Crime Chapter 3 Hair Test Review

What can you take away from hair comparison?

- Color -length -Diameter -Distribution, shape, and color intensity of pigment -dyed hair has color in cuticle and cortex -bleaching removes pigment and gives a yellow tint -grey hair has no pigmentation -Scale type -Presence or absence of medulla -medullary pattern -Medullary index

Where should hairs be collected from?

- From Victim - Possible suspects - Others who may have deposited hair at the scene

What can one determine from a hair?

-human or animal -Race -Origin of the location on body -Whether the hair was forcibly removed - If the hair has been chemically treated -If drugs have been ingested

How much does hair grow in a month?

1 centimeter a month, 1/2 inch a year

What is the medullary index normally for human hair?

1/3

A women is suspected in a burglary case. Why is it important that the police request 25-50 hairs from this women. She is also suspected of burglary to support a drug habbit.

20(a)- Police need to pull the hair so they will have the follicle still on the hair which could give DNA and give the identity of an individual. 20(b)- obtaining multiple hairs from the woman will give a more accurate picture of the exposure to drugs and other toxins, because the hairs of a single individual very significantly. especially those with a mix of brown and grey 20(c)- if a woman has been off drugs for over a year traces of the drugs will appear in her hair only after roughly 16cm 20(d)- If hairs at a crime scene do not contain DNA they cannot be used to determine the identity of an individual

Control samples?

50- full length hairs from all areas of the scalp 24- full length pubic hairs

Which of the following it most likely a result of hair bleaching?

A yellowish tint to the hair

The period of active hair growth is called the ---- stage.

Anagen

Describe two ways that animal hair differs from human hair.

Animal hairs have different medulla patterns and a different cuticle pattern

List traits for Asian/native American, Caucasian, African/African American?

Asian- Round cross sections Caucasian/ Mexican middle eastern- oval cross sections African/ African American- Flat to crescent cross section, clumping, pigmentation

Which of the following characteristics is found in typical Asian hair?

Dark Medulla

True or False: All hairs on the head of a person are identical?

False

True or false: Hair is composed of a protein called Cellulose?

False

Hair shaft contains an abundant or -----, inherited from ------.

First blank- Mitochondrial DNA second blank- From the mother

A woman's body was found in the woods! After a hair collection was made the lab determined that the ends of the hair were dyed. From the base of the root to the dyed hair it was 8mm! They determined that the hair was dyed on August 1,2004. assuming hair grows .44 mm/day, on what date did they girl die?

Hair grows .44 mm/day. The woman's hair grew 4 mm since august 1, 2004 4mm/.44mm/day= 9 9 days from august 1 is august 10th,2004

Describe the structure of hair. Include in your answer the terms follicle, medulla, cortex, and cuticle.

Hair grows from a follicle found in the skin. It is composed of the inner medulla, surrounded by the cortex and protected by the outside cuticle

What is the Catagen phase?

Hair is not growing; a resting phase

What is the anagen phase of hair growth?

Hair that is actively growing; lasting 3 to 5 years (80-90% of a persons hair will be in this phase)

What is the telogen phase?

Hair that is dying and ready to fall out; lasting two to six months

Human hair has which type(s) of cuticle?

Imbricate

Why is hair considered class evidence?

It is class evidence because there is no source of DNA (skin cells) Without DNA hair can only indicate what racial group the individual may belong to.

The hair shaft is composed of the cuticle, cortex, and.....?

Medulla

calculate the medullary index of a hair that has a diameter of 110 microns wide and a medulla that measures 58 microns. Also, is it human or animal?

Medullary index= diameter of medulla / diameter of hair (=58 microns/110 microns) =0.527=.53 (most likely animal hair) more than .5

What cross section makes hair Curly, kinky, or straight?

Oval- Curly Round- straight Crescent Moon- Kinky

Which part(s) of a hair can be analyzed for DNA?

Root

Neutron activation analysis can check hair for the presence of....?

Silver

The cuticle scales of the hair always point toward the....?

Tip of the hair

True or False: The cortex may contain pigment granules

True

True or false: The hair shaft of the hair is considered class evidence in a trial?

True

Which factors are used to calculate the medullary index of the hair?

Width of medulla and the width of the hair

What is the medullary index for animal hair?

greater than 1/2

Although variations can occur, which of the following best describes northern European hair?

straight and even distributed granules