Hair & Fiber Evidence Hair Biology keratin 1. Hair is composed of the protein ________________, which is also the primary component of finger and toe nails. follicle _________. Hair is produced from a structure called the hair _____________________. Humans develop hair follicles during _______________ development, and no new follicles are produced after birth. fetal pigments 2. Hair color is mostly the result of _______________, which are chemical compounds that reflect certain shape texture wavelengths of visible light. Hair ____________ (round or oval) and ______________ (curly or straight) is genes influenced heavily by ______________. The physical appearance of hair can be affected by alteration _nutritional____status and intentional ____________________ . root 3. In order to test hair evidence for nuclear DNA, the ________________ must be present. 4. Shade in the diagram below to show the different parts of a strand of hair. Cuticle – Yellow Cortex - Blue Medulla – Red scales, thickness pigment 5. The cuticle varies in its _____________, its _____________, and whether or not it contains _____________. color 6. The cortex varies in, _______________, texture, and _______________. Thickness 7. The medulla may vary in thickness, _Continuity -___, and ___Opacity_____. species 8. The cuticle and medulla can be important for distinguishing between hairs of different _______________, but often does not lend much important information to the differentiation between hairs from different people. _______________. 9. The structure of hair has been compared to that of a _pencil________ with the medulla being the wood lead ____________, the cortex being the ______________ and the cuticle being the _____paint ____ on the outside. Fiber Evidence fiber 13. A _______________is the smallest unit of a textile material that has a _______________many times greater length diameter than its _______________ . A fiber can be spun with other fibers to form a _____yarn_______that can be woven or knitted to form a fabric. 14. The type _______________and length of fiber used, the type of fabric _______________method, and the type of _______________construction all spinning affect the transfer of fibers and the significance of fiber associations. 15. Matching _______________fibers on the clothing of a victim to fibers on a unique suspect’s clothing can be very helpful to an investigation, whereas the matching of ___ common___fibers such as white cotton or blue denim fibers would be less helpful. cross transfers 16. The discovery of ______________________________and multiple fiber transfers between the suspect's increases clothing and the victim's clothing dramatically _______________the likelihood that these two individuals had physical contact. Natural Fibers natural 17. Many different _______________fibers that come from plants and animals are used in the production of fabric. cotton 18. _______________fibers are the plant fibers most commonly used in textile materials 19. The animal fiber most frequently used in the production of textile materials is _______________, and the wool most common wool fibers originate from sheep. Synthetic Fibers 20. More than half of all fibers used in the production of textile materials are synthetic or _______-________. man-made. 21. Nylon, rayon, and polyester are all examples of _______________fibers. synthetic Hair & Fiber Identification Lab Hair Samples: Think About It … (1) In which samples are we viewing the cuticle? How do they compare? (2) In which samples are we viewing the medulla? How do they compare? (3) What characteristics can be used to identify hair samples? Fiber Samples ...Think About It … (1) Which samples are natural fibers? (2) Which samples are synthetic fibers? (3) What characteristics can be used to identify fiber samples?