Central Dogma and DNA Replication
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Questions and Answers

What is the term used for the process of copying the genetic code into RNA?

  • Translocation
  • Translation
  • Transcription (correct)
  • Replication

    • Which strand of DNA serves as the template during the transcription process?

  • Antisense strand (correct)
  • Coding strand
  • Leading strand
  • Sense strand

    • Which enzyme is primarily responsible for synthesizing RNA during transcription?

  • RNA Polymerase III
  • RNA Polymerase I
  • RNA Polymerase II (correct)
  • DNA Polymerase

    • What is the function of the TATA Box in the transcription process?

    <p>To facilitate the binding of RNA Polymerase II</p> Signup and view all the answers

    Which components assist RNA Polymerase II in binding to the TATA Box during transcription initiation?

    <p>General transcription factors</p> Signup and view all the answers

    Which transcription factor is the first to bind to the TATA box?

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

    What role does TFIIH perform in the pre-initiation complex?

    <p>Acts as a helicase to split open the promoter</p> Signup and view all the answers

    How does TFIIF assist in the transcription process?

    <p>Facilitates the binding of RNA Polymerase II on the promoter</p> Signup and view all the answers

    In which direction does the pre-mRNA strand run during elongation?

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

    Which component of TFIIH has kinase activity?

    <p>7 subunits that do not use ATP</p> Signup and view all the answers

    What is the function of the start codon AUG in protein synthesis?

    <p>It codes for the amino acid methionine.</p> Signup and view all the answers

    What does aminoacyl synthetase do in the process of translation?

    <p>It binds the amino acid to the tRNA.</p> Signup and view all the answers

    Which process describes the transfer of the amino acid chain to water during termination?

    <p>Peptidyl transfer</p> Signup and view all the answers

    What happens to the ribosome after it reaches a stop codon?

    <p>It detaches from the mRNA and splits into subunits.</p> Signup and view all the answers

    During which phase does the ribosome slide towards the next codon and free the A-site?

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

    What role does the tRNA anticodon play in the translation process?

    <p>It complexes with the mRNA codon.</p> Signup and view all the answers

    What occurs when the levels of tryptophan decrease in the tryptophan operon system?

    <p>The corepressor releases the aporepressor</p> Signup and view all the answers

    Which of the following components is NOT involved in the termination phase of translation?

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

    How does gene regulation assist eukaryotic cells in growing and developing?

    <p>By helping cells manage external environmental changes</p> Signup and view all the answers

    Which statement about transcription factors is false?

    <p>Transcription factors bind to the operator to initiate transcription</p> Signup and view all the answers

    What is formed when the second amino acid is bound to methionine?

    <p>A peptide bond</p> Signup and view all the answers

    What happens to transcription factors when they are not required in the nucleus?

    <p>They remain in the cytoplasm</p> Signup and view all the answers

    What regulates the ability of transcription factors to bind to DNA?

    <p>The degree of multimerization and DNA-binding domain alterations</p> Signup and view all the answers

    Which of the following best describes the relationship between eukaryotic genes required for enzyme synthesis?

    <p>They may be located far apart on the same DNA or in different DNAs</p> Signup and view all the answers

    What role does phosphorylation play in the regulation of transcription factors?

    <p>It allows transcription factors to enter the nucleus</p> Signup and view all the answers

    Which process is NOT involved in the regulation of transcription factors in eukaryotes?

    <p>Regulation of teleomerase activity</p> Signup and view all the answers

    What role do transcription repressors play in mRNA production?

    <p>They bind to mRNA and regulate where spliceosomes cut.</p> Signup and view all the answers

    What is the main function of micro RNAs (miRNAs) in gene regulation?

    <p>To determine the fate of untranslatable mRNAs.</p> Signup and view all the answers

    Which scenario leads to the inhibition of translation in a cell?

    <p>Insufficient nutrients, particularly amino acids.</p> Signup and view all the answers

    How do miRNAs affect mRNAs with complementary sequences?

    <p>They lead to the destruction of the mRNA.</p> Signup and view all the answers

    What does the phosphorylation of eIFs result in?

    <p>Inhibition of translation.</p> Signup and view all the answers

    In differential mRNA splicing, what determines the combination of exons included in the final mRNA?

    <p>Regulatory protein binding to the mRNA.</p> Signup and view all the answers

    What is one way proteins can be regulated even after translation has occurred?

    <p>Through the process of phosphorylation.</p> Signup and view all the answers

    Which statement accurately describes the effect of partially complementary miRNAs on mRNAs?

    <p>They prevent the translation of the mRNA.</p> Signup and view all the answers

    What role does ubiquitination play in cellular protein management?

    <p>It signals proteins for degradation at the proteasome.</p> Signup and view all the answers

    What happens to the amino acids released from protein degradation?

    <p>They are recycled for new protein translation.</p> Signup and view all the answers

    Under what circumstance does ubiquitination typically occur?

    <p>When proteins are not utilized for an extended period.</p> Signup and view all the answers

    Which type of gene is always active in maintaining cellular functions?

