forensics hair and fiber

5. Be able to give an example of the type of animal for each cuticle pattern.

-Coronal: rodents -Spinous: cats, seals, and minks -Imbricate: humans

8. Be able to identify the cuticle cortex and medulla of a hair

-Cuticle: outside covering made of overlapping scales (scales point towards the tip of the hair and scales differ among species of animals which are named based on their appearance) -Cortex: inner layer made of keratin and embedded with pigment, also contains air sacs called cortical fusi. --Medulla: inside layer running down the center of the cortex

17. Hair can be classified as several different types of evidence. Identify the types and explain why.

-Individual Evidence: when the follicle is attached, Class -Evidence: when the follicle is unattached

7. Be able to identify the various medullary patterns when viewed through a microscope.

-Interrupted: not all the same size -Fragmented: equal size -Continuous -Absent: not present

6. What part(s) of a hair can be analyzed for nuclear DNA? Mitochondrial DNA?

-Nuclear: Follicle -Mitochondrial: Shaft

3. How can medullary index be used to determine if the hair is animal or human?

It's determined by measuring the diameter of the medulla and dividing it by the diameter of the hair. -Human hair is generally less than 1/3. -Animal hair is usually greater than 1/2

9. What protein gives hair its color?

Keratin

What protein makes it waterproof?

Keratinocytes

22. What are the two most common manmade fibers?

Polyester and nylon

12. What lens should be in place when storing a microscope?

Scanning lens

13. What is the working distance of a lens? Be able to identify the relationship between the working distance of an objective lens and its power.

The free space between the object and the lens

23. How can fibers aid in crime scene analysis?

The number fabrics produced with any one fiber type and color is extremely small. The number of fibers on the clothing of a victim identified as matching the clothing of a suspect is important in determining actual contact. The greater the number of fibers, the more likely that contact actually occurred between these individuals

19. What affects how easily fibers are transferred from one place to another.

type and length

11. Given the diameter of a field of view be able to calculate the diameter of field of view of a different power on the same microscope

Field of View= Field Number (FN)/Objective Magnification

21. For each of the following list its specific source: wool, linen, silk, angora, cashmere, cotton, linen

Wool: sheep Linen: flax plant Silk: silk worm Angora: rabbit Cashmere: goat Cotton: plant Linen: flax plant

15. How do you prepare a slide to examine the cuticle pattern?

1.) Paint clear nail polish on a glass slide 2.) When the polish begins to dry place a hair on the polish 3.)When its almost dry lift off the hair and observe the scale imprints

16. How do you prepare a slide to examine the medullary pattern?

1.)Make a wet mount slide using glycerin instead of water 2.)Place the hair directly on top of the glycerin 3.)Place a cover slip on top of the hair and glycerin

20. List at least three common sources of fibers at a crime scene.

Clothing, drapery, and carpeting

1. What factors are used to determine the medullary index of a hair?

The ratio between the diameter of the entire hair, medullary index= (medulla diameter) / (hair diameter) (this is a dimensions unit)

2. Given a photograph through a microscope at a given magnification and field of view size, be able to calculate the diameter of the hair, the diameter of the medulla, and the medullary index

medullary index = medulla's width/entire hair's width

18. Fibers can be....

natural or manmade