Serology

• Blood components that are direct important aspects of blood identification:

  • Antigens
  • Antibodies
  • Red Blood Cells
• Antigens and antibodies found in each type of blood:

  • Type A blood: Antigen A, Antibody B
  • Type B blood: Antigen B, Antibody A
  • Type AB blood: Antigen A and B, No antibodies
  • Type O blood: No antigens or antibodies
• Occurrence rates of the various blood types:

  • Type O+: 38.4%
  • Type 0-: 7.7%
  • Type A+: 32.3%
  • Type A-: 6.5%
  • Type B+: 9.4%
  • Type B-: 1.7%
  • Type AB+: 3.2%
  • Type AB-: 0.7%
• How an investigator determines whether a bloodstain is of human or animal origin:

  • By testing for the presence of specific proteins or DNA markers that are unique to humans
  • Precipitin test
• How the type of surface affects the amount of blood spatter:

  • Porous surfaces absorb more blood, resulting in less spatter
  • Non-porous surfaces cause blood to pool and create more spatter
• “Genotype” and “phenotype” and which phenotypes can the genotypes of the individuals be directly known?:

  • Genotype: Genetic makeup of an individual
  • Phenotype: Observable characteristics
  • Phenotypes directly known from genotypes: ABO blood group
• Where antibodies are found:

  • Antibodies are found in plasma
• Antigen D is also known as:

  • Rh factor
• Karl Landsteiner:

  • Austrian biologist and physician who discovered the ABO blood group system
• Serum:

  • The liquid component of blood that remains after clotting
• What is a Gene and Chromosome:

  
  

  Gene: Unit of heredity that is passed from parent to offspring.

  Chromosome: Structure in cells that contains genes
• Blood spatter terms:

  • Parent drops: Main droplets of blood (droplet from which a satellite spatter originates)
  • Satellite spatter: Small droplets around the parent drop (small drops of blood that breaks off form the parent spatter when the blood droplet hits a surface)
  • Spines: Pointed edges of a bloodstain indicating direction of travel (pointed edges of a stain that radiates out the spatter; can help determine the direction from which the blood traveled)