    <p>Constitutive genes</p> Signup and view all the answers

    What characterizes facultative genes in a cell?

    <p>They can be turned on or off based on the cell's needs.</p> Signup and view all the answers

    What is the primary function of the proteasome in the ubiquitination process?

    <p>Degrading tagged proteins.</p> Signup and view all the answers

    Which statement regarding protein persistence is true?

    <p>Ubiquitination decreases the lifespan of proteins in the cell.</p> Signup and view all the answers

    Which component is involved in the recycling of amino acids during protein turnover?

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

    Study Notes

    Central Dogma and Molecular Genetics

    • The central dogma describes the flow of genetic material in organisms.
    • DNA replicates to produce new DNA.
    • DNA undergoes transcription to create RNA.
    • RNA undergoes translation to form proteins.
    • RNA can also produce DNA via reverse transcription.

    Molecular Mechanisms of DNA Replication

    • DNA replication is vital for maintaining the chromosome number in cell generations.

    • This guarantees identical genetic material in all body cells, excluding gametes.

    • The process in eukaryotes is detailed, followed by a comparison with prokaryotic replication.

    • Initiation:

      • DNA helicase unwinds the parental double helix.
      • Single-strand binding proteins stabilize the unwound DNA.
      • Topoisomerase relieves the tightening of the supercoil.

    • Elongation:

      • DNA polymerase adds complementary nucleotides in a 3' to 5' direction.
      • Leading strand synthesis is continuous (5' to 3').
      • Lagging strand synthesis is discontinuous, forming Okazaki fragments (3' to 5').
      • RNA primers are synthesized by primase and extended by DNA polymerase.
      • DNA ligase joins Okazaki fragments.

    • Termination:

      • DNA ligase joins Okazaki fragments.
      • Replication bubbles meet.
      • Replication is considered semi-conservative.

    Molecular Mechanisms of Gene Expression

    • Genes hold blueprints for building organisms via protein synthesis.
    • Polypeptide chains, formed from amino acids, comprise proteins.
    • Gene expression involves transcription and translation.
    • Eukaryotic gene expression is discussed initially, followed by a comparison with prokaryotic gene expression after laboratory work.

    Transcription

    • Initiation:

      • The DNA strand used for transcription is the sense strand; the complementary strand is the antisense strand.
      • Transcription factors (e.g., TFIID, TFIIA, TFIIB, TFIIE, TFIIH, TFIIF).
      • Pre-initiation complex formation involving TBP helps to bind to the TATA box.
      • Open complex formation: unwinding and RNA polymerase II binding.

    • Elongation:

      • RNA polymerase II adds RNA nucleotides to the growing RNA chain according to the DNA template.
      • New RNA is synthesized using the antisense strand as a template and in a 5’ to 3’ direction.
      • Formation of pre-mRNA transcript and the formation of 5' capping.

    • Termination

      • mRNA polymerase reaches the terminal region and interacts with proteins
      • Cleavage, stimulation factors (CstFs), cleave the pre-mRNA and separate it from RNA polymerase II.
      • Poly(A) tail is added (AAUAAA sequence)
      • RNA is processed further to form mRNA transcript.

    Reverse Transcription

    • Retroviruses use reverse transcription, an RNA-driven DNA synthesis.
    • Viral RNA serves as a template.
    • A single-stranded DNA is formed.
    • Complimentary DNA strand is formed.
    • Numerous copies of viral RNA and proteins are made.

    Gene Regulation (Prokaryotes)

    • Genes aren't expressed simultaneously.
    • Operon hypothesis (Jacob and Monod) describes the process.
    • Operon: a system of adjacent structural genes (cistrons).
    • Operator: controls transcription.
    • Promoter: RNA polymerase binding site.
    • Regulatory gene: codes for repressor protein.

    Gene Regulation (Eukaryotes)

    • Gene expression is controlled by external cues as cells develop.
    • Environmental cues are necessary for correct development.
    • Transcription factors (TF): molecules that bind to promoters to initiate transcription.
    • Regulation occurs at several stages:
      • Nuclear localization
      • DNA-binding
      • Activator proteins: enhance transcription.
      • Repressor proteins: inhibit transcription.
      • Regulation after transcription (mRNA processing).
      • Regulation of translation (e.g., phosphorylation)

    Regulation of Translation

    • The cell controls protein production if resources are insufficient.
    • ElFs are involved in translation and they are phosphorylated to be deactivated if resources are insufficient

    Regulation After Translation

    • Proteins are regulated after translation, through phosphorylation and ubiquitination.
    • Enzymes associated with Phosphorylation and Ubiquitination are used to influence protein activity.

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    Molecular Genetics: Central Dogma & DNA Replication Notes PDF

    Description

    Explore the central dogma of molecular genetics and the intricate mechanisms of DNA replication. Understand how DNA is transcribed into RNA and translated into proteins, along with the replication process in eukaryotic and prokaryotic cells. This quiz highlights key processes and enzymes involved in genetic material flow.

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