exam 1 amplified Flashcards
(65 cards)
What is forensic biology?
Application of the natural sciences, molecular biology, genetics, biochemistry, to the investigation of a crime.
What is a forensic biologist?
A scientist that is trained in biological studies. Scientist that tests, evaluates and testifies in a court of law. Other test/evaluate non-human DNA. (Wildlife, endangered species trades, biothreat agents, etc.)
What are the sub-disciplines of forensic biology?
-Forensic Anthropology (Reconstruction, age, race, injury/cause of death)
-Forensic Entomology (insects)
-Forensic Odontology (Dental remains)
-Microbial forensics (biothreat agents/bioterrorism)
What are characteristics of any forensic scientist?
-Objectivity
-Using scientific inquiry
-Infer how evidence came to be
-DOES NOT establish guilt or innocence
-DOES NOT establish an action as legal or illegal
-Forensic biologist is often blinded from the case to avoid any personal subjectivity
-Communication IS IMPORTANT, forensic biologist explains in layman’s terms
What are some important dates/events from the mid-1800s to early 1900s in forensic biology?
-Gregory Mendel: Father of genetics
-Hardy Weinberg: Formulate principle of population genetics
-Kary Mullis: Develops PCR
-PCR amplifies specific regions of DNA
-Human Genome Project: From billions of dollars to a few thousand in cost over 10 years
Why can’t blood type be used to identify a suspect?
Blood types are not discriminatory enough. They can exclude people (e.g., if suspect has A but scene has B). Cheap and quick test for exclusions.
Who developed DNA ‘fingerprints’?
Alec Jeffreys
What is CODIS?
FBI’s STR database with 13 core loci, later expanded to 16 loci kits.
What principle did Edmond Locard develop?
Locard’s Exchange Principle: “Every contact with an object or another person produces an exchange of physical evidence.”
What is an unknown sample in forensic evidence?
A sample of unknown origin relevant to the case, associated with the crime scene.
What is a known sample in forensic evidence?
A sample taken directly from a suspect or victim.
What is the goal of comparing known and unknown samples?
To find a match between the two.
What are examples of probative items?
Glasses, Hat, Belt, Gum, Phone, Cigarettes
What does NIST do?
Sets scientific standards: evidence collection, preservation, storage/transport/identification, extraction of DNA.
How do you collect a wet blood stain?
Use a pipette or swabs (gold standard).
How do you collect a dry blood stain?
Scrape the material or cut the original item where the stain is found.
How should you package meat or tissue evidence?
Avoid Ziplock bags as bacteria will degrade the sample. Use air-tight bags for dry samples, and transport tissue on ice.
What is the chain of custody?
A record of everyone who has had possession of the evidence, including collection details, case assignment, dates, and signatures.
Why is chain of custody important?
Ensures sample integrity and helps backtrack contamination.
How should you package evidence samples?
Items of separate origin should not be packaged together, wear gloves and change them between items, seal evidence with tape, and assign a unique identifier.
What are the types of contamination in evidence samples?
Cross-contamination, contamination by investigator, bacterial contamination, chemical contamination.
Why is physical evidence critical?
It is often more reliable than confessions and eyewitnesses.
What safety precaution should you take with blood samples?
Assume all blood is infected, always wear gloves.
What is the structure of eukaryotic chromosome packaging?
DNA is tightly packaged with histones. Includes centromere, telomeres, origin of replication.
