

    <p>AUG</p> Signup and view all the answers

    Which genetic disorder is caused by a mutation in the HEXA gene?

    <p>Tay-Sachs Disease</p> Signup and view all the answers

    What genetic disorder is characterized by the presence of an extra copy of chromosome 21?

    <p>Down Syndrome</p> Signup and view all the answers

    What genetic disorder is characterized by a deletion of a specific region of chromosome 15 and causes a happy demeanor?

    <p>Angelman Syndrome</p> Signup and view all the answers

    Which explanation describes how viruses reproduce?

    <p>They invade host cells and disrupt their normal function.</p> Signup and view all the answers

    Which genetic engineering process focuses on constructing DNA from two different sources?

    <p>Recombinant DNA technology</p> Signup and view all the answers

    What is the primary function of ribonucleic acid (RNA) in cells?

    <p>Synthesis of proteins</p> Signup and view all the answers

    Which statement best describes the nature of nucleic acids?

    <p>They consist of monomer units called nucleotides.</p> Signup and view all the answers

    How is genetic information primarily passed from one generation to the next?

    <p>By means of nucleic acids</p> Signup and view all the answers

    Which type of nucleic acid is specifically involved in the process of transcription?

    <p>Ribonucleic acid (RNA)</p> Signup and view all the answers

    Which function of nucleic acids pertains to directing the synthesis of proteins?

    <p>Growth and development</p> Signup and view all the answers

    What is the basic structural unit that makes up nucleic acids?

    <p>Nucleotide</p> Signup and view all the answers

    What characterizes the DNA double helix structure?

    <p>Complementary strands that run anti-parallel to each other</p> Signup and view all the answers

    What is one of the evolutionary roles of nucleic acids?

    <p>Facilitating genetic variation</p> Signup and view all the answers

    What initiates the process of translation in protein synthesis?

    <p>The attachment of mRNA to the ribosome</p> Signup and view all the answers

    Which codon is recognized as the start codon in the genetic code?

    <p>AUG</p> Signup and view all the answers

    What is a mutation in an organism?

    <p>A change in the DNA sequence</p> Signup and view all the answers

    What is the total number of different mRNA codons present in the genetic code?

    <p>64</p> Signup and view all the answers

    How are mutations in somatic cells characterized in terms of inheritance?

    <p>They are passed to all other somatic cells derived from it.</p> Signup and view all the answers

    Which statement is true about the order of codons in mRNA?

    <p>It dictates the order of amino acids in a polypeptide chain.</p> Signup and view all the answers

    What role does peptidyl transferase play during translation?

    <p>It catalyzes the formation of peptide bonds between amino acids.</p> Signup and view all the answers

    Which codons are recognized as stop codons in the genetic code?

    <p>UAA, UAG, UGA</p> Signup and view all the answers

    What is the end product of the elongation phase in translation?

    <p>A completed polypeptide chain</p> Signup and view all the answers

    What characterizes the tertiary structure of nucleic acids?

    <p>Complex folding of large nucleic acids</p> Signup and view all the answers

    Which aspect accurately describes hydrogen bonding in DNA base pairs?

    <p>Adenine and Thymine pair with 2 hydrogen bonds</p> Signup and view all the answers

    What is the significance of the sugar-phosphate backbone in DNA?

    <p>It provides structural stability to the double helix.</p> Signup and view all the answers

    What percentage of human DNA is composed of guanine?

    <p>20%</p> Signup and view all the answers

    What orientation do the polynucleotide strands have in DNA?

    <p>Anti-parallel, one running 5’ to 3’ and the other 3’ to 5’</p> Signup and view all the answers

    Which characteristic of the DNA double helix contributes to its stability?

    <p>Hydrogen bonds between base pairs</p> Signup and view all the answers

    Which of the following describes the arrangement of bases in the DNA molecule?

    <p>Bases are bonded to the sugar-phosphate backbone</p> Signup and view all the answers

    Which feature of the DNA double helix facilitates its helical structure?

    <p>Base pair stacking interactions</p> Signup and view all the answers

    Which of the following best explains why A-T pairs are easier to separate than C-G pairs?

    <p>A-T pairs form 2 hydrogen bonds</p> Signup and view all the answers

    What characteristic of DNA structure is associated with specific pairing between adenine and thymine?

    <p>Two hydrogen bonds connecting them</p> Signup and view all the answers

    What characterizes point mutations?

    <p>They occur through the replacement of one nucleotide with another.</p> Signup and view all the answers

    Which type of mutation introduces a stop codon prematurely?

    <p>Nonsense mutation</p> Signup and view all the answers

    What is one consequence of a deletion mutation?

    <p>It can disrupt gene function due to loss of genetic material.</p> Signup and view all the answers

    What impact do spontaneous mutations have on DNA?

    <p>They result from uncorrected errors during DNA replication.</p> Signup and view all the answers

    In what way can transposable elements affect genetic material?

    <p>They integrate into new locations within chromosomes.</p> Signup and view all the answers

    What is the primary characteristic of a missense mutation?

    <p>It results in a different amino acid being incorporated into a protein.</p> Signup and view all the answers

    Which type of single-gene disorder is caused by mutations in the HBB gene?

    <p>Sickle cell anemia</p> Signup and view all the answers

    What is an outcome of insertion mutations?

    <p>They can disrupt the reading frame, affecting protein synthesis.</p> Signup and view all the answers

    What is the primary role of the CFTR gene?

    <p>To encode proteins responsible for chloride ion transport.</p> Signup and view all the answers

    How can harmful environmental agents contribute to mutations?

    <p>They can induce changes in DNA structure resulting in mutations.</p> Signup and view all the answers

    What percentage of human DNA is made up of cytosine?

    <p>20%</p> Signup and view all the answers

    Which pairing of bases in DNA is easier to separate due to the number of hydrogen bonds?

    <p>Adenine – Thymine</p> Signup and view all the answers

    What structural characteristic uniquely describes the orientation of the two strands in DNA?

    <p>Antiparallel orientation</p> Signup and view all the answers

    How many base pairs are present per helical turn in the DNA structure?

    <p>10.5</p> Signup and view all the answers

    What is the main component of the backbone of DNA?

    <p>Sugar-Phosphate</p> Signup and view all the answers

    What is the diameter of a DNA double helix?

    <p>20 Å</p> Signup and view all the answers

    In which structure does the complex folding of large nucleic acids, such as chromosomes, occur?

    <p>Tertiary structure</p> Signup and view all the answers

    What type of attack is the phosphorus atom in nucleic acids a target for?

    <p>Nucleophilic attack</p> Signup and view all the answers

    What is the effect of higher GC content on DNA stability?

    <p>It increases DNA stability.</p> Signup and view all the answers

    What is the primary process used to create identical copies of DNA?

    <p>Replication</p> Signup and view all the answers

    Where does DNA replication occur in a cell?

    <p>In the nucleus</p> Signup and view all the answers

    What occurs during DNA denaturation?

    <p>Separation of DNA strands</p> Signup and view all the answers

    Which form of DNA is characterized as a right-handed double helix?

    <p>B form</p> Signup and view all the answers

    According to Chargaff's rule, which statement is true?

    <p>A content equals T content.</p> Signup and view all the answers

    What type of interactions primarily stabilize base pairs in DNA?

