1. Unit 3: Blood Types/DNA/Spatter

2. Serology Serology is the examination and analysis of body fluids.
Chapter 10
Serology
Serology is the examination and analysis of body fluids.
A forensic serologist may analyze a variety of body fluids including saliva, semen, urine, and blood.
With the development of DNA techniques, more time, money, and significance were placed on developing DNA labs.
-However, with limited funds and the time required for DNA testing, most labs still use many of the basic serology testing procedures.
Kendall/HUnt

3. Blood Characteristics
Chapter 10
Blood Characteristics
Plasma is the fluid portion of the blood (55%)
Cells (45%)
Erythrocytes are red blood cells. They are responsible for oxygen distribution.
Leukocytes are the white blood cells; they are responsible for “cleaning” the system of foreign invaders.
Thrombocytes are platelets responsible for blood clotting.
Serum is the liquid that separates from the blood when a clot is formed.
Kendall/HUnt

4. Human versus Animal Blood
Chapter 10
Human versus Animal Blood
Animal Blood
Human Blood
Red blood cells are most numerous; 5 to 6 million per mm3
White blood cells are larger and less numerous; 5,000 to 10,000 per mm3
Platelets are tiny, cellular fragments; 350,000 to 500,000 per mm3
Larger nucleic red blood cells
Frog blood
Kendall/HUnt

5. Blood Types

6. Blood Typing Terminology
Chapter 10
Blood Typing Terminology
ABO blood groups—based on having A, B, both, or no antigens on red blood cells
Rh factor—may be present on red blood cells; positive if present and negative if not
Antigen—a substance that can stimulate the body to make antibodies. Certain antigens (proteins) found in the plasma of the red blood cell’s membrane account for blood type.
Antibody—a substance that reacts with an antigen
Agglutination—clumping of red blood cells; will result if blood types with different antigens are mixed
Kendall/HUnt

7. Chapter 10
Blood Typing
Blood type A has antigen A on the surface of the cell and will agglutinate with blood type B.
Blood type B has antigen B on the surface of the cell and will agglutinate with blood type A.
Blood type AB has antigens A and B on the surface of the cells
will not agglutinate if type AB receives any other type
Will agglutinate if donated to any other type
Blood type O has neither antigen A nor B
will not agglutinate if donated to any type
Will agglutinate if type O receives any other type
Kendall/HUnt

8. Agglutination Blood Clotting due to mixing of blood types
Why you must be careful when receiving blood
The picture on the left shows blood agglutination.
-Would happen if Type A mixes with Type B
-Would happen if any other type is donated to O
-Would happen if AB donates to any other types
The picture on the right shows no signs of agglutination
-Would happen if A mixes with A
-Would happen if B mixes with B
-Would happen if O is donated to anything
-Would happen if AB receives anything

9. Blood Types and Donation
Chapter 10
Blood Types and Donation
Can Give
Blood To
Type
Antigen
Antibody
Can Get
Blood From A A B
A, AB
O, A B B A
B, AB
O, B
Neither
A nor B AB
A and B AB
A, B, O, AB
Neither
A nor B O
A and B
A, B, O, AB O
Kendall/HUnt

10. Population Distribution of Blood Types in the U.S.
Chapter 10
Population Distribution of Blood Types in the U.S.
Type
Percent O 45 A 40 B 11 AB 4
Kendall/HUnt

11. Rh Factor -Another antigen that can be present + CANNOT donate to –
– CAN donate to +

12. Putting it All Together
O- is the universal donor
AB+ is the universal acceptor

13. Genotypes for blood type
ALLELE
CODES FOR IA
Type A Blood IB
Type B Blood i
Type O Blood
Type O is the recessive blood type, which is why it gets a lowercase (i).

14. Genotypes & Phenotypes of Blood
IAIA
Type A - Homozygous
IAi
Type A - Heterozygous
IAIB
Type AB - Heterozygous
IBIB
Type B - Homozygous
IBi
Type B - Heterozygous ii
Type O – Homozygous recessive

15. Example Problem: IB i IAIB IAi IA
Dad is homozygous for Type A blood. Mom is heterozygous for Type B blood. Do a Punnett Square to find out the offspring.
IB i
IAIB
IAi
Child Genotypes and Phenotypes
IAIB Type AB (50%)
IAi Type A (50%) IA

16. DNA Analysis

17. General DNA Information
Double helix—two coiled DNA strands
In humans, the order of these bases is 99.9% the same.
Four bases
Adenine
Cytosine
Guanine
Thymine

18. DNA Base Pair Matching Bases always pair A to T and G to C
Original DNA Strand: AATCAGTCG
Complimentary Strand: TTAGTCAGC
You Try it!
Original: TCCGATTCAAG
Complimentary Strand: __________________

19. Types of DNA Nuclear Mitochondrial In all nucleated cells
Inherited 50% from each parent
Mitochondrial
In all cells
Inherited ONLY FROM MOTHER

20. Where Is DNA Found? Nuclear DNA is found in all nucleated body cells—
white blood cells
Semen
Saliva
Urine
hair root
Teeth
Bone
Tissue
Cheek cells are the most common site for DNA sampling
Red blood cells have no nuclei = no nuclear DNA
DNA obtained from blood comes from white blood cells

21. DNA Typing
DNA typing is a method in which DNA is converted into a series of bands that ultimately distinguish each individual.
Only .1% of DNA differs from one person to the next.
-Scientists use these regions to generate a DNA profile of an individual.

