Chapter 14: Serology

Question 1

Describe how polyclonal antibodies are produced in animals.

Answer 1

Polyclonal antibodies are produced in animals by injecting the antigen combined with a protein into the animal, leading to the production of a series of different antibodies designed to attack specific sites on the antigen.

Question 2

Define monoclonal antibodies and how they differ from polyclonal antibodies.

Answer 2

Monoclonal antibodies are a more uniform and specific collection of antibodies designed to combine with a single antigen site. They differ from polyclonal antibodies, which are a collection of antibodies produced in response to an antigen injection in animals.

Question 3

How does the Enzyme-multiplied immunoassay technique (EMIT) work in detecting drugs in urine?

Answer 3

In EMIT, antibodies that bind to a specific drug are added to the subject’s urine, followed by adding a chemically labeled version of the drug. A competition occurs between the labeled and unlabeled drug to bind with the antibody, allowing for drug detection.

Question 4

Describe the Kastle-Meyer colour test for determining blood presence.

Answer 4

The Kastle-Meyer colour test is a preliminary test for determining blood presence, where a positive result, indicated by a deep pink color, is highly indicative of blood due to the presence of hemoglobin.

Question 5

How does the Luminol test work in detecting blood traces?

Answer 5

The Luminol test, also known as the Blue star test, is used to search for trace amounts of blood. It produces luminescence in darkened areas and is highly sensitive, capable of detecting diluted blood up to 100,000 times.

Question 6

Describe the precipitin test in forensic science.

Answer 6

The precipitin test determines whether a stain is of human or animal origin by using antisera to determine the species origin of a questioned blood stain.

Question 7

How does the gel diffusion technique work in forensic analysis?

Answer 7

The gel diffusion technique takes advantage of the movement of antibodies and antigens on an agar plate to determine if a blood stain is human. If human, a line of precipitation forms where antigens and antibodies meet.

Question 8

Define gene and chromosome in the context of heredity.

Answer 8

A gene is the basic unit of heredity, composed of DNA controlling genetic traits. A chromosome is a threadlike structure in the cell nucleus where genes are located.

Question 9

What is an allele and how does it relate to genes?

Answer 9

An allele is any of several alternative forms of a gene at a particular locus on a chromosome. Alleles can influence characteristics like eye color or blood type.

Question 10

How do heterozygous and homozygous gene pairs differ?

Answer 10

A heterozygous gene pair is made up of two different alleles, while a homozygous gene pair consists of two identical alleles.

Question 11

Describe the process of fertilization in terms of chromosomes.

Answer 11

In fertilization, a sperm and an egg combine, each contributing 23 chromosomes to form a zygote that develops into the offspring, transmitting hereditary material through genes located on chromosomes.

Question 12

What is the best way to locate and characterize a seminal stain in forensic analysis?

Answer 12

Perform the acid phosphatase color test.

Question 13

Describe the process of paternity testing using DNA test procedures.

Answer 13

It can raise the odds of establishing paternity beyond 99%.

Question 14

How can forensic scientists link seminal material to an individual in sexual assault cases?

Answer 14

DNA Typing

Question 15

What items of physical evidence are collected from a sexual assault victim during a medical examination?

Answer 15

Pubic combings, pubic hair controls, external genital swabs, vaginal swabs, cervix swabs, rectal swab, oral swabs, swabs of body areas, head hairs, blood sample, buccal swab, fingernail scrapings, urine specimen, all clothing.

Question 16

Do all outer and undergarments need to be carefully removed and packaged separately in forensic evidence collection?

Answer 16

Yes, they should be carefully removed and packaged separately in paper bags, not plastic bags.

Question 17

Describe the persistence of seminal constituents in the vagina.

Answer 17

Motile sperm can last 4 to 6 hours, while non-motile sperm can survive for 3 to 6 days. Seminal acid phosphatase can be detected for less than 48 hours, and prostate-specific antigen for less than 72 hours.

Question 18

What precautions should be taken when packaging biological evidence?

Answer 18

Wearing disposable latex gloves, avoiding plastic or airtight containers to prevent moisture accumulation, packaging stained articles separately in paper bags or well-ventilated boxes, and refrigerating or storing evidence in a cool location until delivery to the laboratory.

Question 19

Define the importance of photographing and sketching biological evidence before collection.

Answer 19

It is crucial to document evidence through photographs and sketches to maintain a clear record of its original state and location.

Question 20

How can physical contact between a victim and assailant impact evidence transfer?

Answer 20

Physical contact can lead to the transfer of blood, semen, saliva, hairs, and fibers between the victim and assailant, potentially crucial for forensic analysis.

Question 21

Do you need to wear disposable latex gloves when handling biological evidence?

Answer 21

Yes, it is required to wear disposable latex gloves when handling biological evidence to prevent contamination and preserve the integrity of the evidence.