Cytogenetics Techniques Overview
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Questions and Answers

What is the primary purpose of the post-hybridization washing step?

  • To enhance the visibility of the counter stain
  • To increase the temperature for better hybridization
  • To remove unbound or non-specifically bound probes (correct)
  • To incubate the cells overnight

    • At what temperature are the cells typically incubated during the conversion of double-stranded DNA to single-stranded DNA?

  • 25 degrees Celsius
  • 50 degrees Celsius
  • 37 degrees Celsius (correct)
  • 42 degrees Celsius

    • What is the role of the fluorescent-labeled probe?

  • To increase the temperature during incubation
  • To stain the cells for easier observation
  • To enhance the hybridization conditions
  • To emit light and indicate binding to the target DNA (correct)

    • What is the main goal after completing the washing technique?

    <p>To analyze hybridized sample abnormalities</p> Signup and view all the answers

    When analyzing the hybridized sample, what determines the patterns observed?

    <p>The fluorescent signals emitted by the probes</p> Signup and view all the answers

    In which step do scientists apply the counter stain?

    <p>After washing unbound probe DNA</p> Signup and view all the answers

    What biological materials can serve as target samples in this process?

    <p>Cells, tissue sections, and body fluids</p> Signup and view all the answers

    What must occur to the cells before the fluorescent probe can hybridize effectively?

    <p>They need to be incubated under specific conditions</p> Signup and view all the answers

    What is the primary function of probes when they hybridize with target DNA?

    <p>To emit light for visualization</p> Signup and view all the answers

    Which hapten is commonly used in indirect labeling for signal detection?

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

    What type of probe is designed to determine the presence or absence of specific sequences?

    <p>Locus-specific probes</p> Signup and view all the answers

    How are digoxigenin haptens detected?

    <p>With anti-digoxigenin antibodies</p> Signup and view all the answers

    What does the category of 'probes' refer to?

    <p>Broad classifications based on function</p> Signup and view all the answers

    Which example represents the application of probes in medical diagnostics?

    <p>Identification of BCR-ABL fusion in leukemia</p> Signup and view all the answers

    What causes a stronger green signal in DNA labeling?

    <p>Less target sequence for red probe binding</p> Signup and view all the answers

    What characteristic is NOT typically used to classify probes?

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

    What is the role of Cot-1 DNA in the labeling process?

    <p>To block repetitive sequences</p> Signup and view all the answers

    In terms of their function, what do locus-specific probes provide information about?

    <p>Specific genes or chromosomal locations</p> Signup and view all the answers

    What is the purpose of denaturation in the labeling process?

    <p>To separate double-stranded DNA into single strands</p> Signup and view all the answers

    What indicates a duplication in a DNA sample during the labeling process?

    <p>More copies of a DNA segment compared to the reference</p> Signup and view all the answers

    Why is repetitive DNA commonly found in telomere and centromere regions?

    <p>They provide structural stability to chromosomes</p> Signup and view all the answers

    What effect does the presence of unlabeled Cot-1 DNA have on red probes?

    <p>It reduces the efficiency of red probes</p> Signup and view all the answers

    What happens to the hydrogen bonds between complementary bases during denaturation?

    <p>They are broken, separating the strands</p> Signup and view all the answers

    How does a missing segment of DNA affect the strength of the red signal?

    <p>It diminishes the red signal strength</p> Signup and view all the answers

    What does a stronger red signal indicate in the context of DNA copy number?

    <p>Increased copy number of a DNA segment</p> Signup and view all the answers

    What will indicate a deletion in the test sample?

    <p>Increased green signal in the corresponding region</p> Signup and view all the answers

    When regions of DNA show equal copy numbers, what color signal is observed?

    <p>Yellow signal</p> Signup and view all the answers

    What contributes to a stronger red signal in the probe binding?

    <p>Multiple copies of the target sequence in the test sample</p> Signup and view all the answers

    How does a duplication affect the fluorescence signal interpretation?

    <p>It causes an increase in red signal intensity in multiple regions</p> Signup and view all the answers

    In fluorescence signal analysis, what does the presence of a green signal suggest?

    <p>A loss of one or more DNA segments</p> Signup and view all the answers

    Why is it important to analyze the fluorescence signals along chromosomes?

    <p>To identify variations in DNA copy numbers</p> Signup and view all the answers

    What does a stronger green signal correspond to in the context of DNA analysis?