    <p>Hydrogen bonding</p> Signup and view all the answers

    What defines the primary features of the A form of DNA?

    <p>Wider turn, favored in low water environments</p> Signup and view all the answers

    What is the correct sequence of bases complementary to 5′ A–A–T–G–C–A–G–C–T 3′?

    <p>3′ T–T–A–C–G–T–C–G–A 5′</p> Signup and view all the answers

    What is the role of the major and minor grooves in DNA?

    <p>Facilitate protein binding and interaction</p> Signup and view all the answers

    What is a key function of DNA replication?

    <p>Faithful transmission of genetic information</p> Signup and view all the answers

    Which enzyme is responsible for unwinding the DNA double helix during replication?

    <p>DNA helicase</p> Signup and view all the answers

    What is the role of the RNA primer during DNA replication?

    <p>To serve as a starting point for DNA synthesis</p> Signup and view all the answers

    In which direction does DNA polymerase synthesize the leading strand during replication?

    <p>5' to 3'</p> Signup and view all the answers

    What is the replication fork?

    <p>The area where DNA is copied</p> Signup and view all the answers

    Which cellular process requires accurate DNA replication to avoid disorders?

    <p>Cell division</p> Signup and view all the answers

    What role does topoisomerase play during DNA replication?

    <p>It unwinds DNA and relieves torsional stress</p> Signup and view all the answers

    Why is DNA replication essential for tissue repair?

    <p>To provide genetic material for new cells</p> Signup and view all the answers

    What happens during the S-phase of the cell cycle?

    <p>DNA replication takes place</p> Signup and view all the answers

    What must occur before DNA can be replicated?

    <p>The double helix must unravel</p> Signup and view all the answers

    What is the role of mRNA in protein synthesis?

    <p>It carries the genetic information from DNA to the ribosomes.</p> Signup and view all the answers

    Which codon is recognized as the start codon in the genetic code?

    <p>AUG</p> Signup and view all the answers

    In which type of cells are mutations passed on to future generations?

    <p>Germ cells</p> Signup and view all the answers

    What occurs during the termination stage of translation?

    <p>The translation machinery stops at a stop codon.</p> Signup and view all the answers

    What best describes a mutation?

    <p>A change in the DNA sequence of an organism.</p> Signup and view all the answers

    What role does RNA polymerase play in transcription?

    <p>It binds to the promoter and synthesizes RNA.</p> Signup and view all the answers

    Which nitrogenous base pairs with adenine during RNA transcription?

    <p>Uracil</p> Signup and view all the answers

    What occurs during the termination stage of transcription?

    <p>The mRNA detaches from the DNA template.</p> Signup and view all the answers

    What is the primary function of ribosomes during translation?

    <p>To decode mRNA and synthesize proteins.</p> Signup and view all the answers

    Which component is predominantly found in ribosomes?

    <p>rRNA</p> Signup and view all the answers

    What is the relationship between mRNA and amino acids during translation?

    <p>mRNA directs the sequence of amino acids.</p> Signup and view all the answers

    What significant change occurs in RNA compared to DNA?

    <p>RNA uses ribose instead of deoxyribose.</p> Signup and view all the answers

    During elongation in transcription, what process is occurring?

    <p>RNA nucleotides are added to mRNA.</p> Signup and view all the answers

    What is the main purpose of translation?

    <p>To synthesize proteins based on mRNA codons.</p> Signup and view all the answers

    Which stage of protein synthesis occurs first?

    <p>Initiation</p> Signup and view all the answers

    What process occurs after a virus injects its nucleic acid into a host cell?

    <p>The viral nucleic acid is replicated.</p> Signup and view all the answers

    What component is typically found in a vaccine?

    <p>An inactive or weakened form of a virus.</p> Signup and view all the answers

    How do antibodies function against viruses or bacteria in the context of a vaccine?

    <p>They are produced against inactive viral or bacterial envelopes.</p> Signup and view all the answers

    What is the first step a virus takes to infect a host cell?

    <p>It attaches to the host cell's external surface.</p> Signup and view all the answers

    Which of the following is a characteristic of viral infection in host cells?

    <p>A hole forms in the host cell membrane allowing entry.</p> Signup and view all the answers

    What effect does increased GC content have on a DNA molecule?

    <p>It increases the stability of DNA.</p> Signup and view all the answers

    What is the major groove in the context of DNA structure?

    <p>Where the backbones are far apart.</p> Signup and view all the answers

    Which form of DNA is characterized as a right-handed double helix with a wider turn?

    <p>A form</p> Signup and view all the answers

    What occurs during DNA denaturation?

    <p>The hydrogen bonds between strands are destroyed.</p> Signup and view all the answers

    What is the primary characteristic of the double helix structure of DNA?

    <p>It is composed of two anti-parallel polynucleotides.</p> Signup and view all the answers

    Which nucleotide pairing is easier to separate due to the number of hydrogen bonds?

    <p>Adenine and Thymine</p> Signup and view all the answers

    What principle does Chargaff's rule illustrate?

    <p>A equals T and G equals C in DNA composition.</p> Signup and view all the answers

    During which phase does DNA replication occur in the cell cycle?

    <p>Interphase</p> Signup and view all the answers

    What percentage of Cytosine is found in human DNA if it contains 30% Adenine?

    <p>20%</p> Signup and view all the answers

    What type of bond primarily forms between complementary base pairs?

    <p>Hydrogen bonds</p> Signup and view all the answers

    How many bases are there in each complete helical turn of DNA?

    <p>10.5 bases</p> Signup and view all the answers

    What happens to the DNA helix during the transcription phase of the central dogma?

    <p>The DNA helix unwinds and separates.</p> Signup and view all the answers

    Which statement correctly describes the stability of DNA?

    <p>Hydrogen bonding between bases contributes significantly to stability.</p> Signup and view all the answers

    What is the significance of the 5' to 3' directionality in the strands of DNA?

    <p>It ensures that the strands can undergo replication.</p> Signup and view all the answers

    Which bases are paired according to complementary base pairing in DNA?

    <p>A pairs with T</p> Signup and view all the answers

    What role does the proofreading mechanism play in DNA replication?

    <p>It corrects most replication errors.</p> Signup and view all the answers

    Which of the following statements about DNA's three-dimensional structure is true?

    <p>The backbone of DNA is composed of sugar-phosphate groups.</p> Signup and view all the answers

    Which feature characterizes the tertiary structure of nucleic acids?

    <p>Complex folding of large nucleic acids.</p> Signup and view all the answers

    What is Tay-Sachs Disease caused by?

    <p>A mutation in the HEXA gene</p> Signup and view all the answers

    Which genetic disorder is characterized by the presence of an extra X chromosome in males?

    <p>Klinefelter Syndrome</p> Signup and view all the answers

    What is recombinant DNA best defined as?

    <p>DNA containing genetic material from two different organisms</p> Signup and view all the answers

    What characterizes Angelman Syndrome?

    <p>Deletion of a specific region on chromosome 15</p> Signup and view all the answers

    Which of the following statements about Down Syndrome is correct?

    <p>It is a result of an extra copy of chromosome 21.</p> Signup and view all the answers

    Which genetic disorder affects females and is characterized by the absence of one X chromosome?

    <p>Turner Syndrome</p> Signup and view all the answers

    What is the primary function of viruses in host cells?

