BIO208 2011 1 CYTOGENETICS A karyotype is a visual display of chromosomes arranged by size. A sample of blood is obtained and white blood cells (lymphocytes and monocytes) purified. The cells are cultured for 4 days with a growth stimulator (phytohemagglutinin) that increases cell proliferation. Cells are treated with a drug to arrest cell division (colchicine disrupts mitotic spindles) which enriches the proportion of metaphase chromosomes in the cell culture. The cells are exposed to water which makes them swell. A slide is prepared and stained and a photograph taken so that chromosome images can be arranged. I. University of Utah http://learn.genetics.utah.edu/ Select Heredity and Traits Select How Scientists Read Chromosomes Read the text and examine the figures 1. How does Giesma stain assist in identifying chromosomes? 2. List 2 other features used to distinguish chromosomes. 3. Examine the image of the dividing cell. What happens to the microtubules connected to the chromosomes’ centromeres as the cell proceeds through cell division? 4. Scroll down the page and examine chromosomes 1, 4, and 14. The gray horizontal line indicates location of centromere. a. Sketch the p arm length relationship to the q arm in a metacentric, submetacentric, and acrocentric chromosome. b. Label p and q arms. Metacentric Submetacentric Acrocentric c. What is the approximate ratio of the length of the p/q arms in a metacentric chromosome?BIO208 2011 2 5. Return and select Make a Karyotype. Use the 3 features you indicated above to match each chromosome to its pair. a. Is this a male or a female? How do you know? b. Fill in using one of the following terms: metacentric, submetacentric, or acrocentric Chromosome 1 _____________ Chromosome 10 _____________Chromosome 15 _____________ Return and select Using Karyotypes to Predict Genetic Disorders. 6. Play the fertilization movie. Use the forward button to move through animation. a. How many chromosomes are contained in a human egg? human sperm? b. How many copies of each chromosome are contained in a human zygote (fertilized egg)? 7. Play the trisomy movie. How many chromosomes does a person with a trisomy contain in each body cell? 8. Scroll down and view the deletion animation. What is the difference between an interstitial and a terminal deletion? 9. View the translocation movie. What is the difference between a Robertsonian and a reciprocal translocation? 10. Return to the main page and find Genetic Health and the Genetic Disorders Library (use right and left arrows at bottom of main page). Pick 2 of the following disorders which involve large pieces of, or whole chromosomes, and answer the questions for each. Turner syndrome/ Klinefelter syndrome/ Williams syndrome/ Down syndrome/ Cri du Chat syndrome A. Name of syndrome____________________________________ o Chromosome(s) involved o 5 clinical symptoms o How disorder is diagnosed in the newborn o Is the disorder a monosomy? A trisomy? A deletion? A translocation? (pick one) o These disorders often occur due to non-disjunction of chromosomes in meiosis. Is there evidence as to whether the abnormal meiosis occurs in the sperm, or in the egg? Explain.BIO208 2011 3 B. Name of syndrome______________________________________ o Chromosome(s) involved o 5 clinical symptoms o How disorder is diagnosed in the newborn o Is the disorder a monosomy? A trisomy? A deletion? A translocation? (pick one) o These disorders often occur due to non-disjunction of chromosomes in meiosis. Is there evidence as to whether the abnormal meiosis occurs in the sperm, or in the egg? Explain. II. University of Wisconsin Waisman Center http://www.slh.wisc.edu/cytogenetics/ 1. What is cytogenetics? 2. Select Tests and sample requirements. What are these body tissues commonly used for genetic analysis? Amniotic fluid Chorionic villi Bone marrow Tumor 3. Select Case Conference. Locate case August 1996. a. From where was the sample obtained? b. What is abnormal about the karyotype? c. How many total chromosomes are present? d. Scroll down to find the cytogenetic designation for this disorder and indicate here. e. Was the fetus diploid, triploid, trisomic, or monosomic (choose one)?BIO208 2011 4 4. Select case October, 1996. The patient is a 29 year old woman that is mentally retarded and lacks hearing and speech. a. What is ectrodactyly? b. What type of chromosomal abnormality is involved (translocation, deletion, duplication, inversion, trisomy) c. Which chromosome is affected? d. Scroll down the page and Click on the schematic. Which chromosomal arm is involved in this abnormality? 5. Select case November 1996. Read the patient background. a. What does CML stand for? b. What type of blood cell is involved? c. What is the nomenclature this for chromosomal abnormality? d. Which 3 chromosomes are involved in the translocation? e. Click on the partial karyotype with schematic diagram. The Philadelphia chromosome is the smallest one. Sketch the Philadelphia chromosome and identify the following: The Philadelphia chromosome 1. the TWO chromosomes involved 2. the centromere 3. the p and q arms. f. Is the presence of the Philadelphia chromosome diagnostic for CML? g. How can a translocation cause cancer if there is no loss or gain of genetic material? This can be researched at http://www.nature.com/scitable. Search with the terms Chromosomes