erythrocytes
red blood cells; carry O2 throughout body, dispose CO2, contain hemoglobin
hemoglobin
allows RBC to carry O2, contain iron
leukocytes
white blood cells; immune system, defend against infection / viruses
thrombocytes
platelets; cell fragments that cluster around wounds to stop bleeding
plasma
the liquid component of blood; carries cells, hormones, nutrients, proteins, electrolytes, etc. throughout the body
presumptive test
a screening test that indicates the possible PRESENCE of a material of interest (not specific identification)
What are the presumptive tests for the presence of blood?
based on the properties of hemoglobin (iron binds to oxygen): leucocrystal violet, luminol, KASTLE-MEYER
leucocrystal violet (LCV)
a presumptive blood test that turns blood violet, used on porous surfaces (e.g. carpet blood stains)
luminol
a presumptive blood test that turns blood glowing blue, reacts with many other substances other than blood so ehhh on trustworthiness
Kastle-Meyer
the most common presumptive blood test; phenolphthalein reacts with the iron in hemoglobin
confirmatory test
a test that is SPECIFIC for the presence of a body fluid, stain, or residue of interest, and reduces or eliminates false positive results
What is the confirmatory test for blood?
relying on antigens and agglutination
What occurs when an antibody locks onto its corresponding antigens?
agglutination
antigens
structures on the surface of red blood cells
antibodies
latch onto and attack corresponding antigens, causing agglutination
Type A Blood
A antigens, B antibodies (Anti-B)
Type B
B antigens, A antibodies (Anti-A)
Type AB
BOTH A and B antigens, NO antibodies
Type O
no antigens, BOTH A and B antibodies (Anti-A and Anti-B)
What blood type is the universal receiver?
AB+ (no antibodies for A, B, or Rh or it would attack itself!)
What blood type is the universal donor?
O- (no antigens means nothing for the antibodies to latch onto)
Rhesus (Rh)
the antigen that makes a blood type positive in its presence (no Rh means a negative blood type)
Which blood type has Rh antibodies?
negative
What is transferred in blood transfusions?
blood cells (plasma with antibodies are removed, so cannot attack the receiver's blood)
blood spatter analysis
provides point of origin for blood
point of origin
location of a blood source
transfer blood spatter
when a blood source comes into contact with a surface (e.g. smears, smudges, trails)
spatter blood spatter
when a source of liquid blood travels through the air, landing on a target surface and splattering outwards
falling droplets blood spatter
droplets dropped DIRECTLY from above at a 90 degree angle (e.g. circular stains)
force and direction blood spatter
struck the surface at an angle, with an external force propelling at horizontal velocity; tail indicates direction
radial blood spatter
impact causes droplets to fly away at high speeds
height determination graph
uses standard curve to show mathematical relationship between two quantities
What can DNA be extracted from?
white blood cells, bones, hair follicles, preserved body parts, clothing and fiber, bodily fluids
Why can't RBC be used to extract DNA?
RBC lose their nucleus when they mature, so no DNA
Polymerase Chain Reaction (PCR)
process of copying DNA by adding a target sequence, deoxyribonucleotides, Taq polymerase enzyme, buffer, and DNA primers to a PCR tube all in a thermal cycler
thermal cycler
lowers and raises temperatures
denaturation in PCR
HEAT UP; separates complementary DNA strands
annealing in PCR
COOL DOWN, DNA primers attach to each end of the target sequence
extension in PCR
HEAT UP, Taq polymerase adds complimentary bases (deoxyribonucleotides) to build new strands
How many times can PCR repeat?
30-40 times in an hour
restriction enzymes/endonucleases
cut DNA in specific places called recognition sites in the process of restriction dig
How are recognition sites symbolized?
^
Where are restriction enzymes sourced from?
bacteria who use it to defend against viral DNA
How are restriction enzymes named?
bacterial source, strain / genetic variant, and order of discovery (e.g. Escherichia coli from the RY13 Strain discovered first --> EcoRI)
blunt ends
created by restriction enzymes that cut straight down the middle
sticky ends
created by restriction enzymes that cut jaggedly (diagonally)
gel electrophoresis
the process of separating and comparing DNA pieces, uses agarose gel and buffer
agarose gel
made from agar (from seaweed), porous
What pieces of DNA in gel electrophoresis travel farthest?
smaller pieces can move through the pores more easily, so travel farther
What distance do DNA pieces that are the same size travel?
at the same rate, landing in the same place
buffer
a chemical solution that conducts the electric current in gel electrophoresis
loading a gel
the process of adding DNA before running gel electrophoresis
well
indentations in the gel, made using a comb while the gel is setting
lane
the area the DNA travels down
loading dye
mixture of dye (e.g. blue) and sugar (e.g. glycerol)
What is dye used for in gel electrophoresis?
to visually track DNA's migration through the gel (run ahead since they are smaller than DNA)
What is the sugar used for in gel electrophoresis?
heavier than DNA, so binds to it and sinks it to the bottom of wells (prevents from floating away in the buffer)
What side of the electrophoresis chamber is the DNA placed in?
the negative side; DNA is negatively charged so will move to the positive side
DNA ladder/marker
the standard for comparison for DNA base pair (bp) measures, made of known DNA fragment sizes
restriction fragment length polymorphism (RFLP)
the different patterns of DNA fragments resulting in variation in DNA sequences recognized by restriction enzymes, "unique DNA fingerprint"
micropipettes
transfer microvolumes of liquid
CODIS
U.S. national DNA database with DNA of convicted criminals, unidentified human remains, missing persons and their relatives, and crime scene DNA samples