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