Mutations and Genetic Variation
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Questions and Answers

What is the main function of the CFTR protein?

  • Regulating blood sugar levels
  • Maintaining the balance of salt and water on cell surfaces (correct)
  • Storing genetic information
  • Producing antibodies to fight infections

    • Why did the doctor ask for CTT deletion?

  • Because it's the most common mutation in the CFTR gene
  • Because it's a frameshift mutation
  • Because it causes a significant loss of function in the CFTR protein (correct)
  • Because it's a spontaneous mutation

    • What type of mutation is the CTT deletion?

  • Non-frameshift mutation
  • Chromosomal mutation
  • Frameshift mutation (correct)
  • Point mutation

    • Why is PCR technique suitable for detecting CTT deletion?

    <p>Because it's sensitive to small DNA changes</p> Signup and view all the answers

    What type of mutation is shown in Azad's β globin gene?

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

    What is one of the causes of mutations?

    <p>Spontaneous mutations</p> Signup and view all the answers

    What is a mutation?

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

    What can result from mutations that occur during DNA replication?

    <p>A protein with an abnormal amino acid sequence</p> Signup and view all the answers

    What is a source of genetic variation?

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

    What is the result of a mutation in a gene?

    <p>A mutant allele</p> Signup and view all the answers

    What can mutations cause?

    <p>Genetic diseases, cell death, and changes in enzyme activity</p> Signup and view all the answers

    What is a mutant phenotype?

    <p>A phenotype that differs from the common or wild type phenotype in the population</p> Signup and view all the answers

    What type of mutation occurs when there is a change in a single nucleotide base?

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

    What is a mutant allele?

    <p>An allele that differs from the common allele in the population</p> Signup and view all the answers

    What is the effect of a silent mutation?

    <p>It does not alter the amino acid specified</p> Signup and view all the answers

    What type of mutation occurs when a nucleotide is inserted or deleted in the DNA sequence?

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

    What is the relationship between a mutation and a mutant?

    <p>A mutation causes a mutant phenotype</p> Signup and view all the answers

    What is the result of a nonsense mutation?

    <p>It introduces a stop codon</p> Signup and view all the answers

    What type of mutation does not change the reading frame?

    <p>Non-frameshift mutation</p> Signup and view all the answers

    What happens when there is an insertion or deletion of nucleotides other than 3 or multiples of 3?

    <p>The reading frame shifts</p> Signup and view all the answers

    What can point mutations in non-coding regions of a gene affect?

    <p>Protein binding sites, promoter sequences, and splice sites</p> Signup and view all the answers

    What is the name of the type of mutation that replaces one amino acid with another?

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

    What type of mutations are inherited and transmitted to offspring?

    <p>Germline mutations</p> Signup and view all the answers

    What is the consequence of failure in DNA repair?

    <p>Disease occurrence</p> Signup and view all the answers

    What is the frequency of mispairing during eukaryotic replication?

    <p>One mispairing per 109 to 1012 nucleotides</p> Signup and view all the answers

    What is the primary function of DNA repair mechanisms?

    <p>To identify and correct DNA damage</p> Signup and view all the answers

    When do proofreading and DNA repair occur?

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

    What is the enzyme responsible for proofreading during DNA replication?

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

    What is the result of combined effects of vertical and horizontal transmission of induced mutations?

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

    What is the frequency of mutations in normal metabolic activities?

    <p>Very frequent</p> Signup and view all the answers

    What is removed by the excision endonuclease enzyme in nucleotide excision repair?

    <p>The entire nucleotide</p> Signup and view all the answers

    What is the result of a defect in the nucleotide excision repair mechanism?

    <p>Increased risk of cancer</p> Signup and view all the answers

    What is the purpose of the DNA mismatch repair system?

    <p>To recognize and repair DNA replication errors</p> Signup and view all the answers

    What is the name of the autosomal recessive disorder caused by a defect in nucleotide excision repair?

    <p>Xeroderma Pigmentosum (XP)</p> Signup and view all the answers

    What is the type of bond cleaved by the glycosylase enzyme in base excision repair?

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

    What is the name of the syndrome caused by a mutation in the MLH1 gene?

    <p>Hereditary nonpolyposis colorectal cancer (HNPCC)</p> Signup and view all the answers

    What type of damage is corrected by nucleotide excision repair?

    <p>Both A and B</p> Signup and view all the answers

    How do individuals with Xeroderma Pigmentosum reduce their risk of skin cancer?

    <p>By avoiding sunlight</p> Signup and view all the answers

    Study Notes

    Mutations and Genetic Variation

    • A mutation is a permanent, heritable change in an organism's DNA base sequence
    • Mutations can result from damage to DNA molecules or unrepaired errors during replication
    • They can cause genetic diseases, cell death, or changes in enzyme activity, nutritional requirements, antibiotic susceptibility, and other cellular properties
    • Mutations are a source of genetic variation and can lead to evolution
    • Not all mutations are bad; some can be beneficial

    Types of Mutations

    • Small mutations: change in nucleotide sequence of a single gene
      • Substitutions (point mutations): a single base change
        • Silent: does not alter the amino acid specified
        • Missense: replaces one amino acid with another
        • Nonsense: changes the amino acid specified to a stop codon
      • Insertions, deletions, and frameshift mutations: addition or removal of one or more bases
        • Non-frameshift: insertion or deletion of 3 nucleotides (or multiples of 3)
        • Frameshift: insertion or deletion of nucleotides other than 3 or multiples of 3
    • Large-scale mutations: abnormal number of chromosomes or chromosomal structure (to be covered in next lecture)

    Causes of Mutations

    • Spontaneous mutations
    • Horizontal transmission
    • Gametes (germline mutations): inherited and transmitted to offspring
    • Environmental factors: can cause DNA damage and mutations

    DNA Repair Mechanisms

    • Cells have mechanisms to check and repair genetic code during and after DNA replication
    • Failure of DNA repair can have serious consequences, leading to disease
    • Types of repair mechanisms:
      • Excision repair
        • Base excision repair
        • Nucleotide excision repair
      • Mismatch repair
    • Enzymes involved in repair mechanisms:
      • DNA polymerase (proofreading)
      • Glycosylase (base excision repair)
      • Excision endonuclease (nucleotide excision repair)
      • MLH1 and other proteins (mismatch repair)

    DNA Damage, Repair, and Cancer

    • DNA damage can occur due to normal metabolic activities or environmental factors
    • Failure of DNA repair can lead to mutations and cancer
    • Examples of diseases caused by defects in DNA repair mechanisms:
      • Xeroderma pigmentosum (XP): defect in nucleotide excision repair
      • Hereditary nonpolyposis colorectal cancer (HNPCC): defect in mismatch repair

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    Mutation Lecture Slides PDF

    Description

    Understand the concept of mutations, their causes, effects, and role in genetic variation and evolution. Learn how mutations can lead to genetic diseases or beneficial changes.

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