FSC 301 Study Guide for Quiz 3 and Exam 3

What is an alternate light source and what it is used for?

it is a specialized device in forensic science to enhance the visualization of evidence that might not be visible under normal lighting conditions. it is used for the detection of biological fluids, enhancement of latent fingerprints, and much more!

True or False: When an alternate light source is used in a piece of evidence, only the semen will fluoresce.

False. Other substances such as sweat and saliva will also fluoresce under specific wavelengths of light.

True or False: Large piece of evidence such as bed sheets are examined first by acid phosphatase test before other methods are employed.

False. Typically they are examined first by visual inspection and/or an alternate light source to locate potential stains. Once potential areas are identified, specific tests such as the AP test may be conducted to screen for the presence of semen.

The process of screening large piece of evidence such as panties for the presence of seminal fluid is commonly called as _________.

mapping.

Leeuwenhoek — year 1677

became the first person to observe and describe sperm cells (spermatozoa)

The Dutch scientist Leeuwenhoek presented his findings regarding spermatozoa to this society:

Royal Society of London

What are the five things the Dutch scientist explained in his speech to the Philosophical Transactions of the Royal Society of London regarding his discovery of spermatozoa (characteristics and description).

1. discovery of spermatozoa

2. movement of spermatozoa

3. sperm structure

4. quantity of sperm cells

5. reproductive implications

List any ten items of evidence that are collected during a sexual assault examination.

1. victim’s clothing

2. swabs for biological samples

3. pubic hair combing

4. head hair samples

5. fingernail scrapings/clippings

6. buccal swab (DNA sample from victim)

7. torn or damaged clothing

8. external body swabs

9. photographs of injuries

10. evidence from the assault location1

The three presumptive tests that can be used to detect the presence of seminal fluid.

1. Acid Phosphatase (AP) Test

2. Fluroescence Test

3. Prostate-Specific Antigen (PSA) Test

The enzyme acid phosphatase is found in approximately ______ times more in semen compared to other body fluids.

400

True or False: Acid phosphatase is an enzyme that is active at a pH above 7.

False. It is an enzyme that is active at an acidic pH, typically around pH 4.5 to 6.0.

Acid Phosphatase can also be called as _______ _________.

prostate-specific acid phosphatase

True or False: Acid Phosphatase is highly stable at 37 degrees Celsius.

True

The average acid phosphatase concentration found in human seminal fluid is ____ king-armstrong units/100 mL semen.

1000

True or False: In some instances it is possible to get a positive AP test result and negative sperm search.

True

What are the two reasons that one might get a positive AP test result and negative sperm search?

1. degraded or old semen

2. presence of seminal fluid without sperm

The name of the purple color compound identified in the AP spot test.

“purple color complex” or more specifically “Fast Blue B”

What is AP mapping (or press test)

It is a technique used in forensic science to screen for the presence of seminal fluid on an item of evidence. It involves applying a reagent containing sodium alpha-naphthyl phosphate and Fast Blue B dye to the suspected area on the evidence. If acid phosphatase is prsent, the enzyme catalyzes the reaction, producing a purple color.

normal sperm count

15 million sperm per milliliter

39 million or more per ejaculation is considered normal

oligospermic

low sperm count

azoospermic

no sperm present in the semen

aspermic

no semen produced during ejaculation

What are the three tests that can be used for seminal fluid/semen identification?

1. Acid Phosphatase (AP) Test

2. Prostate-Specific Antigen (PSA) Test

3. Fluorescence Test

Spermatozoa stains

help forensic scientists confirm the presence of sperm in evidence, such as clothing, bedding, or swabs taken from a sexual assault victim

This part of the spermatozoa provides protection to the sperm head.

acrosome

The purpose of the mitochondria in a spermatozoa

essential for energy production and motility, making them vital for the sperm’s ability to move efficiently and successfully fertilize an egg

The two key characteristics used in the identification of spermatozoa using a microscope

1. morphology (shape and structure)

2. motility

The number of chromosomes present in a spermatozoa

23 chromosomes

The anterior opaque part of the spematozoon head is called ________.

acrosome

The mitochondria are located in this part of the spermatozoa

midpiece

The total length of a human spermatozoon is _____ micron.

