DNA Repair Mechanisms
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DNA Repair Mechanisms

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Questions and Answers

What is primarily responsible for drug absorption in the body?

  • Receptors
  • Enzymes
  • Proteins (correct)
  • Transporters
  • How can genetic variation influence drug efficacy?

  • By increasing drug metabolism
  • By enhancing drug absorption
  • By decreasing drug toxicity
  • By altering protein structure (correct)
  • What is a potential outcome of a genetic mutation in terms of drug response?

  • Decreased metabolism of the drug
  • Altered protein function (correct)
  • Increased drug concentration in the bloodstream
  • Enhanced receptor sensitivity
  • In pharmacogenetics, what are the two main aspects of drug response being analyzed?

    <p>Efficacy and toxicity</p> Signup and view all the answers

    Which of the following is an example of a drug target affected by proteins?

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

    What primary function do proteins serve in pharmacokinetics?

    <p>Facilitating absorption</p> Signup and view all the answers

    What occurs when a protein's structure is altered due to genetic variation?

    <p>Altered drug response</p> Signup and view all the answers

    Which term describes the genetic impact on an individual’s response to drugs?

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

    What is one possible negative outcome of altered drug response due to genetic factors?

    <p>Lower efficacy</p> Signup and view all the answers

    What kind of proteins act as drug targets impacting pharmacodynamics?

    <p>Transporters and receptors</p> Signup and view all the answers

    Study Notes

    DNA Repair Mechanisms

    • Base alterations, such as cytosine deamination, can lead to abnormal bases like uracil.
    • Enzymes called glycosylases recognize and remove abnormal bases, creating an apyrimidinic site.
    • Double-strand breaks in DNA are induced by radiation or free radicals; traditional repair mechanisms are ineffective for these breaks.
    • Repair proteins can re-ligate DNA ends, potentially causing harmful errors, mutations, cancer, or immunodeficiency diseases.

    Genomic Variation

    • Genetic diversity exists within and between populations, influencing traits like skin color and disease susceptibility.
    • Variation arises from mutation, recombination, and natural selection.
    • Natural selection favors alleles providing selective advantages.
    • Genetic variations can alter phenotypes by affecting gene expression, protein function, or efficacy.

    Single-Nucleotide Polymorphisms (SNPs)

    • SNPs are single base pair changes, primarily from replication errors.
    • More frequent in noncoding regions due to selective pressure on coding domains.
    • Synonymous SNPs do not change amino acids, whereas nonsynonymous SNPs can lead to missense (amino acid substitution) or nonsense mutations (premature stop codon).
    • Nonsense mutations are more likely to be pathogenic; missense mutation effects depend on amino acid positioning and substitution nature.
    • SNPs in noncoding regions may influence gene expression, especially if located in regulatory areas.

    Protein Structures

    • Secondary structures, such as α-helices and β-sheets, form through intramolecular hydrogen bonding, minimizing steric repulsion.
    • Tertiary structure refers to the three-dimensional arrangement of a polypeptide, often revealing structural domains.

    Post-Translational Modifications (PTMs)

    • Glycosylation involves attaching carbohydrates, significant in eukaryotic proteins, particularly on cell surfaces.
    • γ-Carboxylation and β-hydroxylation are PTMs influencing blood coagulation by mediating calcium ion binding.
    • Sulfation, the addition of sulfate groups, enhances protein-protein interactions, while amidation, the conversion of a carboxyl group to an amide, stabilizes certain peptides.

    Genetic Contributions to Drug Response

    • Physicians often prescribe medications based on clinical signs and empirical data, with variability in drug effectiveness (30-60%).
    • Only 25% of cancer patients benefit significantly from treatments; many experience adverse effects without improved outcomes.
    • Genetic and environmental factors lead to inter-individual variability in drug responses, with genetics explaining 20-95% of pharmacokinetic differences.
    • Proteins play vital roles in drug absorption, metabolism, and action; genetic variations can alter protein function, stability, and structure, affecting drug efficacy or toxicity.

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    Description

    Explore the intricate processes of DNA repair, focusing on base excision repair and the handling of double-strand breaks. Understand how abnormal bases like uracil are recognized and removed from DNA, and learn about the effects of high-energy radiation on DNA integrity.

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