Meiosis II Overview
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Questions and Answers

What does gene amplification primarily involve?

  • Increase in the number of genes for a certain function (correct)
  • Decrease in the number of genes for a certain function
  • Silencing of gene expression
  • Rearrangement of gene units
  • Which drug is mentioned as a cause for gene amplification?

  • Cyclophosphamide
  • Doxorubicin
  • Aspirin
  • Methotrexate (correct)
  • How does methotrexate exert its effect on cancer cells?

  • By promoting gene rearrangement
  • By increasing the number of acetylated histones
  • By inhibiting dihydrofolate reductase gene (correct)
  • By enhancing DNA synthesis
  • What is the main result of gene diminution during cell maturation?

    <p>Decrease in gene size or number</p> Signup and view all the answers

    Which of the following describes gene rearrangement?

    <p>Recombination of different gene units</p> Signup and view all the answers

    What role do acetylated compounds play in epigenetic regulation?

    <p>They reduce positive charges on histones.</p> Signup and view all the answers

    Which part of immunoglobulin genes is primarily involved in gene rearrangement?

    <p>Variable regions</p> Signup and view all the answers

    What is the primary effect of reducing DNA packing around histones?

    <p>Enhanced accessibility for transcription</p> Signup and view all the answers

    What is the main difference in the number of divisions between mitosis and meiosis?

    <p>Mitosis has one division; meiosis has two.</p> Signup and view all the answers

    During which stage of meiosis II do the chromatids move toward opposite poles?

    <p>Anaphase II</p> Signup and view all the answers

    What type of daughter cells are produced at the end of meiosis?

    <p>Haploid cells</p> Signup and view all the answers

    Which feature distinguishes crossing over from mitosis?

    <p>It involves exchange of genetic materials.</p> Signup and view all the answers

    What type of chromosomes determine the sex of an organism?

    <p>Sex chromosomes</p> Signup and view all the answers

    What is the first step in karyotyping?

    <p>Add heparin to a blood sample.</p> Signup and view all the answers

    Which type of chromosome has the centromere located at the very end?

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

    What is the primary outcome of meiosis in terms of genetic diversity?

    <p>Leads to genetic variation.</p> Signup and view all the answers

    Which part of the tRNA is responsible for attaching to a specific amino acid?

    <p>Acceptor arm</p> Signup and view all the answers

    What is the function of small nuclear RNA (snRNA)?

    <p>Removing introns from pre-mRNA</p> Signup and view all the answers

    How are DNA viruses, like Hepatitis B, less prone to mutations compared to RNA viruses?

    <p>They have proofreading mechanisms</p> Signup and view all the answers

    What is a unique feature of tRNA's anticodon loop?

    <p>It has hypoxanthine that pairs with several bases</p> Signup and view all the answers

    What is the primary role of ribosomal RNA (rRNA) in cells?

    <p>Forming the structure of ribosomes and protein synthesis</p> Signup and view all the answers

    What characterizes apoptosis?

    <p>It is programmed cell death</p> Signup and view all the answers

    Which type of RNA is primarily involved in the synthesis of histones needed for mRNA processing?

    <p>Group II small nuclear RNA</p> Signup and view all the answers

    What is a main reason why RNA viruses are more difficult to vaccinate against?

    <p>They undergo high mutation rates without proofreading</p> Signup and view all the answers

    What is the purpose of denaturation in the polymerase chain reaction (PCR)?

    <p>To break hydrogen bonds in double-stranded DNA.</p> Signup and view all the answers

    Which enzyme is primarily used during the elongation phase of PCR?

    <p>Taq polymerase</p> Signup and view all the answers

    How can PCR be applied in the diagnosis of genetic diseases?

    <p>By enabling the detection of deleterious mutations in target genes.</p> Signup and view all the answers

    What is one of the major advantages of using PCR for detecting infectious diseases?

    <p>It is faster and more reliable than other diagnostic tools.</p> Signup and view all the answers

    Why can PCR be considered a fabulous diagnostic tool?

    <p>It can detect both genetic and infectious diseases.</p> Signup and view all the answers

    What aspect of genomic DNA does PCR target when analyzing noncoding sequences?

    <p>Noncoding sequences are not involved in protein synthesis.</p> Signup and view all the answers

    Which step includes binding of primers in the PCR process?

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

    What does the completion of the genome sequencing project enable in PCR applications?

    <p>Synthesis of primers for any region of interest.</p> Signup and view all the answers

    What characterizes double minute (DM) chromosomes?

