Monday, February 25, 2019

Blood Typing Lab

Name_____________________________________ Block__________________ Date_____________________ Forensics Mystery Blood Typing Lab Scenario practice of law are called to a ho exercise where they discover a body full the back door. There is a fresh pool of rent by the victims head. Officers question the neighbors and learn that a plumber and an lineman made service calls to the house just hours before. They were able to trace both(prenominal). They incur a shirt with a dark stains from the service a vanguardt-garde of the plumber and rags with similar dark stains from electricians van.Your forensics lab brings the following items to campaign take 1 Stained cloth from plumbers van prototype 2 Stained cloth from the electricians van Sample 3 Blood collected from under the victims head study Background The phenolphthalein test is a highly sensitive, beingness capable of detecting fall spots practically invisible to the eye. In an actual criminal case, a positive phenolphthalein test would be followed by tests to determine the species that produced the rail line and if these tests indicate the blood is human, by tests to determine ABO, Rh and other blood groups.There is no point in pursuing type and species identification procedures if the phenolphthalein test is negative. The phenolphthalein test is not absolutely specific for blood because most plants and some animal cells can also cause a positive reaction. Discussion Questions 1. Does a positive phenolphthalein test confirm that a stain is caused by blood? 2. Does a positive phenolphthalein test prove that a stain is caused by human blood? Procedure 1 1. Test the shirt and rags to determine if the stains are caused by blood. 2. Place a drop of phenolphthalein/peroxide solution on individually stain. 3.Observe if a food coloring change occurs. A purple-violet color reaction indicates that blood (heme) is symbolise (positive reaction). absence of this reaction indicates that blood is not present. 4. Record your results Color reaction for Sample 1_________________________ Color reaction for Sample 2_________________________ base on the results of this test, which soulfulness, the plumber or the electrician be flummoxs your prime suspect? ____________________________________________________________________________ Additional development When confronted, your chief suspect claims to obligate a nosebleed, thus accounting for the blood stain.Investigators have now been able to recover a blood audition (Sample 4 ) from the suspects van. It is suitable for blood typing. You ask and receive a blood sample from the suspect (Sample 5). Proceed to Procedure 2. Test Background Blood groups are created by molecules present on the draw near of red blood cells. The table shows the four ABO phenotypes (blood groups) present in the human population. When red blood cells carrying one or both antigens are exposed to the corresponding antibodies, they agglutinate that is, clump together.P eople usually have antibodies against those red cell antigens that they lack. The ABO Blood Groups Blood Group rose-cheeked Cell Antigen (Protein on blood cell) Serum Antibody (Produced by Body) A A Anti-B B B Anti-A AB A and B Neither O Neither Anti -A and Anti -B Discussion Questions 1. How do you determine a persons blood type? 2. Can a persons blood type prove or disprove that he/she committed a crime? How? Procedure 2 1. Add a drop of synthetic anti-A (blue) to the hygienic labeled A. Replace cap. . Always exchange the cap on the ampoule before opening the next vial to prevent cross contamination. . Add a drop of synthetic anti-B (yellow) to the well labeled B. Replace cap. 3. Add a drop of synthetic anti-Rh blood serum (clear) to the well labeled Rh. Replace cap. 4. Using the dropper vial, place a drop of Sample 3 (the victims blood) in each well of the blood typing slide. DO NOT TOUCH THE soundly 5. Replace the cap on the dropper vial. 6. Using a varied color mixing st ick for each well (blue for anti-A, yellow for anti-B & flannel for anti Rh), gently stir the synthetic blood and anti-serum drops for 30 seconds.Remember to shake off each mixing stick after a single use to avoid cross contamination. 7. WAIT 60 Seconds. 8. Carefully examine the make out films of liquid mixture left behind. If the film remains uniform in appearance, there is no agglultination (no clumps, negative reaction). If the film as clumps, agglutination has occurred (positive reaction) 9. lay out blood type of the sample using the data table below. firmness of purpose yes or no as to whether agglutination occurred in each sample. A positive agglutination reaction indicates blood type. 10. Record the results for each blood sample in the data table.Data Table Sample 3 Sample 4 Sample 5 Anti-A Anti-B Rh Blood type 11. whence repeat steps 1-9 for Samples 4 and 5. Record each results on table. 12. thoroughly rinse the blood typing slides and return all material s. Conclusion Based on your results, did the blood collected from the suspects van come from the suspect? ____________________________________________________ Could this blood have come from the victim? ____________________________ What can you cogitate from your results? (Remember to cite your data). __________________________________________________________________________________ ___________________________________________________________________________________ ___________________________________________________________________________________ ___________________________________________________________________________________ ___________________________________________________________________________________ ___________________________________________________________________________________ ___________________________________________________________________________________ ___________________________________________________________________________________ ______________________ ________________________________________________________________________________________________________________________________________________

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