50-60

the length of the head of the human spermatozoon is ______ micron.

5-6

The concentration of PSA in blood is usually at or below ______ ng/ml in normal male.

4

composition of florence cyrstal test reagent

1. saturated copper sulfate

2. acetic acid

3. water

ouchterlony double immunodiffusion test

used to detect the presence of specific antigens or antibodies in a sample. involves the diffusion of antigen and antibody through a gel medium to form a precipitate at the point of optimal antigen-antibody interaction

define king-armstrong unit (for acid phosphatase)

it is a unit of measurement used to quatify the activity of the enzyme acid phosphatase in a sample.

the two end products that result in the digestion of sodium alpha naphthyl phosphate by acid phosphatase

1. alpha-naphthol

2. inorganic phosphate

PSA stands for ______.

Prostate-Specific Antigen

IN the p30 antigen, the p refers to _____ and the 30 refers to _______

p: prostate

30: molecular weight

spermatozoa parts and measurements

Head: 5-6 micrometers

Midpiece: 5-7 micrometers

Tail: 40-50 micrometers

the molecular weight of the P30 antigen is ____ daltons

30,000

True or False: P30 antigens will react with anti-PSA antibodies

true

The company that manufactures the Aba card one step PSA test kit is _____.

abacus diagnostics

The principle involved in the ABA card one step test kit for the identification of seminal material is ….

uses immunochromatography to detect the presence of PSA, which is an indicator of seminal material in a sample. the presence of a test line indicates a positive result, confirming the presence of semen.

The three antibodies present in the ABA card one step test kit for the identification of seminal fluid are:

1. monoclonal anti-psa antibody

2. anti-psa antibody (immobilized)

3. control line antibody

True or False: Vasectomized individuals willhave normal sperm production.

True.

What is high dose hook effect? what happens during this process? How to correct this problem in the PSA identification test?

the high dose hook effect in the PSA identification test occurs when a very high concentration of PSA leads to saturation and diminished signal, resulting in a false negative. can be corrected by diluting the sample and retesting to obtain accurate results.

True or False: high dose hook effect is caused the presence of small amount of antigens.

false

The following is the result of the different tests for seminal fluid. Based on these results, what will be your conclusion?

Results:

i. AP screening — negative; ii. Sperm search — negative; iii. PSA screening — positive

Your conclusion:

a) semen absent

b) semen present

c) semen present but cannot be confirmed

d) inconclusive results because two tests are negative

semen absent

50. The following is the result of the different tests for a swab submitted in a sexual assault test kit. Based on these results, what will be your conclusion? (1)

Results:

i. AP screening – positive; ii. Sperm search – negative; iii. PSA screening – negative

Your conclusions:

a) semen present

b) semen absent

c) spermatozoa present

d) inconclusive result because two tests are negative

semen absent

The amount of the enzyme amylase found in saliva is _____ times more compared to other body fluids.

50

The appearance of blue color indicates the presence of ______ in the saliva test plate using agarose petri dishes.

amylase

What are the significance of the clear area and blue area in the agarose petri dish test for saliva?

i. Clear area:

ii. Blue area:

Clear: indicates the presence of amylase and confirms the presence of saliva

Blue: indicates the absence of amylase activity

True or False: higher concentrations of amylase indicates the presence of semen.

false

True or False: In the salivary amylase test, iodine is used for staining the agarose.

true

1.               You are using the following samples and antibodies in an immunodiffusion experiment. Find out the precipitin band formation pattern in the plate.

 

1. Center well — anti PSA antibodies

2. Known human semen

3. Cattle semen

4. rabbit serum

5. human blood

6. known human semen

7. known human serum

You can number the outer wells.