Serology

Question 1

What is the purpose of forensic serology?

Answer 1

• To identify body fluids present that may be associated with a crime
• To determine source of the body fluid

Question 2

What is serology?

Answer 2

• Analysis and identification of body fluids present stains
• Blood, semen, and saliva
• Analysis of bloodstain patterns
• Cannot individualize body fluids to a particular person
• DNA is used to individualize source of stain

Question 3

Characteristics of body fluid stains

Answer 3

• May be in multiple locations
• Blood is a perishable biological material
• May be degraded or putrefied
• Failure to collect and preserve it properly may result in spoilage, inability to analyze it, or inadmissibility of results in court

Question 4

How is body fluids packaged? Short-term and long-term?

Answer 4

• Need to be air dried before packaged
• Short-term storage -> refrigerator
• Long-term -> freezer

Question 5

Type of tests to indicate body fluids?

Answer 5

Presumptive tests and confirmatory tests

Question 6

What are presumptive tests?

Answer 6

• Very sensitive for a substance, but not specific for the substance

Question 7

What are confirmatory tests?

Answer 7

• Specific for a particular substance
• “Confirms” the presence of a substance

Question 8

What is the liquid portion of the blood?

Answer 8

• 55% of blood volume
• Contains proteins, carbohydrates, fats, salts, minerals, and antibodies

Question 9

What is the solid portion of blood?

Answer 9

• Remaining 45% of blood
• made up of red blood cells, white blood cells, and platelets

Question 10

What is the liquid portion of clotted blood?

Answer 10

Serum

Question 11

What are characteristics of red blood cells (erythrocytes)?

Answer 11

• Formed in bone marrow
• Transport oxygen to cells
• Remove carbon dioxide from cells

Question 12

What are characteristics of white blood cells (leukocytes)?

Question 13

What is the purpose of forensic serology?

Answer 13

To identify body fluids present that may be associated with a crime and to determine the source of the body fluid.

Question 14

Define serology in the context of forensic science.

Answer 14

Analysis and identification of body fluid stains, including blood, semen, and saliva.

Question 15

What can forensic serology not accomplish regarding body fluids?

Answer 15

Cannot individualize body fluids to a particular person; DNA is used for individualization.

Question 16

What is the liquid portion of blood called?

Answer 16

Plasma.

Question 17

What percentage of blood volume is made up of plasma?

Answer 17

55%.

Question 18

What constitutes the solid portion of blood?

Answer 18

Red blood cells, white blood cells, and platelets.

Question 19

What are the three main types of cells in blood?

Answer 19

• Red blood cells (erythrocytes) * White blood cells (leukocytes) * Platelets (thrombocytes)

Question 20

What is the role of red blood cells?

Answer 20

Transport oxygen to cells and remove carbon dioxide from cells.

Question 21

What is the role of white blood cells?

Answer 21

Part of the immune system – fight infection.

Question 22

What is the major part of the clotting process?

Answer 22

Platelets (thrombocytes).

Question 23

What are the first questions to answer when examining dried blood?

Answer 23

• Is it blood? * From what species did the blood originate? * If human, how closely can it be associated to a particular individual?

Question 24

What is a presumptive test?

Answer 24

A very sensitive test for a substance, but not specific for that substance.

Question 25

What is a confirmatory test?

Answer 25

A test that is specific for a particular substance and 'confirms' its presence.

Question 26

What does the Kastle-Meyer test detect?

Answer 26

Presence of blood by changing color from colorless to pink.

Question 27

What is luminol used for in forensic serology?

Answer 27

To identify patterns of suspected blood that are not visible or may have been cleaned up.

Question 28

True or False: Luminol is the most sensitive presumptive test for blood.

Answer 28

True.

Question 29

What are the two microcrystal tests for blood confirmatory tests?

Answer 29

* Teichmann test * Takayama test

Question 30

What is the purpose of species determination tests?

Answer 30

To determine the species of blood using antigen/antibody interactions.

Question 31

What does the Precipitin Ring Test determine?

Answer 31

Whether there is a reaction between anti-human antibodies and human antigens in blood.

Question 32

What is the significance of the D antigen?

Answer 32

Determines Rh factor; Rh positive individuals have the D antigen.

Question 33

Fill in the blank: Type O blood has both _______ and _______ antibodies.

Answer 33

anti-A, anti-B.

Question 34

What is the role of seminal acid phosphatase (SAP) in semen testing?

Answer 34

Presumptive test for seminal fluid.

Question 35

What is the confirmatory test for semen?

Answer 35

Microscopic identification of sperm.

Question 36

What is prostate-specific antigen (PSA)?

Answer 36

Secreted into semen by the prostate gland; can be detected using antibody-antigen tests.

Question 37

What items of physical evidence should be collected from a sexual assault victim?

Answer 37

* Pubic combings * Pubic hair controls * External genital swabs * Vaginal swabs * Cervix swabs * Rectal swabs * Oral swabs * Blood sample * Buccal swab * Fingernail scrapings * Urine specimen * All clothing

Question 38

What should clothing collected from a sexual assault victim be packaged in?

Answer 38

Paper bags, not plastic.

Question 39

What is the persistence duration of sperm with tails in the vagina?

Answer 39

~4 to 6 hours.

Question 40

What enzyme is a presumptive test for saliva?

Answer 40

Alpha-amylase.

Question 41

What indicates the presence of urine?

Answer 41

Creatinine.

Question 42

What indicates the presence of fecal matter?

Answer 42

Urobilinogen.

Question 43

What are enzyme markers in forensic serology?

Answer 43

Enzymes found in blood and other body fluids that survive the drying process and are forensically useful.

Question 44

Define polymorphism in the context of forensic serology.

Answer 44

A genetic trait that has more than one form.