CHE 113 Final Exam review
What type of blood cell is involved in transporting hemoglobin to cells?
Erythrocytes
Quantatitative analysis focuses primarily on
How much of a substance is present in a sample
Matching key features found in an unknown sample with candidates from a very large pool of known possibilities is commonly referred to as
one-to-many matching
Can hairs from the same head have different morphological characterisitics?
Yes
How DNA works
- Nuclein acid carries genetic information (DNA & RNA) -Consists of a phosphoric acid molecule, five carbon sugr, nitrogen containing base
Electron Microscope
-A beam of electrons, instead of light, is used with an electron microscope -Magnify greater because wavelengths of electrons are much smaller than those of visible light
Visualizing prints for hard surfaces
-Aluminum dust: highly visible on dark and mirrored surfaces -Carbon black for white surfaces -Luminescent powders: fluoresce under ultraviolet light -Magnetic powder
Gel Electrophoresis
-Amplify DNA sample, react with restriction enzymes, prepare sample -Use elec. Current to move DNA pieces -Seperates DNA by fragment size -Smaller pieces travel the fastest
Can estimate time of death from?
-Body temp changes -Rigor mortis -Insect action -Stomach contents -Last known activity -Normal postmortem changes
DNA Analysis
-Collection of Sample -Separation and Purification of DNA -Amplification -Cutting/Separation of Fragments -Comparison and Analysis
Projected bloodstains
-Created when a blood source is subjected to an action greater than the force of gravity
Tandem Repeats
-DNA forms genes that code for proteins -Not all DNA codes for proteins -Intergene regions contain many A, T, C, G repeats called Tandem Repeats -Forensic DNA typing uses tandem repeats
Comparison Microscope
-Important tool for firearms examiner -Two compounf miscroscopes combined into one unit -When viewer looks through the eyepiece, a field divided into two equala parts is observed
Problems with Frye Standard
-Inflexible (and slow) for new developments or extensions of existing techniques and methods -Requires complete agreement in the scientific world
DNA Structure
-Info in the order of nucleotides in DNA can be transcribed and translated to direct the preparation of proteins in the cell -Every three nucleotides in DNA codes for one amino acid in the formation of a protein -Parts of DNA coding for proteins are called genes -DNA contains vert large parts that code for nothing known
Types of prints
-Latent prints: invisible to the naked eye and must be developed to see -Visible prints -Plastic prints: impression of fingerprints in soft media
Polarizing Microscope
-Light confined to a signle plane of oscillation is said to be polarized -Reduced glare by transmitting light in a vertical plane only
Hair: Class evidence
-Resistant to chemical decomposition and long-term structural stability -Can determine the sex of the owner -Can occasionally determine race
RFLPs
-Restriction enzymes are used to RFLPs in the DNA helix -All humans have the same type of repeats -Typically, the restriction enzyme cuts DNA at very specific placed -Gel electrophoresis is used to sort the different lengths of DNA fragments
Uniqueness of RBCs
-Shape: biconcave disc, round and flat -No nucleas -Can change shape -Contains hemoglobin
Darkfield Microscopy
-Shows a light silhouette of an organism againsts a dark background. The light reaches the specimen from an angle with the help of an opaque disk -The specimen then appears lit up: against the dark background -Useful for very small living organisms
Blood falling from a wound only under the influence of gravity is referred to as a
Passive bloodstain
What does the LD50 of a substance refer to?
The amount of substance necessary to kill off half of the population
Fluorescence Miscroscopes
-Specimens are first stained woth fluorochromes and then viewed through a compounf microscope by using an ultraviolet light source -Used primarily in a diagnostic procedures called flourescent-antibody technique
Phase Contrast Microscope
-Splits a beam of light into 2 types of light, a direct and refracted and brings them together to form an image of the specimen -Allows detailed observations of internal structures.
