Final Exam

Serology

the science of body fluid identification and characterization

examination of blood, semen, saliva, and urine through the use of presumptive tests and confirmatory tests

Plasma

the fluid, straw colored, nonliving portion of blood

55% of total volume of blood

90% water

helps regulate body temperature, contains electrolytes, and transports blood cells, products of digestions, and hormones throughout the body

Red Blood Cells/Erythrocytes

responsible for oxygen distribution

class evidence

about 45% of total blood volume

White Blood Cells/Leukocytes

responsible for cleaning the system of foreign invaders

individual evidence

about 0.1% of total blood volume

Platelets/Thrombocytes

responsible for blood clotting

about 0.17% of total blood volume

Serum

the liquid that separates from the blood when a clot is formed

Peroxidase

an enzyme found in blood that acts as a catalyst for the reagent added to the blood and forms a characteristic color

Presumptive Test

a chemical test that uses color change to detect the possible presence of blood

fast reaction

not specific

Kastle-Meyer/Phenolphthalein Test

presumptive test for blood using the phenolphthalein reagent and hydrogen peroxide to yield a bright pink color

cannot rule out other sources/false positives (copper, broccoli, fruit juice)

not human specific

Confirmatory Test

confirms the blood is human

Luminol Test

chemical tests that reveals invisible traces of blood by making it glow blue in the dark

capable of detecting bloodstains diluted up to 300,000 times

detects iron in hemoglobin and won’t affect DNA testing

Ouchterlony Test

confirmatory test for blood that uses antibody reactions to determine if blood is human

Precipitin Test

can reveal whether blood is human

blood is injected into a rabbit, antibodies are formed, the rabbit’s blood is extracted as an antiserum, the antiserum is placed on sample blood, then the sample will react with human proteins is human blood is present

very sensitive and requires only a small amount of blood

ABO Blood Groups

based on having A, B, both, or no antigens of red blood cells

gene is found on chromosome 9

Rh Factor

may be present on red blood cells

positive if present, negative if not

Antigen

a substance that can stimulate the body to make antibodies

certain ones found in the red blood cell’s membrane account for blood type

Antibody

a substance that reacts with an antigen

recognize and attack foreign molecules

protein secreted by B-cells that specifically bind foreign substances

Agglutination

clumping of red blood cells

will result if blood types with different antigens are mixed

Hematest Tablet

presumptive test for blood

reacts with the heme group in blood, causing a blue-green color

Blood Type A

antigen A on the surface of red blood cells

B antibodies in blood plasma

will agglutinate with blood type B

Blood Type B

antigen B on the surface of red blood cells

A antibodies in blood plasma

will agglutinate with blood type A

Blood Type AB

antigens A and B on the surface of red blood cells

no A or B antibodies in blood plasma

will not agglutinate with either type A or type B blood

universal receiver

Blood Type O

neither antigen A nor B antigens on red blood cells

both A and B antibodies in blood plasma

universal donor

Ways Blood Type Can Change

bone marrow transplant

blood transfusion

bacterial infection

Blood Spatter Evidence

a field of forensic investigation that deals with the physical properties of blood and the patterns produced under different conditions because of various forces being applied to the blood

Angle of Impact

angle at which blood strikes a target surface

Bloodstain Transfer

when a bloody object comes into contact with a surface and leaves a patterned blood image on the surface

Backspatter

blood that is directed back toward the source of energy

Cast-Off/Arc

blood that is thrown from an object in motion

Contact Stain

bloodstains caused by contact between a wet blood-bearing surface and a second surface that may of may not have blood on it

Transfer

an image is recognizable and may be identifiable with a particular object

Swipe

wet blood is transferred to a surface that did not have blood on it

Wipe

a non-blood-bearing object moves through a wet bloodstain, altering the appearance of the original stain

Directionality

relates to the direction a drop of blood travels in space from its point of origin

tapered end points in the direction of travel

Terminal Velocity

the greatest speed at which a free-falling drop of blood can accelerate in air

dependent upon the acceleration of gravity and the friction of the air against the blood

approximately 25.1 ft/s

High Velocity Blood Spatter

greater than 25 ft/s

gives a fine mist appearance

collection of small blood droplets

from gunshot, coughing, sneezing, and explosives

Medium Velocity Blood Spatter

5-25 ft/s

from blunt force trauma and cutting/stabbing actions

Low Velocity Blood Spatter

less than 5 ft/s

from blood dropping from a weapon or wound

drops larger than 3 mm in diameter

Round Bloodstain Pattern

blood falls straight down at a 90-degree angle

Elliptical Bloodstain Pattern

blood droplets elongate as the angle decreases from 90 to 0 degrees

Radial Bloodstain Pattern

results from blood pooling in an open wound

Pooling Bloodstain Pattern

blood that is collected in a puddle

Arterial Spurts Bloodstain Pattern

results from a wound to a major artery

Trail

circular drops from an object

Area of Intersection/Convergence

the locations of the blood source determined by drawing lines from the various blood droplets to the point where they intersect

the spot where the blow occurred

more than one indicated the victim was moving

Secretors

blood-type antigens are found in high concentration in bodily fluids such as saliva, semen, vaginal secretions, and gastric juices

about 80% of the population

Enzyme

biological catalyst used in trance amounts to accelerate a biochemical reaction without being consumed or transformed

often globular proteins

do not make anything happen that could not happen on its own

the same one usually works for the forward and reverse reaction

each type recognizes and binds to only certain molecule(s)

