Forensic Science

Blood What is made of? SUBSTANCE HOW DO WE KNOW IT’S BLOOD? Human?? Animal?? What does it do when it “travels”? BLOOD SPATTER

What makes up our blood? RED BLOOD CELLS (Erythrocytes) – –MOST ABUNDANT…contain HEMOGLOBIN –Do NOT have a nucleus – so they don’t have _______?? WHITE BLOOD CELLS (Leukocytes) – –IMMUNE CELLS PLASMA – –YELLOWISH LIQUID - nutrients and vitamins, hormones, clotting factors, and antibodies. PLATELETS (Thrombocytes) – –coagulate (clot) your blood, when you have a wound

What are blood types? UNIVERSAL DONORS: O type Rh – UNIVERSAL RECIPIENTS: AB type Rh +

How common is your blood type? 46.1% 38.8% 11.1% 3.9%

How do we know it’s blood? And if it’s blood, is it HUMAN? Is it blood? Kastle-Meyer test Uses Phenolthalein Detects Hemoglobin Turns pink if +

KASTLE-MEYER video clip

How do we know it’s blood? Is it blood (big area)? Luminol Drawbacks !! Some metals, paints, cleaning products, and plant materials also react. Can destroy DNA in blood.

Luminol can destroy evidence (DNA)

Crime Scene Analysis: Luminol in action

And if it’s blood, is it HUMAN? Is it HUMAN blood? Precipitin test 1. Inject rabbits w/ human blood 2. They will make ANTIBODIES to it 3. Extract antibodies from rabbit 4. Combine antibodies w/ crime sample 5. A precipitate line appears in tube if +

And if it’s blood, is it HUMAN? PRECIPITIN TEST Draw a test tube

And if it’s blood, is it HUMAN? PRECIPITIN TEST Draw a test tube. Like this one…

Is it HUMAN?? Microscope Views (visual examination) Bird Blood Cat Blood Dog Blood Fish Blood Frog Blood Snake Blood Human Blood Horse Blood