criminalistics exam 3

What is forensic serology?

Laboratory testing involving antigen-antibody reactions.

What is an antigen?

A substance recognized by an antibody.

What is an antibody?

A protein that reacts with a specific antigen.

What is plasma?

The fluid portion of blood.

What is the function of red blood cells?

Carry oxygen to tissues and carbon dioxide to the lungs.

What is the function of white blood cells?

Help defend the body against infection.

What is the function of platelets?

Help blood clot.

What determines ABO blood type?

The antigens present on the surface of red blood cells.

What antigen does type A blood have?

A antigen.

What antigen does type B blood have?

B antigen.

What antigens does type AB blood have?

Both A and B antigens.

What antigens does type O blood have?

Neither A nor B antigens.

What happens when anti-A serum reacts with A antigens?

Agglutination, or clumping, occurs.

What happens when anti-B serum reacts with B antigens?

Agglutination, or clumping, occurs.

What does agglutination mean?

Clumping of cells caused by an antigen-antibody reaction.

Is ABO blood type an individual or class characteristic?

Class characteristic.

What percentage of the population has type O blood according to the slides?

43%.

What percentage of the population has type A blood according to the slides?

42%.

What percentage of the population has type B blood according to the slides?

12%.

What percentage of the population has type AB blood according to the slides?

3%.

What three questions are asked when examining blood evidence?

Is it blood? Is it human? Can it be associated with an individual?

What is a presumptive blood test?

A test that suggests a substance may be blood.

What color does a positive phenolphthalein blood test produce?

Deep pink.

What does luminol detect?

Possible blood through a luminescent reaction.

What is Bluestar used for?

Detecting possible blood through luminescence.

What are Takayama and Teichmann tests?

Microcrystal tests used to identify blood.

What does the precipitin test help determine?

Whether blood is human or animal.

What is gel diffusion used for in serology?

Helping distinguish human blood from animal blood.

What is an immunoassay?

A test using antigen-antibody reactions to screen substances.

What can immunoassays screen for?

Drugs in blood or urine.

Are immunoassay results presumptive or confirmatory?

Presumptive.

What is a confirmatory drug test example from the slides?

GC-MS.

What does DNA stand for?

Deoxyribonucleic acid.

What does DNA carry?

Genetic information.

What is a gene?

A segment of DNA containing instructions for a functional product.

How many chromosomes do most nucleated human cells contain?

46 chromosomes arranged in 23 pairs.

How many chromosomes does an egg contain?

23 unpaired chromosomes.

How many chromosomes does a sperm contain?

23 unpaired chromosomes.

How many chromosomes does a zygote contain?

46 chromosomes arranged in 23 pairs.

Which sex chromosome does an egg contribute?

X chromosome.

Which sex chromosome can a sperm contribute?

X or Y chromosome.

What chromosome combination is typically female?

XX.

What chromosome combination is typically male?

XY.

Do mature red blood cells contain nuclear DNA?

No, they lack a nucleus.

What is a DNA nucleotide made of?

A sugar, phosphate group, and nitrogenous base.

What are the four DNA bases?

Adenine, thymine, cytosine, and guanine.

Which DNA base pairs with adenine?

Thymine.

Which DNA base pairs with cytosine?

Guanine.

What is the shape of DNA?

Double helix.

What does a codon consist of?

Three DNA bases.

What does a codon specify?

An amino acid.

What do amino acids combine to form?

Proteins.

What is DNA replication?

The process of making a copy of DNA.

What enzyme adds complementary DNA bases during replication?

DNA polymerase.

What does PCR stand for?

Polymerase Chain Reaction.

What is the purpose of PCR?

Amplifying DNA by making many copies of a selected region.

What machine is used for PCR?

Thermal cycler.

What do primers do in PCR?

Identify the DNA region to be copied.

What does STR stand for?

Short Tandem Repeat.

What is an STR?

A short DNA sequence repeated next to itself.

Why are STRs useful in forensic DNA analysis?

The number of repeats can vary between individuals.

What is a locus in DNA profiling?

A specific location on a chromosome.

What is multiplexing in DNA analysis?

Examining multiple STR locations in one analysis.

What does capillary electrophoresis do?

Separates DNA fragments based on size.

What does gel electrophoresis do?

Separates DNA fragments based on size.

Which electrophoresis method is commonly used today according to the slides?

Capillary electrophoresis.

What is an electropherogram?

A graph displaying DNA profiling results.

What does CODIS stand for?

Combined DNA Index System.

What is CODIS?

A database system containing DNA profiles.

What types of profiles can CODIS contain?

Convicted offenders, crime-scene evidence, and missing persons.

What agency oversees the national CODIS system?

The FBI.

What is the amelogenin marker used for?

Sex determination in DNA profiling.

What amelogenin result is described for XX?

One peak.

What amelogenin result is described for XY?

Two peaks.

Why is PPE important when collecting DNA evidence?

It helps prevent contamination.

Why should damp biological evidence not be packaged in plastic?

Moisture can encourage biological degradation.

What packaging is used for biological evidence according to the slides?

Paper packaging.

What is a buccal swab used for?

Collecting a known DNA reference sample.

What is AFIS?

Automated Fingerprint Identification System.

What does AFIS do?

Searches fingerprint databases and returns possible matches.

Does AFIS make the final fingerprint identification?

No, a trained examiner evaluates the possible match.

What are the three fundamental fingerprint principles?

Individual characteristics, permanence, and unique ridge patterns.

What does fingerprint permanence mean?

Fingerprint ridge patterns remain unchanged throughout a person's lifetime.

What does fingerprint individuality mean?

Fingerprint ridge details distinguish one print from another.

What are the three basic fingerprint patterns?

Loops, whorls, and arches.

What is a loop fingerprint?

A pattern in which ridges enter and exit on the same side.

What is a whorl fingerprint?

A pattern with circular or spiral-like ridges.

What is an arch fingerprint?

A pattern in which ridges enter one side and exit the other.

What is the most common fingerprint pattern?

Loop.

What are fingerprint minutiae?

Small ridge characteristics used for comparison.

What is a ridge ending?

A fingerprint ridge that stops.

What is a bifurcation?

A fingerprint ridge that splits into two.

What is an enclosure?

A ridge that divides and then rejoins.

What is a ridge island?

A short isolated fingerprint ridge.

What does ACE-V stand for?

Analysis, Comparison, Evaluation, and Verification.

What happens during fingerprint analysis?

The examiner assesses the questioned print and its quality.

What happens during fingerprint comparison?

The questioned print is compared with a known print.

What happens during fingerprint evaluation?

The examiner determines identification, exclusion, or inconclusive results.

What happens during fingerprint verification?

Another examiner independently checks the conclusion.

What is the Henry classification system?

An early system for organizing fingerprints by pattern.