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Mutations and Genetic Variation
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Mutations and Genetic Variation

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@AmiableEuclid

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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    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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