22. Uses of DNA Profiling To identify potential suspects
To exonerate individuals
To identify crime and casualty victims
To establish paternity
To match organ donors

23. DNA TYPING “Fingerprinting”
PCR—Polymerase Chain Reaction

24. PCR—Polymerase Chain Reaction
PCR is a technique used for making copies of a defined segment of a DNA molecule.
This can be valuable when the amount of evidence is minimal.
Millions of copies of DNA can be made from a single speck of blood.

25. Intro to Gel Electrophoresis

26. Electrophoresis A technique used to separate DNA fragments.
An electrical current is moved through a gel substance causing molecules to sort by size.
The smaller, lighter molecules will move the furthest on the gel.

27. Electrophoresis Step 1: Pipette the DNA.
Step 2: Load DNA into the gel wells.
Step 3: Run the gel.
Step 4: Observe and compare bands of DNA.

28. Three Possible Outcomes
Match—The DNA profile appears the same. Lab will determine the frequency.
Exclusion—The comparison shows profile differences that can only be explained by the two samples originating from different sources.
Inconclusive—The data does not support a conclusion as to whether the profiles match.

29. Reading Results Practice

30. Who Should be arrested?

31. FBI’s CODIS DNA Database
Combined DNA Index System
Used for linking serial crimes and unsolved cases with repeat offenders
Launched October 1998
Links all 50 states

32. Blood Spatter Analysis

33. Blood Spatter Evidence
Chapter 10
Blood Spatter Evidence
A field of forensic investigation that deals with:
Physical properties of blood
Patterns produced under different conditions as a result of various forces being applied to the blood.
Considered circumstantial and class evidence
Blood, as a fluid, follows the laws of physics.
Kendall/HUnt

34. Blood Droplet Characteristics
Chapter 10
Blood Droplet Characteristics
A blood droplet remains spherical in space until it collides with a surface.
Once a blood droplet impacts a surface, a bloodstain is formed.
Droplets falling from the same height, hitting the same surface at the same angle, will produce stains with the same basic shape.
Kendall/HUnt

35. Questions Answered by Blood Spatter Interpretation
Chapter 10
Questions Answered by Blood Spatter Interpretation
The distance between the target surface and the origin of the blood
The point(s) of origin of the blood
Movement and direction of a person or an object
The number of blows causing the bloodshed
Type and direction of impact
The position of the victim and/or object during bloodshed
Movement of the victim and/or object after bloodshed
Kendall/HUnt

36. Conditions Affecting Shape of Blood Droplet
Chapter 10
Conditions Affecting Shape of Blood Droplet
Direction
Angle of impact
Velocity at which the blood droplet left its origin
Height from where blood dropped
Kendall/HUnt

37. Blood Stain Patterns-Velocity
Chapter 10
Blood Stain Patterns-Velocity
Kendall/HUnt

38. Bloodstain Patterns-Direction
Chapter 10
Bloodstain Patterns-Direction
The pointed end of the bloodstain faces the direction of travel.
If there is more than one drop, you can determine point of origin (where direction lines intersect)
Kendall/HUnt

39. Bloodstain Patterns-Height
Chapter 10
Bloodstain Patterns-Height
Higher drop point = larger spatter
Diameter increases
Kendall/HUnt

40. Bloodstain Patterns-Angle of Impact
Chapter 10
Bloodstain Patterns-Angle of Impact
The shape of a blood drop:
Round—if it falls straight down at a 90-degree angle
Elliptical—blood droplets elongate as the angle decreases from 90 to 0 degrees; the angle can be determined by the following formula:
Kendall/HUnt

41. Bloodstain Patterns-Angle of Impact
Chapter 10
Bloodstain Patterns-Angle of Impact
The more acute the angle of impact, the more elongated the stain.
90-degree angles are perfectly round drops
80-degree angles take on a more elliptical shape.
At about 30 degrees the stain will begin to produce a tail.
Kendall/HUnt

42. Bloodstain Patterns-Angle of Impact PRACTICE
Chapter 10
Bloodstain Patterns-Angle of Impact PRACTICE
1) Measure width and length
2) Divide the length by the width
3) take the sin-1 of that number
Try with the above blood drops to see if your work matches the actual angle of impact
Kendall/HUnt