Module 9 - Effects of Mutations I
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Questions and Answers

What type of mutation is responsible for the commonest mutation in cystic fibrosis known as ΔF508?

  • Missense mutation
  • Nonsense mutation
  • Frameshift mutation
  • In-frame deletion (correct)

    • What is the effect of the G542X mutation in cystic fibrosis patients?

  • The CFTR protein is not produced due to a stop codon (correct)
  • The CFTR protein is produced but is non-functional
  • The CFTR protein is made normally
  • The CFTR protein is produced at a reduced rate

    • What type of mutation is G551D in cystic fibrosis, and what does it specifically do?

  • Silent mutation that has no effect on CFTR protein
  • Missense mutation that alters CFTR functional efficiency (correct)
  • Nonsense mutation that prevents CFTR protein synthesis
  • Frameshift mutation that disrupts the entire protein structure

    • In the context of cystic fibrosis, what is the consequence of a recessive disorder caused by mutations in both alleles of a gene?

    <p>Symptoms occur only in individuals with two mutated alleles</p> Signup and view all the answers

    Which of the following statements about CFTR protein function is true regarding cystic fibrosis mutations?

    <p>Mutations can lead to CFTR protein reaching the cell surface but being dysfunctional</p> Signup and view all the answers

    When discussing carriers of cystic fibrosis, what best describes their genetic makeup?

    <p>They have one normal allele and one mutated allele</p> Signup and view all the answers

    What is the primary role of the CFTR protein in cells?

    <p>Transporting chloride ions across cell membranes</p> Signup and view all the answers

    Orkambi, a treatment for cystic fibrosis, consists of which two components?

    <p>Ivacaftor and Lumacaftor</p> Signup and view all the answers

    How does a deletion of nucleotides affect the function of a CFTR protein?

    <p>It prevents the protein from reaching the cell surface</p> Signup and view all the answers

    What is the total number of amino acids in the CFTR protein, as mentioned in the content?

    <p>1480</p> Signup and view all the answers

    What type of mutation is characterized by the replacement of one base pair with another?

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

    Which type of mutation does not alter the amino acid sequence?

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

    What occurs during a nonsense mutation?

    <p>A codon for an amino acid is changed to a stop codon</p> Signup and view all the answers

    What is the result of a frameshift mutation?

    <p>The amino acid sequence shifts due to changes in the reading frame</p> Signup and view all the answers

    Which mutation involves the insertion of base pairs?

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

    In which type of mutation does a stop codon change to a codon for an amino acid?

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

    What are the effects of point mutations?

    <p>A mixture of nonsense, synonymous, and missense effects</p> Signup and view all the answers

    What is the role of suppressive mutations?

    <p>They restore the correct amino acid sequence even if the nucleotide sequence is altered</p> Signup and view all the answers

    Which statement best describes insertion mutations?

    <p>They involve adding one or more base pairs to a gene</p> Signup and view all the answers

    What is a common result of deletion mutations?

    <p>Alteration of the reading frame and potentially nonfunctional proteins</p> Signup and view all the answers

    Which of the following does not characterize transversion mutations?

    <p>Purine to purine transition</p> Signup and view all the answers

    What term describes mutations like those found in cystic fibrosis?

    <p>Monogenic disorders</p> Signup and view all the answers

    What is one major reason mutations are significant in biological evolution?

    <p>They introduce new genetic variations into populations</p> Signup and view all the answers

    What is the significance of the G171V mutation in LDL-Receptor–Related Protein 5?

    <p>It correlates with decreased incidence of bone fractures.</p> Signup and view all the answers

    Which mutation is associated with individuals requiring more anesthesia?

    <p>Melanocortin 1 receptor mutation</p> Signup and view all the answers

    How does the DEC2-P384R mutation affect sleep patterns?

    <p>It increases the expression of Orexin.</p> Signup and view all the answers

    What is the primary outcome associated with the apolipoprotein A-I 'Milano' variant?

    <p>Reduction in cardiovascular disease risk.</p> Signup and view all the answers

    Which of the following statements about the MC1R mutation is correct?

    <p>It can cause red hair and fair skin.</p> Signup and view all the answers

    What does the LRP5 gene primarily regulate?

    <p>Bone density through Wnt signaling.</p> Signup and view all the answers

    Which benefit is least likely associated with the Natural Short Sleep mutation?

    <p>Lowered anxiety levels.</p> Signup and view all the answers

    How does the mutation in the apoAI contribute to cardiovascular health?

    <p>By reducing atherosclerotic lesions.</p> Signup and view all the answers

    Which feature characterizes human natural short sleepers?

    <p>They show no harmful effects despite shorter sleep.</p> Signup and view all the answers

    What is the main function of the orexin peptide in sleep regulation?

    <p>To encourage wakefulness.</p> Signup and view all the answers

    What is the primary distinction between genotype and phenotype in an organism?

    <p>Genotype describes the combined alleles of an organism, while phenotype refers to observable biological characteristics.</p> Signup and view all the answers

    How does haploinsufficiency affect an organism?

    <p>One defective gene copy can lead to a disease due to insufficient protein production.</p> Signup and view all the answers

    What type of genetic disorder exemplifies the effects of large deletion mutations?