Active Site

a pocket on the enzyme with a specific shape for a certain substrate

Induced Fit

the enzyme fits around the substrate when it enters the active site

Amylase

enzyme found in saliva that initiates food digestion by breaking down starch

Mendel’s Principles

inheritance of traits is determined by genes

genes are passed from parents to offspring

alleles can be dominant or recessive

in sexually reproducing organisms, each adult has two copies of each gene, one from each parent

Exceptions to Mendel’s Principles

some alleles are neither dominant nor recessive

many traits are controlled by multiple alleles or multiple genes

Homologous Chromosomes

chromosomes that occur in pair with copies of genes occupying the same positions of each chromosome

Multiple Alleles

there are more than two allele possibilities for a gene

Allele

version of a gene

Genotype

the genetic makeup of an organism

Phenotype

the visible properties of an organism

Erythroblastosis Foetalis

when a Rh- women bears a Rh+ child, some of the child’s red blood cells enter the maternal bloodstream, inducing the formation of anti-Rh antibodies

these antibodies can cross the placental barrier, causing this blood disorder

drug can be injected to inhibit antibody production

Enzyme Linked Immunosorbent Assay (ELISA)

sensitive, plate-based laboratory technique used to detect and quantify antibodies and antigens

Polyclonal Antibodies

heterogeneous mixtures of antibodies secreted by different B cell lineages

Monoclonal Antibodies

identical immune proteins designed to bind a specific antigen

Direct Immunodetection ELISA

primary antibody conjugated with enzyme system

Indirect Immunodetection ELISA

secondary antibody conjugated with enzyme system

Sandwich Indirect Immunodetection ELISA

antigen applied in soluble forms and secondary antibody conjugated with enzyme system

Indirect Immunodetection With Biotin Linkers

biotinylated primary antibodies

Blocking

reduces non-specific binding

Toxicology

study of poisons/toxins

deals with samples from the body

Occupational Toxicology

deals with chemical hazards in the workplace

Seized Drug Analyst

source is from outside the body

Opiates

depressants that cause euphoria and analgesia and are derived from morphine

causes death by paralysis of the respiratory center

Amphetamines

stimulants that cause intense euphoria

have controlled purchase limits

Cocaine

stimulant produced by the coca leaf

Cannabinoids

psychoactive compounds that cause euphoria, perceptive alterations, and memory impairment

Polypharmacy

lethal combination of drugs

Alcohols

enter the membranes of nerve cells, disrupting normal signaling

Cyanide

binds to ferric ions in cytochrome oxidase, interrupting electron transport and energy generation

antidotes are ineffective due to rapid action

Carbon Monoxide

causes more deaths than any other toxin

binds to hemoglobin and prevents it from transporting oxygen to tissues

DNA Profiling

a technique used by scientists to distinguish between individuals of the same species using only samples of their DNA

Restriction Enzymes

enzymes that cut DNA at specific base sequences by cutting phosphodiester bonds

Restriction Fragments

the sections of DNA cut by restriction enzymes

Gel Electrophoresis

separates DNA on the basis of size

DNA fragments are injected into wells, and an electric current is applied

negatively charged DNA is attracted to the positive end

shorter DNA fragments move faster

Genetic Fingerprint

the pattern of bands in a gel electrophoresis

Single Nucleotide Polymorphisms (SNPs)

DNA differs by one nucleotide

Simple Sequence Repeats (SSRs)/Short Tandem Repeats (STRs)

sequences that repeat a variable number of times in different individuals

commonly used in DNA profiling

Band

a well-defined line of DNA on a gel

contains many DNA fragments of the same size that have all traveled as a group to the same position

Polymerase Chain Reaction (PCR)

a technique to make many copies of a specific DNA region in a test tube

relies on thermostable Taq polymerase

reaction is repeatedly cycled though a series of temperature changes, allowing many copies of the region to be produced

Primer

a short sequence of nucleotides that provides a starting point for DNA synthesis

Taq Polymerase

thermostable enzyme for copying DNA from the heat tolerant bacterium Thermus aquaticus

used in PCR

Denaturation

first stage of PCR

the reaction is heated to separate DNA strands, providing single-stranded templates

temperature must be igh enough to overcome attrctive energy of hydrogen bonds between bases

Annealing

second stage of PCR

reaction is cooled so the primers can bind to their complementary sequences on the single-stranded template DNA

temperature depends on length of primer, number of Gs and Cs, and salt concentration

Extension

third stage of PCR

reaction temperature is raised so Taq polymerase extends the primers, synthesizing new strands of DNA

temperature is optimal temperature for enzyme

the longer the expected product, the longer the time required

dNTPs

the essential building blocks used by DNA polymerase to synthesize new strands of DNA during PCR

must be present in sufficient excess to complete extension through all cycles

PCR Buffer

solutions that contribute to correct folding of and optimal activity of enzyme

Tm in PCR

temperature at which 50% of the possible primer/template complexes are unformed

Thermocycler

instrument programmed to change samples rapidly from one set temperature to another

Primer Dimers

small, unintended PCR products formed when primers anneal to themselves or each other

visible below 100 bp maker on gel

can be caused by great primer excess, 3’ end of primers being complementary, insufficient target template, too many cycles, annealing temperature too low, and insufficiently specific primers

Misincorporation

an error where DNA polymerase inserts an incorrect, non-complementary nucleotide during amplification, causing mutations in the final product

can be caused by great excess of dNTPs, dNTPs present in unequal concentrations, polymerase lacking editing activity, polymerase concentration too high, extension temperature too low, or magnesium concentration too high