    <p>To reproduce by invading host cells</p> Signup and view all the answers

    What is a primary characteristic of Prader-Willi Syndrome?

    <p>Intellectual disability and obesity</p> Signup and view all the answers

    How are host cells affected by viral infections?

    <p>Their normal function is disrupted.</p> Signup and view all the answers

    Which disorder is characterized by a genetic deletion affecting chromosome 15 and results in a 'happy demeanor'?

    <p>Angelman Syndrome</p> Signup and view all the answers

    What are transposable elements?

    <p>Segments of DNA that can insert themselves anywhere in chromosomes</p> Signup and view all the answers

    What characterizes point mutations?

    <p>They involve the replacement of one base with another</p> Signup and view all the answers

    What is a missense mutation?

    <p>It leads to a different amino acid being incorporated</p> Signup and view all the answers

    Which type of mutation can lead to a truncated protein?

    <p>Nonsense mutation</p> Signup and view all the answers

    What genetic disorder is caused by mutations in the CFTR gene?

    <p>Cystic Fibrosis</p> Signup and view all the answers

    What is a common consequence of frame-shift mutations?

    <p>They can disrupt the reading frame of the gene</p> Signup and view all the answers

    Which two genes are associated with hemophilia?

    <p>F8 and F9</p> Signup and view all the answers

    What distinguishes a silent mutation from other mutations?

    <p>It does not affect the amino acid sequence</p> Signup and view all the answers

    What type of mutation involves the removal of a segment of DNA?

    <p>Deletion</p> Signup and view all the answers

    Which of the following disorders is due to a mutation in the HTT gene?

    <p>Huntington's Disease</p> Signup and view all the answers

    Study Notes

    Nucleotides and Nucleic Acids

    • Nucleotides have a varied role in metabolism, including energy currency, chemical links in cellular responses, structural components of cofactors, and most importantly as constituents of nucleic acids.

    • DNA primarily serves as a storehouse of biological information and transmits this information across generations.

    • A gene is a DNA segment containing information for a functional biological product, such as a protein or RNA.

    • RNA is categorized into:

      • Ribosomal RNA (rRNA): Component of the ribosome, responsible for protein synthesis.
      • Messenger RNA (mRNA): Intermediate between DNA and protein, carries the code for protein synthesis.
      • Transfer RNA (tRNA): Adapter molecules that bind to amino acids and recognize codons on mRNA, facilitating protein synthesis.
      • Non-coding RNA: Diverse functions, including splicing mRNA and silencing specific parts of the genome.

    • Nucleotides consist of three components: a nitrogenous base, a pentose sugar (ribose or deoxyribose), and at least one phosphate group.

    • Nitrogenous bases are either pyrimidines (single-ring structures) or purines (double-ring structures):

      • Pyrimidines in DNA: Cytosine (C) and Thymine (T)
      • Pyrimidines in RNA: Cytosine (C) and Uracil (U)
      • Purines in DNA and RNA: Adenine (A) and Guanine (G)

    • Nucleosides are nitrogenous bases linked to a pentose sugar, lacking a phosphate group.

    • The presence or absence of a hydroxyl group at the 2' position of the pentose sugar distinguishes DNA (deoxyribose, no hydroxyl) from RNA (ribose, hydroxyl).

    • Deoxyribonucleotides are the building blocks of DNA, while ribonucleotides form RNA.

    • The phosphodiester bond connects nucleotides in DNA and RNA, linking the 5' phosphate of one nucleotide to the 3' hydroxyl of the next.

    • RNA is more susceptible to hydrolysis under alkaline conditions due to the presence of a hydroxyl group at the 2' position, facilitating nucleophilic attack on the phosphate group.

    • Nucleic acids exhibit hierarchical levels of structure:

      • Primary structure: Nucleotide sequence and covalent bonds.
      • Secondary structure: Regular stable structure, common to all nucleic acids.
      • Tertiary structure: Complex folding of large nucleic acids, such as chromosomes, tRNA, and rRNA.

    • The Watson-Crick model describes the structure of DNA as a double helix, consisting of two antiparallel strands.

    • The double helix structure creates major and minor grooves that are important for protein and enzyme binding.

    • Base pairing, which occurs between complementary strands, involves specific hydrogen bonding patterns:

      • Adenine (A) pairs with Thymine (T) in DNA and Uracil (U) in RNA.
      • Guanine (G) pairs with Cytosine (C).

    • Despite their importance, hydrogen bonds contribute minimally to the stability of DNA. The major contributor is the presence of metal ions, such as magnesium (Mg2+), that neutralize the negative charges of the phosphate backbone.

    • The phosphate backbone, located on the outside of the double helix, is highly hydrophilic and interacts with water molecules.

    DNA Structure

    • Backbone - Negatively charged phosphate groups provide stability
    • Base Stacking Interactions - Van der Waals forces between stacked base pairs also contributes to stability
    • GC content - Higher GC content leads to a more stable DNA molecule
    • DNA Forms - Three forms exist: A, B, and Z
      • B form - Most stable, right-handed double helix, Watson-Crick structure, predominant form in physiological conditions
      • A form - Right-handed double helix, wider turn, favored in solutions lacking water
      • Z form - Left-handed helix, zigzag appearance, elongated and slender
    • Palindrome Sequences - Occur in DNA as a mirror repeat with inverted and repeated sequences
    • Cruciforms - Double helix with two hairpin structures formed by complementary regions in the sequence

    RNA Structure

    • mRNA - Messenger RNA, carries genetic information from DNA to ribosomes
      • Monocistronic mRNA - Codes for one polypeptide
      • Polycistronic mRNA - Codes for two or more polypeptides
      • Single-stranded - Necessary for interaction with ribosomes and tRNAs
    • Secondary Structure - More complex than DNA, with various folds and loops
    • tRNA - Transfer RNA, contains domains involved in amino acid binding and translation
    • Hairpins - Most common secondary structure in RNA
    • Base Stacking - Stronger between purine bases, contributes to stability

