Chapter 3: Forensic Biology

Forensic laboratories

_____ provide scientific analysis, evidence evaluation, and consultations to various criminal justice agencies for the investigation of criminal cases.

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They provide expert testimony related to the resolution of criminal cases to the courts.

Crime scene investigation

Functions in evidence recognition, documentation, collection, and preservation.

Latent print examination

Functions in the analysis of friction ridge detail in fingerprints.  Activities include visualization, recording, comparison, storage, and recovery of these prints.

Controlled substance analysis

Functions as the Identification and quantification of drugs present in submitted evidence.

Postmortem toxicology

Determination of concentrations of substances and their metabolites in biological fluids or tissues.

Questioned document examination

Investigation of forgeries, tracings, disguised handwritings, computer manipulation of images, and recovery of altered documents. Analysis of papers, inks, toners, word processors, typewriters, copiers, and printers.

Trace evidence examination

Analysis of transferred evidence such as hairs, fibers, soil, paints, and glass.

Laboratory analysis

_____ utilizes scientific techniques for the examination of evidence, the reconstruction of a crime scene, the identification of biological fluids, and the comparison of individual characteristics of biological evidence.

Individual Characteristics

Refer to the unique characteristics of both the evidence and a reference sample such as fingerprints, which share a common origin to a high degree of certainty.

DNA Polymorphisms

An example of biological evidence possessing individual characteristics.

Current forensic DNA

______ profiling can compare individual characteristics of DNA evidence with a known reference sample.

forensic scientist

A _____ often serves as an expert witness whose testimony provides professional opinions about the evidence analyzed.

Expert Witness

Qualified based on his or her knowledge, skill, experience, training, or education, and may give an opinion to the court that is relevant to the analyses conducted.

medical examiner

A ______ participating in a criminal investigation is often responsible for estimating the time of death.

Forensic Anthropology

It is the identification and examination of human skeletal remains.

examination of bones

An ______may reveal an individual’s origin, sex, approximate age, race, and the presence of a skeletal injury.

forensic anthropologist

A ______ may also assist in creating facial reconstructions to aid in the identification of skeletal remains or may be called on to help collect and organize bone fragments in the course of identifying victims of mass disasters such as plane crashes as well as victims in mass graves discovered after wars or genocides.

Forensic Entomology

The study of insects in relation to a criminal investigation.

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This forensic discipline is valuable for estimating the time of death when the circumstances surrounding the crime are otherwise unknown.

**Forensic Odontologists**

**They** participate in the identification of victims whose bodies are left in an unrecognizable state.

**Forensic Odontologists**

They can analyze the marks left on a victim and compare them with the tooth structures of a suspect to make a comparison.

ABO blood groups

The human ______ were discovered in 1900 by *Karl Landsteiner* in a study of the causes of blood transfusion reactions.

Forensic Serology

Primarily responsible for the detection and identification of biological material on physical evidence.

human genome

The _____ contains all the necessary biological information for cellular and organ structure and function.

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The human nuclear genome, a set of ___ chromosomes, contains approximately 3 billion base pairs.

Human Genome Project

The ________ was initiated in 1990 to sequence the entire human nuclear genome.

genome

The ____ contains genes and intergenic noncoding sequences.

exons

The coding regions of genes are called _____ and are separated by introns.

mRNA

The _____ is a template for protein synthesis in which the sequence is based on a complementary strand of DNA.

splicing

Through the process of _____, the introns are removed and the exons are joined, producing the spliced mRNA form, which can be used for protein synthesis via the translation process.

Tandem Repeats

Repeat units placed next to each other in an array.

Satellite DNA

____ can be found at centromeres and telomeres consisting of regions composed of long stretches of tandem repeats.

Variable Number Tandem Repeats (VNTRs)

Form arrays of tandem repeats with a repeat unit length from several to hundreds of base pairs.

Short Tandem Repeats (STRs)

Also known as *Simple Sequence Repeat*, the repeat unit length can be 2–6 bp long.

Interspersed Repeats

Randomly located throughout the human genome.

Transposition

The mobile elements change their locations.

DNA transposons

During transposition, _____ are excised from one site and inserted at a new site in the genome.

Retrotransposons

________ duplicate themselves during transposition and propagate throughout the genome.

Copy-and-Paste Mechanism

a copy of the original retrotransposons is generated at the new site and the original copy is retained.

Retrotransposition

The transposition of retrotransposons which requires an RNA intermediate.

DNA polymorphisms

The differences between individual genomes that occur at the DNA level.

Sequence Polymorphisms

A DNA polymorphism with alternative forms of a chromosomal locus that differ in nucleotide sequence.

Lengthy Polymorphisms

A DNA polymorphism that differs in the numbers of tandem repeat units.

DNA markers

Many DNA polymorphisms are useful for genetic mapping studies and hence are called _______.

Alleles

Alternative forms of DNA polymorphisms.

Homozygous

The same allele is present in both homologous chromosomes.

Heterozygous

Two different alleles present in homologous chromosomes.

Genotype

A combination of alleles at a given locus.

DNA Profile

The genotype for a panel of analyzed loci.

VNTR technique

In 1984, Sir Alec Jeffreys developed a DNA profiling technique using a *______* involving multilocus profiling and later followed by single-locus profiling.

PCR technique

In the mid-1980s, Kary Mullis and his coworkers developed the *________*, which amplifies a small quantity of DNA.

PCR-based assays

The application of _____ makes forensic DNA analysis possible when only minute quantities of DNA can be recovered from a crime scene, for example, from hairs and cigarette butts.

HLA-DQA1

The first forensic application of a PCR-based assay utilizing SNPs at the _______ locus was developed in 1986.

Amplified fragment length polymorphism (AFLP)

_______ at the D1S80 locus has also been implemented in forensic laboratories

D1S80 locus

A small-size VNTR marker that can be amplified by PCR.

13 STR loci

The United States has selected ______ for the *Combined DNA Index System (CODIS)*. These national DNA databases play important roles in solving criminal cases.

mtDNA

It is maternally inherited genetic material and is therefore particularly useful for human identification.

Y-chromosomal markers

These are paternally inherited so they can be used for paternity testing.