Forensic Science: Hair, Fibers, Drugs, and DNA Case Studies

anagen phase

Active growth stage of hair.

catagen phase

Transitional phase between anagen and telogen.

cortex

Main body of the hair; contains pigment granules.

cuticle

Outer layer of hair; scale structure.

follicle

Structure in skin that produces hair.

follicular tag

Tissue attached to hair root containing nuclear DNA.

hair root

Portion of hair within follicle where growth occurs.

medulla

Central canal of hair; may be continuous, interrupted, or absent.

mitochondrial DNA

DNA passed only from mother; found in hair shaft.

monomer

Single repeating unit of a polymer.

natural fiber

Fibers from plants or animals (cotton, wool).

nuclear DNA

DNA found in cell nucleus; individual-specific.

polymer

Large molecule formed from repeating monomers.

regenerated fiber

Made from cellulose (rayon, acetate).

root

Base of hair inside follicle.

synthetic fiber

Man-made (nylon, polyester).

telogen phase

Resting/shedding phase of hair.

anabolic steroids

Synthetic hormones that build muscle.

analgesic

Pain reliever.

chromatography

Technique for separating chemical mixtures.

club drug

Drug commonly used in nightclubs (MDMA, GHB).

confirmation test

Positive ID test (GC-MS, IR).

depressant

Slows CNS.

fluoresce

Glow under UV light.

hallucinogen

Alters perception and mood.

infrared

Type of electromagnetic radiation.

ion

Charged atom or molecule.

microcrystalline test

Forms crystals for drug identification.

monochromatic light

Light of a single wavelength.

monochromator

Device that isolates specific wavelengths.

narcotic

Pain reliever from opium; causes drowsiness.

physical dependence

Body becomes chemically dependent on a drug.

psychological dependence

Emotional need for a drug.

screening test

Preliminary test (color test).

spectrophotometry

Measures absorption of light by a substance.

stimulant

Speeds CNS; increases alertness.

ultraviolet

High-energy EM radiation.

absorption

Taking in a substance.

acid

pH < 7.

alveoli

Air sacs in lungs where gas exchange occurs.

anticoagulant

Prevents blood clotting.

artery

Carries blood away from heart.

base

pH > 7.

capillary

Microscopic blood vessel.

excretion

Elimination of waste.

fuel cell detector

Device measuring alcohol in breath.

metabolism

Chemical processes in the body.

oxidation

Chemical combination with oxygen.

pH scale

Measures acidity/basicity: 0-14.

preservative

Prevents microbial growth.

toxicologist

Studies effects of toxins/drugs.

vein

Carries blood toward heart.

acid phosphatase

Enzyme indicating semen.

agglutination

Clumping of red blood cells.

allele

Alternative form of a gene.

antibody

Protein reacting with antigens.

antigen

Protein on cell surface triggering immune response.

antiserum

Serum with specific antibodies.

aspermia

No semen.

chromosome

Carries genetic info.

deoxyribonucleic acid

DNA.

egg

Female reproductive cell.

erythrocyte

Red blood cell.

gene

Unit of heredity.

genotype

Genetic makeup.

hemoglobin

Oxygen-carrying protein in blood.

heterozygous

Two different alleles.

homozygous

Two identical alleles.

hybridoma cells

Produce monoclonal antibodies.

locus

Location of a gene.

luminol

Reacts with blood to produce light.

monoclonal antibody

Identical antibodies from hybridoma.

oligospermia

Low sperm count.

phenotype

Physical appearance.

plasma

Liquid portion of blood.

polyclonal antibody

Antibodies from multiple cells; diverse.

precipitin

Antibody-antigen reaction forming solid.

serology

Study of blood and bodily fluids.

serum

Liquid after clotting.

sperm

Male reproductive cell.

X chromosome

Female sex chromosome.

Y chromosome

Male sex chromosome.

amelogenin gene

Determines sex in DNA testing.

amino acids

Building blocks of proteins.

buccal cells

Cheek cells used in DNA collection.

complimentary base pairing

A-T and C-G in DNA.

CODIS

National DNA database.

electrophoresis

Separates DNA fragments by size.

endonuclease

Cuts DNA at specific sites.

hybridization

Binding of complementary DNA strands.

mitochondria

Energy-producing organelles with their own DNA.

multiplexing

Amplifying multiple STRs at once.

nucleotide

Building block of DNA.

PCR

Technique to amplify DNA.

primer

Short DNA used in PCR.

proteins

Made of amino acids.

replication

Copying DNA.

sequencing

Determining DNA base order.

tandem repeat

Repeated DNA sequences.

touch DNA

DNA left from skin cells after contact.