Forensic Science Unit 3: Blood & DNA
A person with B+ blood contains which antigen(s) on the surface of its red blood cells?
B and Rh
Blood Spatter
Can be analyzed to determine patterns that help determine how crime might have happened
If someone were to be shot by a handgun, the resulting blood spatter would be that of a ___________ velocity spatter
High
In gel electrophoresis, smaller molecules move _______ than larger molecules
Longer
If someone were to be hit once over the head by a hammer, the resulting blood spatter would be that of a ___________ velocity spatter
Low
If someone were to be beaten by a baseball bat, the resulting blood spatter would be that of a ___________ velocity spatter
Medium
In gel electrophoresis, DNA moves from the _______________ end to the _________________ end
Negative, positive
Blood type ______ is considered the universal donor
O-
RFLP
Process by which restriction enzymes are used to cut DNA into various lengths; requires large amounts of DNA and can take up to weeks to analyze
Luminol test
Solution sprayed where blood is suspected and if "positive" blue glowing light is produced - Same chemical used in "glowsticks"
If a person with B type blood is given A type blood, then
The donor's B antibodies will bind and to the recipient's B antigens, causing the blood to clump
PCR
a method used to rapidly make multiple copies of a specific segment of DNA; can be used to make millions of copies of DNA from a very small amount of DNA
Kastle-Meyer color test
a mixture of phenolphthalein and hydrogen peroxide; the hemoglobin will cause the formation of a deep pink color if blood is present
How should blood-containing clothes from a victim be packaged?
after it has dried, it should be packaging into a paper bag to prevent mold/bacteria growth
Passive spatter pattern
are created by the force of gravity acting on blood alone
transfer spatter pattern
are created when a wet, bloody surface comes in contact with a secondary surface
projected spatter pattern
are created when an exposed blood source is subjected to an action or force greater than the force of gravity
Blood antibodies
are proteins found in blood plasma that attach to antigens on the surface of red blood cells
How can you determine the area of convergence?
by drawing lines from the rounded edge of blood droplets, through it's tails, and noting where the two droplets intersect
blood spatter direction
can be determined by analyzing the direction that the blood droplet's tail is pointing towards
As the angle of impact decreases, the resulting blood droplet appears...
more elongated and elliptical
Hematest® tablet
reacts with the heme(iron) group in blood, creates a blue-green color
Angle of Impact
the angle at which a blood droplet strikes a surface
area of convergence
the location at which all blood spatters meet
Blood typing is based on
the presence or absence of certain antigens on the surface of the RBC
How should blood stains from a wall be collected?
using a sterile damp cotton swab which is then placed in a swab box (after drying)
If the first well contains DNA collected from a crime scene and all the other wells contain suspects' DNA, which well contains the culprit's DNA?
3
A person with A- blood contains which antigen(s) on the surface of its red blood cells?
A
Gel Electrophoresis
A procedure used to separate DNA fragments by size by placing a mixture of DNA fragments at one end of a porous gel and applying an electrical voltage to the gel
If someone has a positive blood type, then their red blood cells have ________ antigens on their surface
Rh