    Nucleotides and Nucleic Acids

    • Nucleotides play essential roles in metabolism, including energy storage, signal transduction, and as building blocks for nucleic acids.
    • DNA serves as the primary repository of genetic information, passed down through generations.
    • Genes are segments of DNA encoding functional products like proteins or RNA molecules.
    • RNA is categorized into distinct types based on its function:
      • Ribosomal RNA (rRNA): Component of the ribosome, responsible for protein synthesis.
      • Messenger RNA (mRNA): Carries genetic instructions from DNA to the ribosomes for protein synthesis.
      • Transfer RNA (tRNA): Adaptor molecules that bring amino acids to the ribosome, guided by mRNA codons during protein synthesis.
      • Non-coding RNA: Diverse functions, including splicing mRNA and regulating gene expression.
    • Nucleotides are composed of three main components:
      • Nitrogenous base: A purine (adenine, guanine) or pyrimidine (cytosine, thymine, uracil).
      • Pentose sugar: Either ribose (in RNA) or deoxyribose (in DNA) depending on the presence or absence of a hydroxyl group at the 2' position.
      • Phosphate group: One or more phosphate groups attached to the sugar.
    • Nucleosides, lacking the phosphate group, consist of a nitrogenous base linked to a pentose sugar.
    • Deoxyribonucleotides are the building blocks of DNA, while ribonucleotides form RNA.
    • The phosphodiester bond links nucleotides in DNA and RNA, connecting a 5' phosphate of one nucleotide to the 3' hydroxyl of the next.
    • RNA is more susceptible to alkaline hydrolysis due to the 2' hydroxyl group, which facilitates nucleophilic attack on the phosphate group.
    • Nucleic acids exhibit hierarchical levels of structure:
      • Primary structure: Nucleotide sequence and covalent bonds.
      • Secondary structure: Stable, regular structures common to all nucleic acids.
      • Tertiary structure: Complex folding of large nucleic acids, such as chromosomes, tRNA, and rRNA.
    • The Watson-Crick model describes DNA as a double helix composed of two antiparallel strands.
    • Major and minor grooves form in the double helix, essential for protein and enzyme binding.
    • Base pairing, involving specific hydrogen bonding patterns, occurs between complementary strands:
      • Adenine (A) pairs with Thymine (T) in DNA and Uracil (U) in RNA
      • Guanine (G) pairs with Cytosine (C).
    • Hydrogen bonds contribute minimally to DNA stability; metal ions like magnesium (Mg2+) play a crucial role in neutralizing the negatively charged phosphate backbone.
    • The phosphate backbone, located on the outside of the double helix, is hydrophilic and interacts with water molecules.

    DNA Structure

    • Backbone - Negatively charged phosphate groups contribute to the stability of DNA.
    • Base Stacking Interactions - Van der Waals forces between stacked base pairs also contribute to stability.
    • GC content - DNA with higher GC content is more stable due to the three hydrogen bonds between guanine and cytosine.
    • DNA Forms - Three forms of DNA exist, A, B, and Z:
      • B form - Most stable, right-handed double helix, Watson-Crick structure, predominant form in physiological conditions.
      • A form - Right-handed double helix, wider turn, favored in solutions lacking water.
      • Z form - Left-handed helix, zigzag appearance, elongated and slender.
    • Palindrome Sequences - Sequences in DNA where a segment is repeated in an inverted and complementary way.
    • Cruciforms - Double helix with two hairpin structures formed by complementary regions in the sequence.

    RNA Structure

    • mRNA - Messenger RNA carries genetic information from DNA to ribosomes for protein synthesis.
      • Monocistronic mRNA - Codes for one polypeptide.
      • Polycistronic mRNA - Codes for multiple polypeptides.
      • Single-stranded - Necessary for interaction with ribosomes and tRNAs during protein synthesis.
    • Secondary Structure - RNA's structure is more complex than DNA, featuring folds and loops.
    • tRNA - Transfer RNA; contains specific domains for amino acid binding and translation.
    • Hairpins - The most common secondary structure in RNA.
    • Base Stacking - Stronger between purine bases, contributing to RNA stability.

    Nucleotides

    • Nucleotides are essential building blocks for nucleic acids (DNA and RNA), and play vital roles in cellular metabolism.
    • They are composed of three components:
      • A nitrogenous base: Adenine, Guanine, Cytosine, Thymine (DNA only), or Uracil (RNA only)
      • A pentose sugar: Deoxyribose (DNA) or Ribose (RNA)
      • At least one phosphate group
    • A nucleoside is a nitrogenous base attached to a pentose sugar, lacking the phosphate group.

    Nucleic Acids

    • DNA primarily acts as a repository of genetic information, responsible for storing and transmitting it across generations.
    • RNA molecules have distinct classes with diverse roles:
      • Ribosomal RNA (rRNA): Essential component of ribosomes, responsible for protein synthesis.
      • Messenger RNA (mRNA): Transmits genetic information from DNA to ribosomes, directing protein synthesis.
      • Transfer RNA (tRNA): Adaptor molecules that deliver amino acids to ribosomes during translation.
      • Non-coding RNA: Plays a variety of regulatory roles, including splicing RNA, silencing genes, and controlling gene expression.

    DNA Structure

    • DNA consists of two antiparallel strands, forming a double helix structure.
    • Each strand has a 5’ end (phosphate group) and a 3’ end (hydroxyl group).
    • The two strands are held together by hydrogen bonds between complementary base pairs:
      • Adenine (A) pairs with Thymine (T)
      • Guanine (G) pairs with Cytosine (C)
    • The double helix features major and minor grooves, serving as binding sites for proteins and enzymes.
    • The phosphate backbone carries a negative charge, shielded by metal ions like magnesium (Mg2+), ensuring DNA stability.
    • Base stacking interactions also contribute to DNA stability.
    • DNA can exist in three forms:
      • B-form (most common in physiological conditions)
      • A-form (favored in dehydrated conditions)
      • Z-form (left-handed helix with a zigzag appearance)
    • Palindromic sequences read the same forward and backward, allowing for specific DNA cleavage by restriction enzymes.

    RNA Structure

    • RNA is a single-stranded molecule that folds into a right-handed helix.
    • Base stacking interactions stabilize its structure, with purine-rich regions exhibiting particular stability.
    • RNA can base pair with DNA (transcription) or other RNA molecules (RNA-RNA interactions).
    • RNA's secondary structure is complex and can include:
      • Hairpins
      • Cruciforms
      • Bulges
      • Loops
    • tRNA has specific domains with a binding site for amino acids.

    DNA Replication

    • DNA replication involves the separation of the two parent strands, allowing each to serve as a template for the synthesis of a new complementary daughter strand.
    • Each new DNA molecule consists of one parent strand and one newly synthesized daughter strand, ensuring the faithful transmission of genetic information.

    Important Considerations

    • Messenger RNA (mRNA) can be:
      • Monocistronic: One mRNA codes for a single polypeptide.
      • Polycistronic: One mRNA codes for two or more polypeptides.
    • Transcription is the process of copying genetic information from DNA to mRNA.

    Nucleotides

    • Nucleotides are the building blocks of nucleic acids.
    • They are composed of a nitrogenous base, a pentose sugar, and at least one phosphate group.
    • The phosphate group is negatively charged and gives nucleotides their acidic properties.
    • The pentose sugar can be ribose (in RNA) or deoxyribose (in DNA).
    • The primary difference between ribose and deoxyribose is the presence of a hydroxyl group at the 2' position in ribose.
    • The nitrogenous bases are either purines (adenine and guanine) or pyrimidines (cytosine, thymine, and uracil).
    • Thymine is only found in DNA, while uracil replaces it in RNA.

    Nucleic Acids

    • Nucleic acids are polymers made up of long chains of nucleotides linked together by phosphodiester bonds.
    • These bonds form between the 5' phosphate of one nucleotide and the 3' hydroxyl of the next nucleotide.
    • DNA is more resistant to hydrolysis than RNA due to the absence of the 2' hydroxyl group in deoxyribose.
    • Nucleic acids exhibit hierarchical levels of structure including primary, secondary, and tertiary structure.

    DNA Structure

    • The primary structure of DNA refers to the sequence of nucleotides and covalent bonds.
    • The secondary structure of DNA is the well-known double helix, which is stabilized by hydrogen bonding between base pairs and hydrophobic interactions between the bases.
    • Guanine pairs with cytosine (G-C) via three hydrogen bonds, while adenine pairs with thymine (A-T) via two hydrogen bonds.
    • The two strands of DNA are antiparallel, meaning they run in opposite directions.
    • DNA can exist in three forms: A, B, and Z.
    • The B form is the most common and stable under physiological conditions.
    • The A form is favored in solutions lacking water.
    • The Z form is a left-handed helix with a zigzaggy appearance.

