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Chapter 8 Forensic Serology Edited by: Alex Smith

Chapter 8 Forensic Serology Edited by: Alex Smith. Courtesy of C. Fanning. Plasma. Plasma, which is the fluid portion of blood, is composed principally of water. Red blood cells ( erythrocytes ), white blood cells ( leukocytes ), and platelets are the solid materials suspended in plasma.

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Chapter 8 Forensic Serology Edited by: Alex Smith

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  1. Chapter 8 Forensic Serology Edited by: Alex Smith Courtesy of C. Fanning

  2. Plasma • Plasma, which is the fluid portion of blood, is composed principally of water. • Red blood cells (erythrocytes), white blood cells (leukocytes), and platelets are the solid materials suspended in plasma.

  3. More than 15 blood antigen systems have been identified, but the A-B-O and Rh systems are the most important. • An individual that is type A has A antigens on his/her red blood cells, type B has B antigens, AB has both A and B antigens, and type O has neither A nor B antigens. • Rh factor is determined by the presence of another antigen, the D antigen. • People having the D antigen are Rh positive; those not having the antigen are Rh negative. • Antigens, usually proteins, are located on the surface of red blood cells and are responsible for blood-type characteristics • Cont. Antigens

  4. For every antigen there is a specific antibody that will react with it to form clumps known as agglutination. Thus, if serum containing anti-B is added to red blood cells carrying B antigen, they will immediately react. Agglutination

  5. The term serology is used to describe a broad scope of laboratory tests that use specific antigen and serum antibody reactions. • The identity of each of the four A-B-O blood groups can be established by testing the blood with anti-A and anti-B sera. Serology

  6. Alternatively, the luminol test is used to search out trace amounts of blood located at crime scenes. • Luminol produces light (luminescence) in a darkened area. Luminol Courtesy of C. Fanning Luminol with false positive (bleach) Courtesy of C. Fanning Courtesy of C. Fanning

  7. Precipitin • The precipitin test uses antisera normally derived from rabbits that have been injected with the blood of a known animal to determine the species origin of a questioned bloodstain. • Once it has been determined that the bloodstain is of human origin, an effort must be made to associate or dissociate the stain with a particular individual. • DNA analysis has allowed forensic scientists to associate blood to a single individual.

  8. Allele • Alternative forms of genes that influence a given characteristic (such as eye color or blood type) are known as alleles.

  9. Antibody • A protein that destroys or inactivates a specific antigen; antibodies are found in the blood serum

  10. Antiserum • Blood serum that contains specific antibodies

  11. Aspermia • The absence of sperm; sterility in males

  12. Chromosome • A rodlike structure in the cell nucleus, along which the genes are located; it is composed of DNA surrounded by other material, mainly proteins

  13. Deoxyribonucleic Acid (DNA) • Abbreviation for deoxyribonucleic acid—the molecules carrying the body’s genetic information; DNA is double stranded in the shape of a double helix

  14. Egg • The female reproductive cell

  15. Enzyme • A protein that acts as a catalyst for certain specific reactions

  16. Erythrocyte • A red blood cell

  17. Genotype • The particular combination of genes present in the cells of an individual

  18. Heterozygous • Having two different allelic genes on two corresponding positions of a pair of chromosomes

  19. Homozygous • Having two identical allelic genes on two corresponding positions of a pair of chromosomes

  20. Hybridoma cells • Fused spleen and tumor cells; used to produce identical monoclonal antibodies in a limitless supply

  21. Locus • The physical location of a gene on a chromosome

  22. Hemoglobin • A positive result from the Kastle-Meyer color test is highly indicative of blood. Hemoglobin causes a deep pink color.

  23. Monoclonal antibodies • A collection of identical antibodies that interact with a single antigen site

  24. Gene • The transmission of hereditary material is accomplished by means of microscopic units called genes, located on chromosomes.

  25. Acid Phosphatase • The best way to locate and at the same time characterize a seminal stain is to perform the acid phosphatase (an enzyme secreted into seminal fluid) color test. • A purple color indicates acid phosphatase enzyme.

  26. Oligospermia • An abnormally low sperm count

  27. Phenotype • The physical manifestation of a genetic trait such as shape, color, and blood type

  28. Polyclonal antibodies • Antibodies produced by injecting animals with a specific antigen; a series of antibodies are produced responding to a variety of different sites on the antigen

  29. Serum • The liquid that separates from the blood when a clot is formed

  30. Sperm • The male reproductive cell

  31. X Chromosome • The female sex chromosome

  32. Y Chromosome • The male sex chromosome

  33. Zygote • The cell arising from the union of an egg and a sperm cell

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