    <p>Deletion of approximately 500 kb from the X chromosome.</p> Signup and view all the answers

    What is the consequence of having an unusual number of chromosomes in an organism?

    <p>Monosomy and trisomy can lead to various diseases.</p> Signup and view all the answers

    Which statement describes chromosome translocations?

    <p>They involve the exchange of segments between different chromosomes.</p> Signup and view all the answers

    In inherited diseases caused by mutant alleles, what role do carriers play?

    <p>Carriers do not express the disease but can pass the allele to offspring.</p> Signup and view all the answers

    What best describes monogenic disorders?

    <p>Inherited diseases caused by defects in single genes.</p> Signup and view all the answers

    Which example best illustrates a condition caused by haploinsufficiency?

    <p>Mandibulofacial Dysostosis Guion Almeida type due to EFTUD2 malfunction.</p> Signup and view all the answers

    What is the result of the Philadelphia chromosome's formation?

    <p>Uncontrolled cell division leading to leukemia.</p> Signup and view all the answers

    Which mutation type can lead to bone marrow failure and increased leukemia risk?

    <p>Monosomy, specifically of chromosome 7.</p> Signup and view all the answers

    Which of the following exemplifies the role of mutations in evolution?

    <p>Some mutations can enhance organismal fitness.</p> Signup and view all the answers

    What do mutations in diploid organisms typically imply about gene presence?

    <p>Each gene is represented by two copies in diploid organisms.</p> Signup and view all the answers

    What is the function of the CFTR gene in healthy individuals?

    <p>It regulates the production of mucus in various organs.</p> Signup and view all the answers

    Which genetic change is characterized by the presence of three copies of chromosome 21?

    <p>Trisomy.</p> Signup and view all the answers

    Study Notes

    Module 9 - Lecture 1: Effects of Mutations I

    • Topic: Effects of mutations on the information content of genes
    • Types of mutations: Point, insertion, deletion, frameshift, readthrough, and other mutations
    • Relevance: Mutations are crucial for evolution and organism diversity, but some cause disease
    • Illustrative example: Mutations in Cystic Fibrosis demonstrate the impact of mutations on gene product synthesis/activity
    • Point mutation: One base pair is replaced with another
      • Transition: Purine to purine (A to G) or pyrimidine to pyrimidine (T to C)
      • Transversion: Purine to pyrimidine (A or G to T or C) or vice versa
    • Insertion mutation: One or more base pairs are inserted into the DNA sequence
    • Deletion mutation: One or more base pairs are deleted from the DNA sequence
    • Inversion mutation: Two or more base pairs are excised and reinserted in the opposite orientation
    • Effects of point mutations on genes:
      • Synonymous mutation (silent mutation): No effect on the amino acid sequence, although it can occur in intergenic regions
      • Non-synonymous mutation (missense mutation): Changes the amino acid sequence
      • Nonsense mutation: Changes a codon for an amino acid into a stop codon
      • Readthrough mutation: Changes a stop codon to a codon for an amino acid

    Monogenic Disorders

    • Definition: Inherited diseases caused by defects in individual genes
    • Prevalence: About 6000 known monogenic disorders; estimated 10,000 in total
    • Common UK example: Cystic Fibrosis

    Effects of Mutations on the Cystic Fibrosis Gene

    • CFTR gene: Codes for the cystic fibrosis transmembrane regulator protein (CFTR)
      • Function: A chloride channel on the cell surface, crucial for regulating salt and water balance within and outside the cells
    • F508del mutation: The most common mutation in the UK (68% of cases)
      • Mechanism: Deletion of three nucleotides, removing the codon for phenylalanine (508th amino acid of the polypeptide)
      • Outcome: The CFTR protein is misfolded and cannot reach the cell surface, impaired function
    • G542X mutation: Second most common
      • Mechanism: A nonsense mutation, changing glycine (G) to a stop codon (X) at position 542
      • Outcome: Premature termination of the CFTR protein synthesis, leading to a non-functional protein
    • G551D mutation: Third most common
      • Mechanism: A missense mutation, changing glycine (G) to aspartic acid (D) at position 551
      • Outcome: A less severe impact on the CFTR protein function, but reduced function (4% of normal)

    Treatment for Cystic Fibrosis

    • Orkambi (combination of Ivacaftor and Lumacaftor): Effective in people with two copies of the F508del mutation
      • Ivacaftor (CFTR Potentiator): Increases the probability of the CFTR channel opening
      • Lumacaftor (CFTR Corrector): Improves the processing and trafficking of CFTR to the cell surface

    Resources

    • Reading material: Brown (specific chapters and pages), Alberts (specific chapters and pages)
    • Other resources: PDF files with Objectives, Terms, Questions and Answers, Further Study Module on Mutations and Human Diseases available on Blackboard

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    BIOL10221 2024 Molecular Biology Lecture Notes (Effects of Mutations) PDF
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    Description

    Explore the various effects of mutations on gene information content in this quiz. Learn about different types of mutations such as point, insertion, deletion, and their relevance to evolution and diseases like Cystic Fibrosis. Test your understanding of how these mutations impact gene product synthesis and activity.

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