    RNA Structure and Function

    • RNA is a single-stranded nucleic acid that plays multiple roles in the cell.
    • The primary structure of RNA refers to the sequence of nucleotides and covalent bonds.
    • The secondary structure of RNA is more complex than DNA, with various structures such as bulges, loops, and internal loops.
    • The tertiary structure refers to the three-dimensional folding of larger RNA molecules.
    • Three major types of RNA:
      • Messenger RNA (mRNA) carries genetic information from DNA to the ribosome for protein synthesis.
      • Ribosomal RNA (rRNA) is a component of the ribosome, which is essential for protein synthesis.
      • Transfer RNA (tRNA) carries amino acids to the ribosome for protein synthesis, acting as an adaptor molecule.

    tRNA Structure and Function

    • tRNA is a crucial molecule in translation as it carries specific amino acids to the ribosome.
    • tRNA has a specific domain for amino acid binding.
    • tRNA contains a variety of domains, such as the C domain and the S domain.
    • Hairpins are the most common secondary structure in RNA, exemplified by tRNA.
    • The folding of tRNA forms a complex and intricately shaped structure.

    Nucleotides and Their Roles

    • Nucleotides are the building blocks of nucleic acids (DNA and RNA).
    • DNA stores and transmits biological information across generations.
    • A gene is a DNA segment containing information to synthesize a functional product, such as a protein or RNA.

    RNA: Beyond DNA

    • Ribosomal RNA (rRNA) is a component of the ribosome, responsible for protein synthesis.
    • Messenger RNA (mRNA) carries genetic information from DNA to the ribosome for protein translation.
    • Transfer RNA (tRNA) acts as an adapter molecule, linking specific amino acids to codons on mRNA during protein synthesis.
    • Non-coding RNA (ncRNA) has various functions, including splicing mRNA and regulating gene expression.

    Nucleotide Structure

    • Nucleotides consist of a nitrogenous base, a pentose sugar, and at least one phosphate group.
    • Nitrogenous bases are either pyrimidines (cytosine, uracil, and thymine) or purines (adenine and guanine).
    • A nucleoside is a nitrogenous base linked to a pentose sugar without a phosphate group.
    • DNA and RNA are distinguished by the presence of deoxyribose (DNA) or ribose (RNA) at the 2' position of their pentose sugar.

    Major Purines and Pyrimidines

    • Adenine, guanine, cytosine, and thymine are found in DNA.
    • Adenine, guanine, cytosine, and uracil are found in RNA.

    Phosphodiester Bonds

    • Phosphodiester bonds connect nucleotides to form nucleic acid chains.
    • The 5' phosphate of one nucleotide forms a covalent bond with the 3' hydroxyl group of the next nucleotide.
    • RNA is more susceptible to hydrolysis than DNA due to the presence of the 2' hydroxyl group.
    • The hydroxyl group can act as a nucleophile to attack the phosphodiester bond.

    Nucleic Acid Structure

    • Nucleic acids exhibit hierarchical levels of structure, including primary, secondary, and tertiary structures.
    • The primary structure refers to the nucleotide sequence and covalent bonds within the molecule.
    • Secondary structure is the stable structure formed by the nucleic acid, such as double helical DNA.
    • Tertiary structure refers to the complex folding of larger molecules, such as chromosomes.

    DNA Structure

    • DNA is a double helix composed of two anti-parallel polynucleotide strands.
    • The strands are held together by hydrogen bonds between complementary base pairs (A-T and G-C).
    • The double helix has a major groove and a minor groove, serving as binding sites for proteins and enzymes.
    • The hydrogen bonds contribute less to DNA stability than the stacking interactions of the bases and the interactions between the negatively charged phosphate backbone and metal ions (e.g., Mg2+).

    DNA Structure

    • DNA has a phosphate backbone that repels negatively charged ions and shields the negative charge of the nucleotides.
    • Base stacking interactions between nucleotides stabilize DNA structure.
    • Base stacking interactions are van der Waals interactions between stacked base pairs.
    • Guanine-Cytosine (GC) base pairs are more stable than Adenine-Thymine (AT) pairs.
    • DNA can exist in different 3D forms (A, B, and Z forms).
    • B-form DNA is the most stable form and is present under physiological conditions.
    • A-form DNA is a right-handed double helix present in solutions without water.
    • Z-form DNA is a left-handed double helix with a zigzag shape.
    • Palindromes in DNA sequences can result in altered DNA structure.
    • Mirror repeats are inverted sequences that can also affect DNA structure.
    • Hairpins are formed when complementary regions of DNA base pair, creating a loop structure.
    • Cruciforms are formed when two hairpins come together, creating four arms with a central loop.

    RNA Structure

    • RNA is single-stranded.
    • RNA forms its own right-handed helical structure.
    • Base stacking interactions are strongest in RNA when two purines are stacked together.
    • RNA can base pair with complementary regions of DNA or RNA in an antiparallel fashion.
    • The secondary structure of RNA can be complex with bulges, loops, and internal loops formed by mismatches.
    • tRNA is a specific type of RNA with different domains (C and S) that bind to amino acids.
    • Hairpins are the most common secondary structure in RNA.

    DNA Replication

    • DNA needs to be replicated to make copies of genetic information.
    • Replication involves separating the two parent strands of DNA and using each as a template to create two new daughter strands.
    • Each new DNA molecule has one parent strand and one daughter strand.

    Nucleotides

    • They are building blocks of DNA and RNA.
    • Composed of a nitrogenous base, a pentose sugar, and at least one phosphate group.
    • Nitrogenous bases can be purines (adenine, guanine) or pyrimidines (cytosine, thymine, uracil).
    • Pentose sugar can be ribose (RNA) or deoxyribose (DNA).
    • Nucleosides lack the phosphate group, consisting only of a nitrogenous base and a pentose sugar.
    • Cyclical AMP (cAMP) and cyclic GMP (cGMP) are key signaling molecules.

    Nucleic Acids

    • DNA and RNA are nucleic acids responsible for storing and transmitting genetic information.
    • DNA is a double helix structure, with two antiparallel strands held together by hydrogen bonds between complementary bases.
    • RNA is generally single-stranded and can fold into complex structures.
    • Nucleotides are linked by phosphodiester bonds, forming a sugar-phosphate backbone.
    • RNA is more susceptible to hydrolysis than DNA due to the 2'-hydroxyl group.
    • Nucleic acids absorb UV light at 260 nm, a property used for quantification.
    • They exhibit hierarchical structural organization, including primary (nucleotide sequence), secondary (stable structures), and tertiary (complex folding).

    DNA Structure

    • The Watson-Crick model describes the DNA double helix.
    • Two antiparallel strands wind around each other, forming major and minor grooves.
    • Base pairing is specific: adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C).
    • Hydrogen bonds between bases contribute to stability, along with metal ions like magnesium (Mg2+).
    • DNA exists in three forms: B form (most common), A form (wider, less hydrated), and Z form (left-handed, elongated).

