forensic quiz 2

characteristics of hair

adhere to surfaces; doesnt decompose; class evidence

Functions of hair

Regulates body temperature; decreases friction; protect skin against sunlight; acts as a sense organ

anagen stage

Active growth (80-90% of all hair)

Catagen stage

Hair stops growing

telogen stage

Dormant and resting; hair is shed at the end of the stage

follicule

Cub-shaped structure that contains a network of blood vessels that supply nutrients

Contains cells with DNA

Oil gland

hair shaft

Non Growing part of hair

Contains mitochondrial DNA

Composed of a protein called Keratin

inner medula

Center of the hair

cortex

The largest part of the hair shaft that contains the melanin granules (gives the hair the color)

Outer cuticle

Protects the inner layers; made up of overlapping scales

DNA source

Hairs with an attached follicle or root

Contain nuclear DNA

Provide individual evidence

without root or follicule

Contain mitochondrial DNA

Reveal family relationships

6 types of hair on body

Head, eyebrows and eyelashes, beard and mustaches, under arm, body hair, pubic

treated hair

bleaching, dyeing, Determining PMI (post-mortem interval) - can possibly tell when someone died based on treated hair

Hair grows at the rate of 1.3 cm/month or .44mm a day but can be affected by many other factors like age, stress, and hormones

key physical characteristics, but only generalities

European (straight or wavy, C/S oval or round)

Asian (straight, C/S round with large diameter)

African (kinky or curly, C/S flattened with small diameter)

pigmentation

Human hairs are usually one color along the length and denser towards the cuticle

cuticle

Human scales are flattened narrow

medullary index

Ratio of the diameter of the medulla to the diameter of the entire hair (animals are thicker)

Collecting hair as trace evidence

Photograph in situ; use clean forceps

macroscopic analysis

Seen with a naked eye; length, color, and curliness

microscopic analysis

Determines human or non-human; shows presence of dies, hair, treatments

IRMS

Water and food from a specific location will have the same isotope signature as the region/environment

The longer the hair the more information can be gained

forensic dna analysis

It has the potential to individually identify a particular suspect

Forensic DNA analysis identifies individuals, closely related relatives, remains of mass disaster war victims, and missing persons.

dna profiling

Techniques that identifies a person based on their genetic code; No two people share the same DNA, Exception is identical twins, DNA is inherited from the mother and father, Can be used to determine kinship (closely related individuals)

CODIS

a database of arrestee’s DNA, collects, analyzes, and communicated criminal DNA information among law enforcement agencies, maintains DNA profiles of missing persons and unidentified human remains period

limiting factors

cost, time log, backlogs, instrumentation

DNA identification act

provides funds to improve labs and communication between law enforcement organizations period; new rapid dna testing kits (90 min)

science of dna

all human cells contain dna (except red blood cells), contains dna in cells nucleus (nuclear dna), structure of dna is a double helix which resembles a twisted ladder

chromosomes

Structure where nuclear DNA is stored.

46 chromosomes are found in the human body. They are composed of tightly coiled DNA molecules wrapped around proteins.

Each parent contributes 1 member of each pair of the 22 chromosomes plus one sex chromosome (male XX, female XY)

Your genetic code is composed of half of your mother's chromosomes and half of your father's chromosomes.

genes

basic units of heredity; human gene DNA sequences are 99.% the same, the 0.1% is what makes us different; alternative forms of a gene are alleles

precautions to avoid contamination

Use disposable instruments

Wear disposable gloves and change them often

Avoid touching areas where DNA may exist

Avoid touching your face

Never put two sources of DNA in the same bag

preservation of dna evidence

Keep DNA evidence dry, cool, and out of direct sunlight during transportation and storage

Moisture

Humidity

serologist

One who specializes in the analysis of blood serum, saliva, semen, and other bodily fluids; determine if source is human

mtDNA

is responsible for cellular respiration and energy.

Only the mother can pass mtDNA to her offspring and thus maternal ancestry can be traced using this type of DNA.

Unlike the limited amount of DNA found in nuclear DNA, the mitochondria can supply thousands of copies.

genetic genealogy

ancestry kits; mouth swab; family tree; public genealogy databases; relatives with partial matches; some consider violation of 4th amendment right to privacy

dna phenotyping

Through computer analysis a composite sketch of a person, including sex, eye color, skin tone, hair color, freckling, and facial structure is produced based on their genetic profiles.

Forensic artwork using age progression programs shows changes to the person over time including facial hair, loss of hair, glasses, wrinkles, and body weight.