Compound Light Microscope
-The most commo microscope -Two sets of lenses: ocular and objective -Optical system comprised of condenser, objective lens, eyepiece lens and illuminator
Transmission Elec. Microscope (TEM)
-Thin sections can be seen in transmission electron micrograph -Electrons pass directly through the specimen
Scanning Elec. Microscope
-Views of the surfaces by aiming a beam of electrons onto the specimen
Six critcal questions "posed" by a pathologists
-Who are you? -When did you become ill/hurt/die -Where did you get hurt/die -Did you die as a result of violence, natural causes or combo -Was it suicide, accidental, homicide, undetermined -Who killed you
White blood cells
-a part of the immune system and fights infection -circulate in the blood to be transported to an infection sight -when the number of WBCs in your blood increases it is a sign of an infection
Visualizing fingerprints for porous surfaces
-iodine fuming -ninhydrin -superglue fuming
Red Blood Cells
-most abundant cells in the blood -RBCs ac% of the blood -The % of blood made up of RBCs is frequently measured and is called the hematocrit. -The ratio of cells in normal blood is 600 RBCs for each white blood cell and 40 platelets
Blood chemistry
1. Blood rich in CO2 - pumped from the heart into the lungs through the pulmonart arteries 2. CO2 in the blood is exchanged for O2 in the lungs 3. Oxygen-rich blood - back to the heart through pulmonary veins 4. Oxygen-rich blood - pumped from the heart to the body through arteries 5. In the tissues, the arteries narrow to tiny capillaries where O2 int he blood is exchanged for CO2 6. The capilaries widen into the veins which carry CO2 blood back to the heart
What is true about forensic science?
1. Evidence provides info that can and should influence the beliefs of an observer aout a specific legal quesiton 2. Evidence must be relevant 3. Experts must employ the same level of intellectual rigor as experts in the relevant field
Autopsy
1. External examination 2. Internal examination 3. Removal of the brain 4. Weighting the Organs 5. Examination of the Stomach and GI Tract 6. Sample Collect 7. Return Organs to Body
Biome
A large community of plants and animals that occupy a habitat in the natural world
What is PCR
A technique that can produce many exact copies of segments of DNA
A protein is a biopolymer built by deocding the DNA and is composed of many ___ units connected in a chain
Amino acid
Hair growth phases
Anagen - initial phase where hair actively grows (up to 6 years) Catagen - transition between active and loss stage, slowed growth (up to several weeks) Telogen - final phase resulting in hair loss (up to 6 months)
Time of Death
Antemortem: prior to death Perimortem: about the time of death Postmortem: After death Postmortem interval: The time between the actual death and finding the body
What is the "Fruit of the Poisonus Tree Doctrine"?
Any evidence found through a illegal search also cannot be used to find other evidence
Blood in the arteries vs. Blood in the veins
Arteries: is oxygen-rich (from lungs) Veins: is oxygen-poor
Fly development
At warmer temps the rate of development is fast, at cool temps it slows down
The light given of by fireworks is an example of what?
Atomic emission
The Decay Stage of decompisition
Begins when the abdominal wall breaks, gasses escape and the carcass deflates
Back spatter
Blood directed back towards the source of energy or force that caused the spatter
The chief function of the liver system
Blood purification
Forward spatter
Blood which travels in the same direction as the source of energy or force which caused the spatter.
Morphology of Hair
Cuticle - scales on exterior of hair shaft Cortex - main body of shaft Medulla - either absent or contains 1/3 diameter of the shaft
How does burial impact the decay process
Burial can slow the decay process
Chemical formula of ethonal (the "alcohol" in alcoholic beverages)
CH3CH2OH
What is the document that certifies that a piece of evidence has been handled properly from discovery to analysis to allow admission into court?
Chain of custody form
Secondary explosives
Compounds that are relatively stable to heat, shock, eletrical discharge, and friction and usually require much more energy to detonate
Primary explosives
Compounds that are sensitive to heat, flame, shock or friction and typically detonate quickly.
AFIS
Computerized system for storing and retrieving finderprint records
The main advantage and difference of the Daubert Standard over the Frye Standard is that
Daubert allows new types of scientific evidence to be used in court faster
Post Decay Stage
Day 10-25 In dry habitats, remains are skin cartilage, and bones. In wet habitats, wet material in the soil under the remains -Large maggots are leaving or have left
Dry Stage
Day 25+ Mainly bones and hair remain. Odor is primarily that of normal soil and litter. Can last several months to years -Beetles move in and other insects with the ability to digest keratin
Fresh Stage
Days 1-2 Commencing at death, ends when bloating is first evident. Breakdown of protein and carbohydrates into simpler compounds -Blowflies detect cadavar and lay eggs
Bloated Stage
Days 2-6 Putrefaction begins. Gasses produced by anaerobic bacteria inflate the adbomen -Flesh flies appear; small maggots are feeding
Under what circumstances can illegally obtained evidence generally be used in court?