    <p>Decreased presence of the target sequence</p> Signup and view all the answers

    What is the primary application of Array CGH?

    <p>To evaluate DNA copy number alterations in cancer</p> Signup and view all the answers

    How does Array CGH differ from traditional CGH?

    <p>Array CGH uses higher resolution and DNA microarrays</p> Signup and view all the answers

    What is considered a limit of using CGH in clinical settings?

    <p>It should not be used when knowledge of genetic status will not affect treatment decisions</p> Signup and view all the answers

    What advantage does Array CGH have over traditional CGH?

    <p>Greater resolution for smaller CNVs</p> Signup and view all the answers

    Why is Array CGH considered the gold standard for detecting CNVs?

    <p>It allows for high-resolution evaluations</p> Signup and view all the answers

    In what context is the use of CGH considered experimental?

    <p>Without symptoms or knowledge impacting treatment decisions</p> Signup and view all the answers

    What type of technology does Array CGH employ?

    <p>DNA microarrays targeting specific genome regions</p> Signup and view all the answers

    What is a common application of Array CGH outside of cancer research?

    <p>Prenatal genetic mutation screening</p> Signup and view all the answers

    What is one limitation of traditional Comparative Genomic Hybridization (CGH)?

    <p>It cannot detect small copy number variations (CNVs).</p> Signup and view all the answers

    What advantage does automated Comparative Genomic Hybridization (aCGH) have over traditional CGH?

    <p>It reduces human error and speeds up sample processing.</p> Signup and view all the answers

    Which type of chromosomal rearrangement cannot be detected by CGI?

    <p>Balanced rearrangements like translocations</p> Signup and view all the answers

    What does the spectral karyotyping (SKY) technique primarily allow for?

    <p>Visualization of chromosome pairs in different colors.</p> Signup and view all the answers

    What is a significant technical requirement for performing Comparative Genomic Hybridization (CGH)?

    <p>Specialized equipment and expertise.</p> Signup and view all the answers

    What aspect of the aCGH technique simplifies the process as compared to traditional hybridization methods?

    <p>No denaturation is required.</p> Signup and view all the answers

    Which of the following is a feature of aCGH in relation to traditional CGH?

    <p>Offers higher resolution for smaller CNVs.</p> Signup and view all the answers

    Why are balanced chromosomal rearrangements undetectable by CGH?

    <p>They do not change the copy number of DNA segments.</p> Signup and view all the answers

    Study Notes

    Cytogenetics Techniques

    • Karyotyping: Examines chromosomes in cells to identify genetic problems causing disorders or diseases.
    • Process: Culture cells, arrest at metaphase, prepare slides, stain, and visualize chromosome arrangements.
    • Chromosomal Banding Techniques: Several methods used to visualize banding patterns on chromosomes:
      • G-banding
      • R-banding
      • Q-banding
      • T-banding
      • Silver staining

    Molecular Cytogenetic Techniques

    • Fluorescence In Situ Hybridization (FISH): Molecular cytogenetic technique tagging genetic material with fluorescent molecules to map gene locations on chromosomes to detect small deletions and duplications.
    • Process: Denature DNA, label DNA probe, combine probe with target DNA, and visualize target sequence under a fluorescence microscope.
    • FISH Probe Types:
      • Whole chromosome
      • Unique sequence
      • Repetitive sequence
    • FISH Sample Types: Frozen sections, paraffin-embedded sections, cells in suspension (blood, bone marrow, amniotic fluid, etc.)

    Comparative Genomic Hybridization (CGH)

    • Method: Analyzes DNA copy number variations by comparing test DNA with a control DNA by hybridization on chromosome spreads followed by image analysis.
    • Applications: Identify gains or losses in DNA content, e.g., in cancer.

    Spectral Karyotyping (SKY)

    • Technique: Visualizes all chromosome pairs in different colors enabling the identification of chromosomal abnormalities.
    • Process: Uses fluorescent probes that label each chromosome, enabling visualization of the entire set under fluorescence microscopy.
    • Applications: Detect chromosomal abnormalities including translocations, deletions, and inversions.

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    UNIT 6 and 7 Molecular Cytogenetics Techniques PDF

    Description

    Explore various cytogenetic techniques including karyotyping and molecular cytogenetics. This quiz covers cellular processes, chromosomal banding techniques, and fluorescence in situ hybridization (FISH). Test your understanding of these methods used to identify genetic disorders and their underlying mechanisms.

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