    <p>They are minichromosomes without centromeres.</p> Signup and view all the answers

    Which of the following describe functions of proteins produced by tumor suppressor genes?

    <p>Facilitating DNA repair</p> Signup and view all the answers

    What does the two-hit hypothesis state regarding tumor suppressor genes?

    <p>Both alleles must be mutated for loss-of-function.</p> Signup and view all the answers

    How do oncogenes differ from tumor suppressor genes?

    <p>Oncogenes lead to gain-of-function mutations.</p> Signup and view all the answers

    What is a result of mutations in tumor suppressor genes?

    <p>Reduction in DNA repair mechanisms.</p> Signup and view all the answers

    What is the role of ATP-binding cassette (ABC) gene family in cells?

    <p>They transport molecules including drugs.</p> Signup and view all the answers

    Which of the following statements about tumor suppressor genes is incorrect?

    <p>They always cause cancer with mutations.</p> Signup and view all the answers

    What can overexpression of certain ABC transporters lead to?

    <p>Resistance to some drug therapies.</p> Signup and view all the answers

    Study Notes

    Meiosis II

    • Meiosis II resembles mitosis and consists of prophase II, metaphase II, anaphase II, and telophase II.
    • Prophase II: Formation of the mitotic spindle begins.
    • Metaphase II: 23 d-chromosomes align at the equatorial plane.
    • Anaphase II: Chromatids move towards opposite poles.
    • Telophase II results in four daughter cells, each containing 23 s-chromosomes.

    Comparison: Mitosis vs. Meiosis

    • Mitosis occurs in somatic cells, while meiosis occurs in germ cells.
    • Mitosis involves one division and produces two genetically identical diploid cells.
    • Meiosis undergoes two divisions, yielding four genetically diverse haploid cells.
    • In meiosis, crossing over occurs, allowing gene exchange, whereas mitosis has no crossing over.

    Chromosome Classification

    • Autosome: 22 pairs that control somatic traits.
    • Sex chromosomes: 1 pair that determines biological sex.
    • Centromere position:
      • Metacentric: Centered.
      • Submetacentric: Between center and end.
      • Acrocentric: Near one end, with one long arm and one short.
      • Telocentric: At the end, not present in humans, but in mice.

    Karyotyping

    • Definition: Study of chromosomes by number and type, based on centromere position and length.
    • Steps for karyotype analysis include adding heparin to the blood, centrifuging to separate WBCs, stimulating division, halting division with colchicine, and using a hypotonic solution to disperse chromosomes.

    RNA Functions

    • tRNA (Transfer RNA): Transfers amino acids during protein synthesis, containing:

      • Acceptor arm for amino acid attachment.
      • Anticodon loop for mRNA interaction.
      • Dihydrouracil and pseudouridine in various loops.
    • rRNA (Ribosomal RNA): Forms ribosome subunits (40S and 60S) responsible for protein synthesis.

    • Small nuclear RNA: Involved in mRNA processing and intron excision, including groups that remove introns and those that help synthesize histones.

    Viruses and Nucleic Acids

    • DNA viruses (e.g., Hepatitis B) have proofreading capabilities, making them less prone to mutations, thus easier to vaccinate against.
    • RNA viruses (e.g., HIV, Hepatitis C) lack proofreading, resulting in higher mutation rates and challenges in vaccine development.

    Apoptosis

    • Apoptosis refers to programmed cell death.
    • Gene expression is regulated chromosomally via amplification, diminution, rearrangement, and epigenetic mechanisms.

    Drug Resistance

    • Methotrexate, used in cancer treatment, inhibits dihydrofolate reductase but can lead to gene amplification in cancer cells, causing drug resistance.

    Tumor Suppressor Genes

    • Prevent tumor development by regulating the cell cycle, growth, DNA repair, and apoptosis.
    • Loss-of-function mutations increase cancer risk, following the two-hit hypothesis where both gene alleles must be impaired for effects to be observed.

    Polymerase Chain Reaction (PCR)

    • PCR facilitates rapid evaluation of nucleic acids, essential for genetic disease diagnosis.
    • Steps include DNA denaturation, elongation using Taq polymerase, and repeated cycles for amplification.
    • Widely employed in detecting genetic disorders, infectious diseases, and forensic applications due to its sensitivity and reliability.

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    Description

    This quiz covers the key stages of Meiosis II, including Prophase II, Metaphase II, Anaphase II, and Telophase II. Understanding these stages is essential for grasping how daughter cells are formed from the original diploid cell, leading to four haploid cells. Test your knowledge on the similarities and differences between meiosis and mitosis.

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