During post-trial sentencing
The process of spectroscopy in which an electron moved from a higher energt state to a lower energy state
Emission
With regard to skeletized human remains, which of the following may be used to estimate the age of an individual at the time of his/her death?
Epiphyseal Union
Hemoglobin
Hemoglobin is a protein containing heme group.
A precipitin test is used primarily to identify
If the blood found is human
The police are not required to obtain a search warrant if they are
In the process of a legal arrest
Evidence that can be associated with a particular source with an extremely high degree of probability is said to possess
Individual characteristics
Transfer bloodstain
Is created when a wet, bloody surface comes in contact with another surface
Atoms of a given element with different numbers of neutrons but the same number of protons
Isotopes
How did the Frye decision of 1923 impact the admissibility of forensic evidence?
It established the minimum standards for admissibility of scientific evidence
Hair can most often be characterized as originating from an animaly by examining
Its cuticle (scale) structure
Where in the body is most of ingested alcohol completely oxidized?
Liver
The process by which the blood in a body settles to the lowest point after death
Livor mortis
In mass spectrometry, moleculels with charges (ions) are deflected accordig to their mass by a what?
Magnetic field
A channel in the center of the hair shaft is known as the
Medulla
Cyanide is classified in toxicology as a what?
Metabolic poison
Rigor Mortis
Muscle fibers become cross linked, muscles stiffen. First noticed 2-4 hr pm. Remains 12-24 hrs.
Where are the chromosomes located in the body?
Nucleus
The fluid portion of blood as it is removed from someone that accounts for approximately 55% of blood is known as the
Plasma
What is the frequency of occurance of an event
Probability
What structure of the pelvis can determine the gender if its owner?
Pubic arch
In the case of Mincy v. Arizona, with respect to the collection of evidence, the main importance was
Sets limits on the collection of evidence as to the reasonable extent and duration of an emergency
Proxy indicators
Small amounts of identifiable material from an ecosystem that can indicate with relatively high accuracy
Satelitte Spatter
Small droplets of blood that are distruted around a drop or pool of blood as a result of the blood impacting the target surface
What is an example of identification analysis?
Spectrophotometric determination that a sample is cocaine
What microscope has the ability to examine larger objects in 3D readily?
Stereoscopic
Angle of impact
The acute angle formed between the direction of a blood drop and the plane of the surface that it strikes
Algor Mortis
The change in body temperature
In gas chromatography using a long glass tue to separate components of a complex mixture, which of the following is the stationary phase?
The glass tube
Locard's Exchange Principle
The most basic concept of Forensic Science: -Criminal in contact with an object or person, a cross transfer of evidence occurs -Examples;dust, biological samples, fingerprints, chemical residues
Forensic taphonomy
The movement of the body after death
PMI
The time interval since death
What is the best definition of forensic science?
The use of scientific methods to help answer legal problems
As the angle of impact decreases
The width of the blood stain increases and vice versa
Nucleic Acids
Three "building blocks" linked through condensation reactions to form polymers
Blood type
Type A: Only the A protein is present/ B antibody is present Type B: Only the B protein is present/ A antiody is present Type AB: Both proteins are present/ Neither A nor B antobies present Type O: Neither protein is present/Both A and B antobodies are present
The Principle of Individuality means that
Two objects may be indistiguishable but they are never identical
Luminol Test
Used for Blood ID -Very sensitive -Detects unseen samples and patterns -Does not interfere with later DNA testing
Immunoassy
a technique utilizing antibodies to bind specifically to targeted substances in a specimen in order to identify their presence
Osteology
study of skeletal remains -Human bones vs. animal bones -Macroscopic differences -Radiology -measurement -Miscroscopic differences