1 / 11

Forensic Biology by Richard Li

Chapter 2: Sources of DNA Evidence. Forensic Biology by Richard Li. Introduction to Cells. DNA is located in cells which are the building blocks of the human body Two Types of cells: Sex Cells Somatic Cells. Introduction to Cells. Cell membrane Cytoplasm Nucleus.

diata
Download Presentation

Forensic Biology by Richard Li

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 2: Sources of DNA Evidence Forensic Biologyby Richard Li

  2. Introduction to Cells • DNA is located in cells which are the building blocks of the human body • Two Types of cells: • Sex Cells • Somatic Cells Forensic Biology by Richard Li

  3. Introduction to Cells • Cell membrane • Cytoplasm • Nucleus Forensic Biology by Richard Li

  4. Examples of Biological Evidence • Blood • Most common type found at crime scenes • Consists of erythrocytes (red blood cells), leucocytes (white blood cells), and platelets • Nuclear DNA obtained from leucocytes Forensic Biology by Richard Li

  5. Examples of Biological Evidence • Hair • Consists of root and shaft • Medulla • Cortex • Cuticle • Grows at approximately 0.3mm per day • Anagen phase- growing phase • Catagen phase- follicle becomes inactive • Telogen phase- growth cycle ends Forensic Biology by Richard Li

  6. Examples of Biological Evidence • Hair as a source of DNA evidence • PCR allowed more productive analysis of hair • Formerly just analyzed morphology and comparisons • mtDNA can be isolated from roots and shafts • Nuclear DNA analysis or hair is preferred • Plucked hair with roots • Naturally shed hairs contain little nuclear DNA • Most hairs at crime scenes are naturally shed Forensic Biology by Richard Li

  7. Forensic Biology by Richard Li

  8. Examples of Biological Evidence • Bone • Compact vs. Spongy • Osteocytes • Osteoblasts • Osteoclasts Forensic Biology by Richard Li

  9. Examples of Biological Evidence • Bone • Rate of degradation of human remains varies greatly with environmental conditions • Soft tissue is lost • Bones are more stable • Mass Fatalities-identify victims • Sanding- used to reduce potential of comingled remains, adhering inhibitors, and bacterial contamination Forensic Biology by Richard Li

  10. Examples of Biological Evidence • Teeth • Deciduous/Primary teeth vs. Secondary dentition/Permanent dentition • Dentin- Does not contain cells • Pulp Cavity • Root Forensic Biology by Richard Li

  11. Examples of Biological Evidence • Teeth • Identity of a person • Characteristics of teeth • Alignment • Overall structure • X-rays • Bite mark analysis Forensic Biology by Richard Li

More Related