There are 20 questions to answer. They are numbered 4-23. Read each slide. The questions (and answers) are straight off of the slides. You do not have to write the questions, just the answers.

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Blood cells are made inside the bone

marrow

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Plasma Over time, the solids in blood will settle to the bottom, leaving a clear fluid called Plasma

Serum • Characterized by its yellow hue,

and contains white blood cells and

platelets.

• Forensic analysts able to determine

the freshness of a blood sample by

examining serum (it clots several

minutes after exposure to air).

• A centrifuge can be used to

separate the clotted material from

the serum portion.

• Serum contains antibodies , proteins

floating in blood fluid, which have

significant forensic implications.

Blood Plasma contains carbohydrates, lipids, hormones, inorganic salts, proteins (such as antibodies), and clotting elements

4. Slides 1-8: Describe the parts of the blood and their functions on the back of your lab sheet.

5. Slides 8-11: Describe blood plasma or serum. Include the color.

Collection of evidence • Evidence must be collected and handled in a way that

prevents any change from taking place between the time

it is removed and the time it arrives at the lab.

Collecting tools

• The tools used in the

collection process are

as important as the

collection itself.

– Using the incorrect

tools can result in

contamination

Chain of Custody

• A written log of where evidence is and who

may have it, must be kept at all times.

• Any break in the chain will result in the

evidence being inadmissible in court

• Collection tools also

include the packaging

devices.

– In general manila

envelopes, pill bottles,

and cardboard pill

boxes are suitable

Collecting blood evidence

• When collecting blood evidence what type

of container should you use?

• If you use an airtight container then the

condensation is conducive to mold growth

and can ruin evidence.

6. What is Chain of Custody?

7. What is important to remember when collecting Blood Evidence?

The direction of travel of blood striking an object may be determined because the pointed end of a bloodstain always faces its direction of travel.

• From what direction did this blood come?

• The “tail” of a blood drop points to the direction it was moving!

8. Write this sentence:

The direction of the tail faces (the same/the opposite) as the direction of travel

SIN < = Width (a) 1.5cm

Length (c) 3.0cm

SIN < = 0.5

< = 30 degrees

9. What angle produces round drops?

Point of Origin – Draw lines through the long axis of each drop. Where the

lines converge is where the blood spatter originated – the Point of Origin.

10. How do you calculate the Point of Origin?

Can you complete this one?

Can you complete this one?

Point of

Origin

Point of Convergence (POC)

29

Blood or Unknown Stains at the

Crime Scene Whenever blood is found there are four

questions to ask:

1. Is it really blood?

2. Is the blood human?

3. From whom did the blood come?

4. How did the blood get there?

30

Is it really blood?

Luminol Test Luminol reagent is sprayed onto a surface,

in as dark of a room as possible.

If blood is present a luminescent glow will

show in the area of the blood, as it reacts

with the iron in the hemoglobin.

The Luminol test is very sensitive and can

detect bloodstains diluted up to 10,000

times!

Can be false positive with feces, urine, or

some bleaches

Luminol Test

Phenolphthalein( Kastle- Meyer’s) Test

33

Is it really blood?

Hemastix Strips Strip is moistened with distilled water and

placed on blood stain.

If blood is present, the strip will turn green.

34

Is the blood human?

To determine whether a blood sample is

from a human or animal source, samples

are tested with anti-human serum.

The forensic test consists of collecting the

blood sample in a test tube containing an

animal-derived serum containing antibodies

against human blood.

If an insoluble complex of precipitin (this

would be visible as agglutination) occurs, the

test is positive for human blood.

The precipitin test

Gel Diffusion

11. Hemostix test for what?

12. What does Luminol require to work?

13. Precipitin is also called Agglutination. Agglutination means something clumped up, or clotted. When the blood from the rabbit agglutinates, it proves that ___

From whom did the blood come?

Blood typing and/or DNA testing

(discussed later) can determine this.

