Forensic Biology

accreditation

The process by which a forensic laboratory is officially recognized for meeting specific standards of quality and competence in its testing and analysis procedures.

Laboratory Validation

The process of ensuring that a laboratory's methods and procedures are scientifically sound and suitable for their intended use often involving testing and documentation.

Quality Assurance

A systematic process to ensure that laboratory procedures and results meet established standards and regulations, thereby enhancing reliability and accuracy.

Quality Control

The procedures and practices implemented to monitor and maintain the quality of laboratory processes and results, ensuring they meet specified standards.

Proficiency Testing

A method used to evaluate a laboratory's performance by comparing its results to those from other laboratories or established standards, ensuring accuracy and reliability.

Certification

The process by which a laboratory demonstrates its competence and compliance with specific standards, often through third-party evaluation and validation.

Probative

Having the ability to prove or demonstrate something in a court of law, particularly regarding the relevance and reliability of evidence.

Locard’s Exchange Principle

The principle states that the perpetrator of a crime will bring something into the crime scene and leave with something from it, thus providing forensic evidence.

Polymorphism

The occurrence of two or more distinct forms or alleles in a population is often used in genetic studies to analyze variation among individuals.

Tandem repeats

are repeating DNA sequences adjacent to each other, often used in genetic profiling and analysis.

Minisattelites (Variable Number Tandem Repeat)

are a type of tandem repeat that consists of repeating sequences of 10 to 100 base pairs in length, commonly used in DNA fingerprinting and genetic studies.

microsatellite (Short Tandem Repeat)

a type of tandem repeat consisting of sequences of 1 to 6 base pairs in length, widely utilized in genetic profiling and population studies.

Mobile Elements (Interspersed Repeats)

are DNA sequences that can change their position within the genome, often contributing to genetic diversity and evolution.

CODIS

a national database used for storing and comparing DNA profiles in criminal investigations.

Transcellular Fluid

the fluid found within cells, including cytoplasm and organelles, crucial for cellular function and communication.

Erythocytes

are red blood cells responsible for transporting oxygen throughout the body.

Leucocytes

are white blood cells that play a key role in the immune response by fighting infections and foreign substances.

Plasma

the liquid component of blood that carries cells, nutrients, hormones, and waste products.

Extracellular Nucleic Acid

refers to DNA or RNA found outside of cells, often released during cell death or in response to injury, playing a role in various biological processes.

Extracellular vesicles (exosomes and microvesicles)

are small membrane-bound particles released from cells that facilitate intercellular communication and transport biomolecules.

Apoptotic Bodies

are membrane-bound vesicles produced during apoptosis, containing cellular components that can be phagocytosed by other cells, playing a role in the removal of dying cells.

microRNAs

small, non-coding RNA molecules that regulate gene expression by binding to target messenger RNAs (mRNAs), influencing their stability and translation.

touch evidence

refers to biological material left behind during physical contact, such as skin cells or sweat, that can be analyzed for forensic purposes.

transfer DNA

is DNA that is transferred from one source to another, often found on items such as weapons or personal belongings, and can provide evidence of a person's presence at a crime scene.

medulla, cortex, cuticle

are the three main layers of a hair strand, each with distinct structures and functions that can provide important forensic information.

hair follicle

is the part of the hair that is embedded in the skin, from which hair grows, and contains cells that can provide DNA for forensic analysis.

anagen, catagen, telogen

are the three phases of the hair growth cycle, each representing different stages of hair development and shedding.

osteocytes

are mature bone cells that maintain bone tissue and play a role in the regulation of bone density and mineral content.

dental pulp and cementoblasts

are components of teeth, with dental pulp containing nerves and blood vessels, while cementoblasts are cells that produce cementum, a substance that covers the tooth's root.

immunogen

is a substance that induces an immune response, triggering the formation of antibodies.

Antigen

is a molecule or substance that is recognized by the immune system and can provoke an immune response, often by binding to antibodies.

antibodies (immunoglobulin)

are glycoproteins produced by plasma cells in response to antigens, playing a crucial role in the immune response by identifying and neutralizing pathogens.

Isotypes

are variants of a particular chemical element that have the same number of protons but different numbers of neutrons, resulting in different atomic masses.

Polyclonal Antibody

is a mixture of antibodies produced by different B cell lineages in response to an antigen, recognizing multiple epitopes on the same antigen.

Monoclonal Antibody

is an antibody produced by identical immune cells that are clones of a unique parent cell, targeting a specific epitope on an antigen.

Avidity

refers to the overall strength of binding between an antibody and an antigen, taking into account the multiple binding sites and affinities involved.

Affinity

refers to the strength of the interaction between a single antibody binding site and its specific epitope on an antigen.

Epitope

a specific part of an antigen that is recognized and bound by an antibody.

agglutination

the clumping together of particles, such as cells, in response to an antibody.

Precipitation

The formation of a solid from a solution during a chemical reaction, often involving antibodies and soluble antigens.

class vs individual characteristics

Class characteristics refer to features shared by a group of items, while individual characteristics are unique to a specific item, aiding in forensic identification.

presumptive and confirmatory assays

Presumptive assays indicate the potential presence of a substance, while confirmatory assays definitively identify that substance.

ELISA

Used to detect proteins or antigens in fluids, applied in forensic toxicology and serology.

lateral flow immunoassay

Rapid, field-friendly tests like pregnancy tests or forensic body fluid identification kits.

antibody titration

Determines antibody concentration in a sample, relevant for forensic serology and immunoassays.

hemoglobin

Oxygen-carrying blood protein, target for blood detection methods.

Oxidation-Reduction

Basis of many forensic presumptive tests (e.g., benzidine test for blood).

Colorimetric Assays

Tests based on color changes (e.g., Kastle-Meyer test for blood).

Chemiluminescence Assay

Light-emitting reactions used in forensic blood detection (e.g., luminol).

Fluorescence Assay

Uses fluorescent dyes to detect biological substances (e.g., ALS for body fluids).

False Positive

A test incorrectly indicates the presence of a substance.

False Negative

A test fails to detect a substance that is present.

Seminal Fluid

Contains sperm cells and seminal plasma, tested with PSA, acid phosphatase, and sperm-specific markers.

Acid Phosphatase

Enzyme present in high levels in semen, used in presumptive semen tests.

Prostate Specific Antigen

Biomarker for semen identification.

oligospermia

Low sperm count, relevant in forensic fertility cases.

azoospermia

Absence of sperm in semen, relevant in forensic investigations of sexual assault.

semenogelin I and II

Major semen proteins, often targeted in forensic tests.

Christmas tree stain

Microscopic sperm identification stain (nuclear fast red & picroindigocarmine).

immunochromatographic assays - RSID, HemDirect, PSA Semiquant

Includes RSID (Rapid Stain Identification), HemDirect, and PSA Semiquant, used for blood, semen, and saliva detection.

salivary amylase

Key enzyme in saliva, detected for forensic saliva identification.

glycogenated and parabasal cells

Found in vaginal secretions, used for differentiation in forensic casework.

D-dimer

A fibrin degradation product, used in forensic wound age estimation and clot analysis.