    RNA Structure

    • mRNA carries genetic information from DNA to ribosomes.
    • tRNA acts as an adapter molecule, bringing amino acids for protein synthesis.
    • rRNA is a component of ribosomes.
    • RNA forms a right-handed helix.
    • RNA secondary structure is diverse due to its ability to fold back upon itself.
    • Common RNA structures include hairpins, internal loops, bulges, loops, and stems.

    DNA & RNA

    • DNA is transcribed to RNA
    • Most RNA is single-stranded
    • RNA uses uracil instead of thymine
    • RNA uses ribose instead of deoxyribose

    Transcription

    • Transcription is the process of copying a segment of DNA into RNA.
    • RNA polymerase binds to a region of a gene called the promoter.
    • RNA polymerase reads the unwound DNA strand and builds the mRNA molecule, using complementary base pairs.
    • Termination occurs when RNA polymerase crosses a stop sequence in the gene.

    Translation

    • Translation is the process in which mRNA codons are deciphered and a specific protein molecule is synthesized.
    • Ribosomes are the sites of translation.
    • Ribosomes consist of rRNA and protein.
    • Ribosomes contain four rRNA molecules and 80 proteins in two subunits.
    • rRNA is the active site of the ribosome.

    mRNA

    • mRNA carries protein-building information to ribosomes and tRNA for translation.
    • A codon is a sequence of three mRNA nucleotides that codes for a specific amino acid.
    • The order of codons in mRNA determines the order of amino acids in a polypeptide chain.

    The Genetic Code

    • The genetic code consists of 64 mRNA codons (triplets).
    • Some amino acids can be coded by more than one codon.

    Start and Stop Codons

    • AUG (methionine) is a start codon.
    • UAA, UAG, and UGA are stop codons.

    Protein Synthesis

    • Protein synthesis involves transcription and translation.

    Mutations

    • A mutation is a change in the DNA sequence of an organism.
    • Mutations can result from errors in DNA replication, exposure to mutagens, or viral infection.
    • Mutations in germ cells are passed to future generations.
    • Mutations in somatic cells affect the individual but are not passed to future generations.

    DNA Structure

    • DNA has a negatively charged phosphate backbone, which provides stability.
    • Base stacking interactions contribute to stability.
    • Higher GC content in DNA leads to a more stable structure.
    • DNA exists in three forms: A, B, and Z.

    Base Pairing

    • A pyrimidine always pairs with a purine.
    • Hydrogen bonding is most favored in A–T and G–C pairs.
    • A–T and G–C pairing is termed complementary.

    Chargaff's Rule

    • The content of adenine equals the content of thymine.
    • The content of guanine equals the content of cytosine.
    • In DNA, purine bases always pair with the pyrimidine bases.

    DNA Replication

    • Replication is the doubling process of DNA molecules.
    • The parent molecule unwinds, and two new daughter strands are built based on base pairing rules.

    Where Does Replication Occur?

    • DNA replication occurs in the nucleus during interphase.
    • A cell copies its DNA before mitosis or meiosis.

    Why Is DNA Replication Important?

    • Accurate replication ensures the faithful transmission of genetic information.
    • It is essential for cell growth, tissue repair, and maintenance.
    • It is a prerequisite for cell division.

    Steps in DNA Replication

    • Replication Fork Formation: DNA helicase unwinds the double helix and separates the strands by disrupting the hydrogen bonds. This creates the replication fork.
    • Primer Binding: A short RNA piece, known as a primer, attaches to the 3' end of the leading strand.
    • Elongation: DNA polymerase adds DNA nucleotides to the 3′ end of the newly synthesized strand. This happens continuously on the leading strand.
    • Lagging Strand Replication: The lagging strand is replicated discontinuously. Multiple primers are bound to the lagging strand, and Okazaki fragments are synthesized between the primers.
    • Termination: Exonucleases remove all RNA primers from the DNA strands, and these primers are replaced with DNA bases. DNA ligase joins Okazaki fragments together.
    • Proofreading: DNA polymerase proofreads newly formed DNA to check for, remove, and replace errors.

    Telomeres

    • The ends of linear DNA strands have repeated DNA sequences called telomeres.
    • Telomeres act as protective caps at the ends of chromosomes to prevent fusion with neighboring chromosomes.
    • Telomerase is a special type of DNA polymerase enzyme that synthesizes telomere sequences.

    Types of Nucleic Acids

    • Deoxyribonucleic Acid (DNA): Found within the cell nucleus and acts as the blueprint for protein synthesis, storing and transferring genetic information.
    • Ribonucleic Acid (RNA): Occurs in all parts of a cell, primarily responsible for protein synthesis.
      • Ribosomal RNA (rRNA): Plays a key role in protein synthesis, acting as a catalyst in the process.
      • Messenger RNA (mRNA): Carries genetic information from DNA to ribosomes for protein synthesis.
      • Transfer RNA (tRNA): Delivers amino acids to ribosomes during protein synthesis, pairing with codons on mRNA.

    Nucleic Acid Structure

    • Primary Structure: The linear sequence of nucleotides linked by phosphodiester bonds.
    • Secondary Structure: Regular, stable structures common to all nucleic acids, examples include the double helix in DNA and hairpin loops in RNA.
    • Tertiary structure: Complex folding of nucleic acids, observed in large molecules like chromosomes.

    DNA Structure

    • Double Helix: DNA consists of two polynucleotide strands running anti-parallel to each other, connected by hydrogen bonding between complementary base pairs (A-T & C-G).
      • Adenine (A) forms two hydrogen bonds with Thymine (T).
      • Cytosine (C) forms three hydrogen bonds with Guanine (G).
    • Sugar-Phosphate Backbone: The exterior of the DNA molecule.
    • Hydrophobic Bases: The interior of the DNA molecule.

    Replication of DNA

    • Semiconservative Replication: Each new DNA molecule consists of one original strand and one newly synthesized strand.
    • Steps:
      • Unwinding: The DNA double helix is unwound by enzymes like helicase.
      • Priming: Short RNA sequences act as primers for DNA polymerase.
      • Elongation: DNA polymerase adds new nucleotides to the template strand, following the complementary base pairing rules.
      • Termination: Replication stops when the entire DNA molecule is copied.

    Overview of Protein Synthesis

    • Transcription: The process of copying genetic information from DNA to mRNA.
      • Steps:
        • Initiation: RNA polymerase binds to a promoter region on DNA.
        • Elongation: RNA polymerase moves along the DNA template, synthesizing a complementary mRNA strand.
        • Termination: Transcription stops when RNA polymerase encounters a termination signal on the DNA.
    • Translation: The process of using mRNA to synthesize proteins.
      • Steps:
        • Initiation: The ribosome binds to mRNA, and the first tRNA molecule carrying methionine binds to the start codon (AUG).
        • Elongation: tRNA molecules carry amino acids to the ribosome, where peptide bonds are formed between the amino acids, growing the polypeptide chain.
        • Termination: Translation ends when a stop codon is encountered on mRNA.

    Mutations

    • Point Mutations: Changes occurring at a single nucleotide.
      • Substitution: One base is replaced by another.
        • Missense Mutation: A different amino acid is incorporated into the protein, altering its function.
        • Silent Mutation: No change in protein sequence.
        • Nonsense Mutation: A stop codon is introduced, leading to a truncated protein.
    • Frame-shift Mutations: A base is added or removed, causing a shift in the reading frame of the DNA sequence, potentially disrupting protein function.
      • Insertion: One or more nucleotides are added.
      • Deletion: One or more nucleotides are removed.
    • Duplication: A segment of DNA is duplicated, increasing copies of specific genes.

