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