Essay on Science: Blood and Trace Evidence

Submitted By Kperkins908
Words: 8264
Pages: 34

Simulated Blood Typing: Whodunit
Karl Landsteiner’s work made it possible to determine blood groups. In 1901 Landsteiner discovered human blood groups, from that blood transfusions became safer. Plasma, Red blood cells, White blood cells, and Platelets are the four components of blood. Blood is made of plasma, which is about ninety percent water. Plasma supply as the main transportation component in the body since it is the liquid part of blood. Red blood cells have a “lifespan” of about 120 days. The function of red blood cells is to transport oxygen throughout the body. Red blood cells have a protein call hemoglobin on their outer surface. Hemoglobin has iron molecules attached to it, and therefore has a strong affection for oxygen. The iron combining with the oxygen gives red blood cells their red color. White blood cells fight disease. White blood cells use chemicals that they produce and pick up on chemical signals from helper cells to identify and destroy objects. White blood cells destroy objects using variety of methods, including “eating” them, by attaching to the surface of the object so that the object can not bind with other cells. A huge increase or decrease in the number of white blood cells could mean that person is sick. An increased WBC count could mean an infection or leukemia, were as a low WBC count could mean HIV, some cancers, other diseases which have took over the immune system. Platelets, along with other proteins, form blood clots. When blood is exposed to air, platelets become sticky and for internal and external “scabs” to catch the blood cells and plasma, upon stopping bleeding. Human blood is grouped into four types: A, B, AB ,and O. Each letter refers to a kind of antigen on the surface of the red blood cells. Each blood type is also grouped by Rhesus Factor (Rh Factor). Blood is either Rh positive (Rh +) or Rh negative ( Rh -) and about 85 % of Americans have ( Rh+). Rhesus comes from Rhesus monkeys, which protein was discovered. Blood types become very important when a blood transfusion is necessary. In a blood transfusion a patient must receive a blood type that is compatible with their blood type, that is, the donated blood must be accepted by the patients own blood. If the blood types are not compatible, red blood cells will clump together, making clots that can block blood vessels and can cause death. Type O blood is considered the “universal donor” because it can be donated to people of any blood type. Type AB+ is considered the “universal recipient” because people with this type can receive an blood type. Agglutination occurs when different types of blood is mixed within the body. Sometimes when the blood types of two people are mixed, it clumps or forms visible islands in the liquid plasma, the red blood cells become attached to each other. The objective of this lab is to see which suspects blood type match to burglar’s blood type found at the crime scene.
Safety Precautions:
The team had to dress up with gloves, apron, and hair had to be tied back. Dealing with blood have many risks. “Dressing up” prevents the spread of blood-borne pathogens.
Carefully reading each label and dropping the antiserum in the correct place took time. After watching the agglutination process in each blood type the team had a hint of “whodunit.” See attached table to look at the comparisons and differences of each blood type.

The team looked at the table and saw that suspect 3 match the blood type that was found at the crime scene. If the burglar tries to deny his blood type, the team will explain to him that O blood is an “universal donor” and it can be donated to people of any blood type. So receiving a blood transfusion from type O blood doesn’t matter. The team decided to type the victim’s blood so they can determine whether the blood found at the scene is the victim’s or a suspect. Also to see if the victim may or may not need surgery from the…