    Viruses

    • Tiny disease-causing agents with a protein coat.
    • They reproduce by invading host cells and using the host's machinery to produce more viruses.
    • They can infect bacteria, plants, animals, and humans, causing various diseases.

    Polymerase Chain Reaction (PCR)

    • A technique used to amplify specific DNA sequences, creating multiple copies of the desired DNA fragment.
    • It is a fundamental tool in molecular biology, widely used in research and diagnostics.

    Genetic Engineering

    • Altering the DNA of an organism to produce a desired trait.
    • Recombinant DNA: DNA containing genetic material from two different organisms.

    DNA Structure

    • DNA stability is due to its resistance to alkaline conditions
    • DNA lacks a 2’ hydroxyl group that could be targeted by nucleophilic attacks
    • The phosphorus atom is the site of a nucleophilic attack
    • There are different levels of nucleic acid structure
      • Primary: Nucleotide sequence using covalent bonds
      • Secondary: Stable structure common to all nucleic acids
      • Tertiary: Complex folding of large nucleic acids like chromosomes, tRNA and rRNA

    DNA Double Helix

    • The amounts of A, T, G, and C present in DNA molecules helped determine how the molecule is structured in 3D space.
    • The amounts of A & T are always equal and the amounts of C & G are also always equal
    • Human DNA contains:
      • 30% adenine
      • 30% thymine
      • 20% guanine
      • 20% cytosine

    DNA Double Helix (Watson and Crick Model)

    • DNA is composed of two polynucleotides that are anti-parallel to each other.
      • one strand runs from 5’ to 3’ and the other strand runs from 3’ to 5’.
    • The sugar phosphate backbone is located on the outside of the helix
    • Hydrophobic bases are on the inside

    DNA Double Helix (Watson and Crick Model)

    • Two helical DNA strands form a Right-handed double helix
    • The helix has a
      • diameter of 20 Å,
      • 3.4 Å per base,
      • 10.5 bases per helical turn,
      • 36 Å per turn

    DNA Double Helix (Watson and Crick Model)

    • The backbone has negatively charged phosphate groups that provide stability
    • Base stacking interactions that result from van der Waals forces between bases also contribute to stability
    • Higher GC content leads to greater DNA stability

    DNA Forms

    • Three forms exist: A, B and Z
    • B form is the most stable and commonly found in the body
    • A form is found most commonly in solutions lacking water
    • Z form is a left-handed helix

    Base Pairing

    • A pyrimidine is always paired with a purine
      • This allows both to fit within the DNA double strand
      • Hydrogen bonding is favored in A-T and G-C pairs, termed complementary

    Chargaff's Rule

    • The content of Adenine is equal to the content of Thymine
    • The content of Guanine is equal to the content of Cytosine

    Major & Minor Grooves

    • The major groove is found where the backbones are far apart from each other, and the minor groove is located where the backbones are closest together.

    DNA Double Helix (Watson and Crick Model)

    • DNA denaturation can be achieved through breaking the hydrogen bonds of the double stranded helix.
      • This leads to the separation of the two strands, denaturing the DNA from a double stranded to a single stranded molecule

    Central Dogma

    • DNA is transcribed into RNA, which is then translated into protein
    • The central dogma has three processes
      • Replication: makes identical copies of DNA
      • Transcription: reads genetic messages and carries them out of the nucleus
      • Translation: decodes genetic messages to make proteins

    DNA Replication

    • DNA replication is the doubling process of DNA molecules
      • The parent molecule unwinds and two new daughter strands are built based on base pairing rules.

    DNA Replication (location)

    • A cell copies its DNA before mitosis or meiosis
    • DNA replication takes place in the nucleus during interphase
    • DNA repair mechanisms and proofreading processes correct most replication errors

    DNA Replication Importance

    • Genetic inheritance: ensures that a complete set of genetic instructions is given to each daughter ell when a cell divides.
    • Cell growth and repair: is essential for cell growth, tissue repair and maintenance.
    • Cell division: is a pre-requisite for cell division so that new cells have an identical copy of the genetic material.

    Steps in DNA Replication

    • Step 1: Replication Fork Formation
      • DNA strands are separated by DNA helicase which disrupts the hydrogen bonds
      • The replication fork is the “Y” shaped region where replication takes place.
      • Topoisomerase breaks, untwists and reconnects the DNA ahead of the replication fork
    • Step 2: Primer Binding
      • A short RNA piece (primer) attaches to the 3’ end of the leading strand
    • Step 3: Elongation
      • DNA polymerase adds DNA nucleotides to the 3’ end of the new strand
      • The leading strand is replicated continuously in the 5’ to 3’ direction

    DNA Transcription

    • DNA is transcribed to RNA, which is most often single-stranded
    • RNA uses uracil (U) instead of thymine (T) and ribose instead of deoxyribose
    • RNA polymerase adds nucleotides to transcripts

    Steps in Transcription

    • Step 1: Initiation
      • Begins when RNA polymerase binds to the gene’s promoter region
      • The enzyme then can “read” bases in one of the DNA strands
    • Step 2: Elongation
      • mRNA strand made by adding nucleotides using complementary base pairs
    • Step 3: Termination
      • RNA polymerase encounters a stop sequence and the mRNA strand detaches from the DNA

    Translation

    • The information carried by mRNA is decoded into a sequence of amino acids, resulting in a polypeptide chain that folds into a protein

    Translation (RNA)

    • rRNA (ribosomal RNA) and tRNA (transfer RNA) are used to translate the sequence of base triplets in mRNA into a sequence of amino acids

    Translation

    • mRNA codons are deciphered and a specific protein molecule is synthesized
    • Ribosomes are the sites for translation
      • They contain four rRNA molecules and 80 proteins, organized into two subunits,
      • Each subunit is composed of 65% rRNA and 35% protein, with the active site located in the ribosomal subunit,
      • The active site contains primarily rRNA which gives it the impression of being a ribozyme,
      • mRNA binds to the small subunit of the ribosome.

    Steps of Translation

    • Initiation: tRNA attaches to the P site of a small ribosomal subunit
    • Elongation: Another tRNA attaches itself to the A site. A dipeptide is formed under the influence of peptidyl transferase.
    • Termination: The polypeptide continues to grow via translocation until a stop codon is encountered.
    • Post-translational processing: The protein is rendered fully functional.

    mRNA - The Messenger

    • mRNA carries protein-building information to ribosomes and tRNA for translation
    • A codon is a sequence of three mRNA nucleotides that code for a specific amino acid.
      • The order of codons determines the order of amino acids in a polypeptide chain

    Genetic Code

    • There are 64 possible mRNA codons (triplets), some of which code for the same amino acid.
    • Some are start and stop codons:
      • AUG is the start codon for methionine
      • UAA, UAG, and UGA are stop codons

    Genetic Information

    • Genetic information is processed from DNA to mRNA to an amino acid sequence

    Protein Synthesis

    • Proteins are synthesized by ribosomes

    Mutation

    • A mutation is a change in the DNA sequence of an organism
    • Mutations can result from errors in DNA replication, exposure to mutagens or viral infections.

