BIOT303 Lecture 9: Molecular Cytogenetics

Clinical cytogenetics is the study of the relationship of chromosomal alterations (including both structural and numerical) and genetic disease in humans using the conventional techniques.

Molecular cytogenetics is a study of genetic disorders associated with chromosomal abnormalities using new technologies that combine cytogenetic and molecular techniques.

The karyotyping procedure involves culturing blood cells, adding colchicine to stop mitosis at metaphase, spinning down the cells in a centrifuge, discarding the supernatant, adding hypotonic salt solution and resuspending the cells, adding fixative to the cell suspension, drying, and staining with Giemsa.

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

<p>An ideogram is a diagrammatic representation of the chromosomes, showing their relative size and chromosomal landmarks.</p> Signup and view all the answers

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

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

<p>Heterochromatin is a highly condensed, mostly highly repetitive DNA arranged in tandem arrays, very few genes.</p> Signup and view all the answers

<p>The three main molecular cytogenetic techniques are Fluorescence in situ Hybridization (FISH), Multiplex-FISH, Spectral Karyotyping (SKY), and Array-based Comparative genomic hybridization (aCGH).</p> Signup and view all the answers

<p>FISH maps DNA sequences to specific regions of human chromosomes. Fluorescently labeled DNA probes hybridize to complementary chromosomal regions, resulting in a fluorescent dot at the chromosomal location where the labeled probe binds. This technique allows higher resolution than standard G-banding approaches.</p> Signup and view all the answers

<p>Advantages of FISH include the ability to detect specific DNA sequences in the interphase or during the metaphase and results are available within 24-48 hrs. Disadvantages include the inability to detect big structural rearrangements, some abnormalities are undetectable and sometimes the procedure can destroy the test itself.</p> Signup and view all the answers

<p>Multiplex-FISH or spectral karyotyping is a laboratory technique that allows scientists to visualize all of the human chromosomes at one time by painting each pair of chromosomes in a different fluorescent colour.</p> Signup and view all the answers

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

<p>aCGH stands for Array-based Comparative Genomic Hybridization.</p> Signup and view all the answers

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

<p>The aCGH procedure involves labeling control DNA with green dye and patient DNA with red dye, applying this labeled DNA to a microarray, hybridizing the DNA, scanning fluorescent signals with a microarray scanner, analyzing data using computer software, and generating a plot.</p> Signup and view all the answers

<p>FISH primarily focuses on examining specific regions of chromosomes, while aCGH provides a genome-wide analysis of copy number variations, allowing for identification of gains or losses across the entire genome.</p> Signup and view all the answers

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

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

<p>A DNA probe in FISH is a short, single-stranded DNA sequence, labeled with a fluorescent dye, that hybridizes to complementary sequences in the target chromosomal DNA. This hybridization allows for visualization of specific regions of interest on the chromosomes.</p> Signup and view all the answers