Explain in a new entry about the nature of blood, what makes up blood, how and what are blood characteristics. Document how blood is typed and what typing of blood shows us which has a direct affect on Forensic Science.
What questions MUST a criminalist answer when examining dried blood samples?
Explain Blood color testing and Blood origin testing. How does the criminalist individualize bloodstains?
what makes up blood:
Blood is typed as type A, B, AB, and O (but there are more breakdowns, positive and negative and the rhesus factor). On type A blood, there is an A antigen, on type B a b antigen, AB has neither the a and b antigen, and type O has both a and b antigen. DNA is vital evidence in resolving violent crimes and sex offenses. DNA is impartial, incriminating the guilty and exonerating the innocent.
when dealing with dried blood, the criminalist must answer the following questions:
1) Is it blood?
2) From what species did the dried blood originate?
3) If the blood is human, how closely can it be matched with a particular individual?
Blood color testing was commonly known as the benzidine color testing. but since benzidine is a carcinogen, it obviously is discontinued. Phenolphthalein has been substituted (kastle-meyer color test).
both tests are based on the observation that hemoglobin possesses peroxidase like activity. Peroxidase are enzymes that accelerate the oxidation of several classes of organic compounds when combined with peroxides.
once the stain has been characterized as bllod, the serologist determines whether the blood is of human or animal origin. the standard test for this is called the precipitin test. precipitin tests are based on the fact that when animals(usually rabbits) are injected with human blood, antibodies form that react with the invading human blood to neutralize its presence. the investigator can recover these antibodies by bleeding the animal and isolating the blood serum which contains antibodies that specifically react with human antigens.
when dealing with dried blood, the criminalist must answer the following questions:
1) Is it blood?
2) From what species did the dried blood originate?
3) If the blood is human, how closely can it be matched with a particular individual?
Blood color testing was commonly known as the benzidine color testing. but since benzidine is a carcinogen, it obviously is discontinued. Phenolphthalein has been substituted (kastle-meyer color test).
both tests are based on the observation that hemoglobin possesses peroxidase like activity. Peroxidase are enzymes that accelerate the oxidation of several classes of organic compounds when combined with peroxides.
once the stain has been characterized as bllod, the serologist determines whether the blood is of human or animal origin. the standard test for this is called the precipitin test. precipitin tests are based on the fact that when animals(usually rabbits) are injected with human blood, antibodies form that react with the invading human blood to neutralize its presence. the investigator can recover these antibodies by bleeding the animal and isolating the blood serum which contains antibodies that specifically react with human antigens.
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