    Mutations (Types)

    • Germ cell mutations can be passed on to future generations and are important driving forces in evolution.
    • Somatic mutations are not passed down to the next generation, but are passed to all other somatic cells derived from it.

    DNA Structure

    • DNA is stable under alkaline conditions.
    • The deprotonated 2’ hydroxyl group acts as a nucleophile, but DNA lacks this group.
    • The phosphorus atom is the target of nucleophilic attack in DNA.
    • Nucleic acids have hierarchical levels of structure: primary, secondary, and tertiary.
    • Primary structure is defined by the nucleotide sequence and covalent bonds.
    • Secondary structure is the regular, stable structure common to all nucleic acids.
    • Tertiary structure involves the complex folding of large nucleic acids, such as chromosomes, tRNA, and rRNA.

    DNA Double Helix

    • The amounts of adenine (A), thymine (T), guanine (G), and cytosine (C) in a DNA molecule helped determine its three-dimensional structure.
    • The amounts of A and T are always equal.
    • The amounts of C and G are always equal.
    • Human DNA contains 30% adenine, 30% thymine, 20% guanine, and 20% cytosine.

    Watson and Crick Model of DNA

    • Two polynucleotide strands form DNA, running anti-parallel to each other.
    • One strand runs from 5’ to 3’, while the other runs from 3’ to 5’.
    • The sugar-phosphate backbone is on the outside of the helix.
    • Hydrophobic bases are on the inside.
    • The two strands are connected by hydrogen bonding between base pairs.
    • Adenine pairs with thymine via two hydrogen bonds, making this bond easier to separate.
    • Cytosine pairs with guanine via three hydrogen bonds, making this bond harder to separate.

    DNA Helix Features

    • DNA has a right-handed double helix structure.
    • The diameter of the helix is 20 Å.
    • There are 3.4 Å per base and 10.5 bases per helical turn, resulting in a 36 Å per turn helical structure.

    DNA Stability

    • The negatively charged phosphate groups in the backbone provide stability.
    • Van der Waals forces between stacked base pairs contribute to stability.
    • Higher GC content leads to a more stable DNA molecule.

    DNA Forms

    • Three DNA forms exist: A, B, and Z.
    • The B form is the most stable, right-handed double helix with the Watson-Crick structure. It is the predominant form in physiological conditions.
    • The A form is a right-handed double helix with a wider turn, favored in solutions lacking water.
    • The Z form is a left-handed helix with a zigzag appearance, longer and slender than the other forms.

    Base Pairing

    • A pyrimidine always pairs with a purine.
    • This fit is favored inside the DNA double strand.
    • Hydrogen bonding is most favorable in A–T and G–C pairs.
    • A–T and G–C pairing is called complementary.

    Chargaff’s Rule

    • The content of adenine equals the content of thymine.
    • The content of guanine equals the content of cytosine.
    • This allows prediction of base composition in a DNA sample by examining only one base.

    Major and Minor Grooves

    • The major groove occurs where the backbones are far apart.
    • The minor groove occurs where the backbones are close together.

    DNA Denaturation

    • Separating the two strands requires destroying/cutting the hydrogen bonds, a process known as DNA denaturation.
    • Denaturation causes the destruction of hydrogen bonding, transitioning DNA from double-stranded to single-stranded.

    Central Dogma of Molecular Biology

    • DNA is transcribed into RNA, which is then translated into protein.
    • The processes involved in the transfer of genetic information include replication, transcription, and translation.
    • Replication creates identical copies of DNA.
    • Transcription reads genetic messages and carries them out of the cell nucleus to the ribosomes for protein synthesis.
    • Translation decodes genetic messages to make proteins.

    DNA Replication

    • The doubling process of DNA molecules.
    • The parent molecule unwinds, and two new daughter strands are built based on base pairing rules.

    Location of DNA Replication

    • DNA replication occurs in the nucleus of a cell during interphase, before mitosis or meiosis.
    • Most replication errors are corrected by DNA repair mechanisms and proofreading.

    Importance of DNA Replication

    • Transposable elements are segments of DNA that can insert themselves anywhere in a chromosome.
    • Spontaneous mutations are uncorrected errors in DNA replication.
    • Harmful environmental agents like ionizing radiation and UV can also cause mutations.

    Types of Mutations

    • Point mutations involve replacement of one base with another.
    • Frame-shift mutations occur when a base is added or removed from the sequence.

    Point Mutation Types

    • Substitution mutations replace a single nucleotide with another.
    • Missense mutations result in a different amino acid being incorporated into the protein, potentially altering its function.
    • Silent mutations do not affect the amino acid sequence, resulting in no change to the protein.
    • Nonsense mutations introduce a premature stop codon, leading to a truncated and often nonfunctional protein.

    Other Mutation Types

    • Deletion mutations remove a section of DNA, potentially disrupting gene function.
    • Insertion mutations add one or more nucleotides to the DNA sequence, also disrupting the reading frame and leading to nonfunctional proteins.
    • Duplication mutations create extra copies of specific genes or sequences.

    Single-Gene Disorders

    • Cystic fibrosis affects the lungs, pancreas, and other organs due to mutations in the CFTR gene.
    • Sickle cell anemia is a blood disorder caused by mutations in the HBB gene, affecting hemoglobin.
    • Huntington's disease is a neurodegenerative disorder resulting from mutations in the HTT gene.
    • Hemophilia is a bleeding disorder due to mutations in the F8 or F9 genes, affecting clotting factors.
    • Tay-Sachs disease is a fatal genetic disorder affecting the nervous system due to mutations in the HEXA gene.

    Chromosome Disorders

    • Down Syndrome is caused by an extra copy of chromosome 21.
    • Turner Syndrome affects females with a missing or partially missing X chromosome.
    • Klinefelter Syndrome affects males with an extra X chromosome.
    • Prader-Willi Syndrome is characterized by intellectual disability, obesity, and behavioral problems, caused by a deletion on chromosome 15.
    • Angelman Syndrome involves intellectual disability, seizures, and a happy demeanor, also caused by a deletion on chromosome 15.

    Genetic Engineering

    • Genetic engineering intentionally changes an organism's DNA to alter its traits.
    • Recombinant DNA is DNA containing genetic material from two different organisms.

    PCR (Polymerase Chain Reaction)

    • A laboratory technique used to amplify DNA sequences.

    Viruses

    • Minute disease-causing agents with an outer protein coat.
    • They can only reproduce by invading host cells.
    • They cause host cells to produce more viruses, disrupting normal cell function.
    • Viruses attack bacteria, plants, animals, and humans.
    • Many human diseases are caused by viruses.
    • Viruses attach to the host cell surface.
    • An enzyme in the virus breaks down the cell membrane, creating a hole.
    • The virus then injects its DNA or RNA into the host cell.
    • Viral nucleic acid is replicated, producing hundreds of new viruses.

    Vaccinations

    • A preparation containing an inactive or weakened form of a virus.
    • Antibodies produced against inactive viral or bacterial envelopes can also kill naturally occurring viruses or bacteria.

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    Description

    Test your knowledge on nucleotides and nucleic acids, including their roles in metabolism and genetic information storage. This quiz covers the functions of DNA and various types of RNA, emphasizing protein synthesis and genetic regulation.

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