BIO208 s09 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. What is the role of the centromere in cell division? 4. Scroll down the page and examine chromosomes 1, 4, and 14. The gray horizontal line indicates location of centromere. Sketch the p arm length relationship to the q arm in a metacentric, submetacentric, and acrocentric chromosome. Label p and q arms. Metacentric Submetacentric AcrocentricBIO208 s09 2 Return and select Make a Karyotype. Use the 3 features you indicated above to match each chromosome to its pair. 5. Is this a male or a female? 6. What is the chromosomal notation used to represent this person? 7. Fill in with either metacentric, submetacentric, or acrocentric Chromosome 2 Chromosome 4 Chromosome 11 Return and select Using Karyotypes to Predict Genetic Disorders. Play the normal fertilization movie. Use the forward button to move through animation. 8. How many chromosomes are contained in a human egg? human sperm? 9. How many copies of each chromosome are contained in a human zygote (fertilized egg)? Play the Trisomy movie 10. How many chromosomes does a person with a trisomy contain in each body cell? Scroll down and view the deletion animation. 11. What is the difference between an interstitial and a terminal deletion? 12. What is the difference between a Robertsonian and a reciprocal translocation? 13. Return to the main page and select Genetic Disorders Library. Read about of the disorders below and fill in the table. Disorder Chromosomal notation Incidence in population Sex (M,F, or either) 2 clinical features Turner Syndrome Down Syndrome Klinefelter Syndrome Cri du Chat Syndrome 46, 5p-BIO208 s09 3 14. What is non-disjunction (describe)? 15. Which one of the above genetic disorders is a monosomy? 16. Which one of the above genetic disorders is an autosomal trisomy? 17. Which one of the above genetic disorders involve a chromosomal deletion? 18. What is the sex of an individual of genetic makeup 48, XXXY? II. University of Wisconsin Waisman Center http://www.slh.wisc.edu/cytogenetics/ 1. What is cytogenetics? 2. Select Tests and sample requirements. List three body tissues or fluids used to obtain material to produce a karyotype. 3. Select Case Conference. Locate case August 1996. What is the patient background? 4. What is abnormal about the karyotype? 5. How many total chromosomes are present? 6. What is the cytogenetic designation for this disorder? 7. Was the fetus diploid, triploid, trisomic, or monosomic (choose one)? 8. Examine case October, 1996. The patient is a 29 year old woman that is mentally retarded and lacks hearing and speech. What is ectrodactyly? 9. View the Karyotype. a. What type of chromosomal abnormality is involved (translocation, deletion, duplication, inversion, trisomy) b. Which chromosome is affected? 10. Scroll down the page and Click on the schematic. a. Is this chromosome metacentric, submetacentric, or acrocentric? b. Which chromosomal arm is involved in this abnormality.BIO208 s09 4 11. Examine case November 1996. Read the patient background. a. What does CML stand for? b. What type of blood cell is involved? 12. What is the nomenclature this for chromosomal abnormality? 13. Which 3 chromosomes are involved in the translocation? 14. Click on the partial karyotype with schematic diagram. Examine the Philadelphia chromosome. Which 2 chromosomes composed the Philadelphia chromosome? 15. The Philadelphia chromosome that results from the translocation is the smallest one. Sketch the Philadelphia chromosome and identify ONLY the following: The Philadelphia chromosome 1. the TWO chromosomes involved 2. the centromere 3. the p and q arms. 16. Is the Philadelphia chromosome a metacentric, submetacentric, or acrocentric chromosome? 17. Are the translocations reciprocal or Robertsonian? 18. Is the presence of the Philadelphia chromosome diagnostic for CML? 19. 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 cancer.BIO208 s09 5 Abnormality Abbreviations: , Separates chromosome numbers, sex chromosomes, and chromosome abnormalities del Deletion der Derivative chromosome (used when one chromosome from a translocation is present) dic Dicentric dup Duplication fra Fragile site (usually used with Fragile-X syndrome) ins Insertion inv Inversion mar Marker chromosome (unidentifiable piece of chromosome) mat Maternally derived - Loss of a chromosome p Short arm of a chromosome ( ) Surround structurally altered chromosomes and breakpoints pat Paternally derived + Gain of a chromosome psu Pseudo- (precedes "dic" meaning pseudo dicentric) q Long arm of a chromosome ; Separates altered chromosomes and breakpoints involving more than one chromosome t Translocation ter Terminal end of arm (ie. 2qter - end of the long arm of chromosome 2) tri Trisomy trp Triplication General Guidelines: modal number, sex chrom, abn abbrev (first chrom; second chrom) (arm band number; arm band number) Ex: 46,XX,t(1;2)(p32;q22) Definitions: Modal number: total count of number of chromosomes in each cell of a given cell line Sex chromosomes: complement of X and Y chromosomes Band number: numerical description of the location on a chromosome arm, in order from the centromere out to the end of the chromosome. These numbers are a standard determined by the International System for human Cytogenetic Nomenclature (ISCN),