History of Blood Groups and Blood Transfusions

•Experiments with blood transfusions have been carried out for hundreds of years. Many patients have died and it was not until 1901, when the Austrian Karl Landsteiner discovered human blood groups, that blood transfusions became safer. • He found that mixing blood from two individuals can lead to blood clumping. The clumped RBCs can crack and cause toxic reactions. This can be fatal.

http://nobelprize.org/medicine/educational/landsteiner/readmore.html

Early blood transfusions – approximately 50% mortality rate (1/2 the

people died)

Genetics of Blood Types

• Your blood type is established before you are BORN, by specific GENES inherited from your parents.

• You inherit one gene from your MOTHER and one from your FATHER.

• These genes determine your blood type by causing proteins called AGGLUTINOGENS to exist on the surface of all of your red blood cells.

According to the ABO blood typing system there are four different kinds of blood types: A, B, AB or O (null).

•The blood group you belong to depends on what you have inherited from your parents.

ABO blood grouping system

AUTOSOMAL CHROMOSOME

Mustafa

Sara

one allele from Mustafa and one from Sara – child will have type AB blood

The alleles for Blood group are in the same

place on the chromosome 9. Each person gets one allele from their mother, and one from their father

A B

• Antigens, usually

proteins, are located on the surface of

red blood cells and are responsible for blood-type characteristics.

14.The protein on the red blood cell is called an ____ and is responsible for the ____ _____ _____

What are blood types?

http://learn.genetics.utah.edu/units/basics/blood/types.cfm

There are 3 alleles or genes for blood

type: A, B, & O. Since we have 2 genes,

there are 6 possible combinations.

Blood Types

AA or AO = Type A

BB or BO = Type B

OO = Type O

AB = Type AB

Copyright © 2013 Crosscutting Concepts, LLC. All Rights Reserved.

www.CrosscuttingConcepts.com

Blood Types

• ABO blood group antigens present on red blood cells

• IgM antibodies present in the serum.

15.The ____ is found in the plasma and is responsible for the blood _____ when the wrong type is transfused.

Blood group A Blood group A=A Antigen On RBCs B antibodies in your blood plasma.

Blood group B Blood group B=B antigens RBCs A antibodies in your blood plasma.

AB0 blood grouping system

Blood group O Blood group O, neither A or B antigens on the surface of your RBCs Both A and B antibodies in your blood plasma.

16.What are the 4 blood types?

17.What are the 2 different blood alleles?

18.Which blood type has neither allele?

19.Which blood type has both alleles?

20.Every person gets ___ allele from their father and ____ allele from their mother.

Blood 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

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 and will not agglutinate with either type A or type B blood.

Blood type O has neither antigen A nor B and will not agglutinate.

Rh Factors

• Scientists sometimes study Rhesus monkeys to learn more about the human anatomy because there are certain similarities between the two species. While studying Rhesus monkeys, a certain blood protein was discovered. This protein is also present in the blood of some people. Other people, however, do not have the protein.

• The presence of the protein, or lack of it, is referred to as the Rh (for Rhesus) factor.

• If your blood does contain the protein, your blood is said to be Rh positive (Rh+). If your blood does not contain the protein, your blood is said to be Rh negative (Rh-).

A+ A-

B+ B-

AB+ AB-

O+ O-

http://www.fi.edu/biosci/blood/rh.html

How common is your blood type?

46.1%

38.8%

11.1%

3.9%

21.The most common blood type is type ___.

To Test for Blood Type:

Expose blood drop to

material that reacts with

A, and with B

If the blood reacts, it is

that type

Blood Groups

Type Antigen Will kill

type:

Can Give

Blood To Can Get

Blood From

A

B

AB

O

A

B

A and B

Neither

A nor B

B or O

A or O

A, B, or O

Safe for all

A, AB O, A

B, AB O, B

AB

A, B, O, AB

A, B, O, AB

O

22.Is this OK? A person with type AB blood receives type O blood in a transfusion?

23.Is this OK? A person with type O blood receives type B blood in a transfusion?