analysis of biological evidence basic serology and intro to blood

Question 1

understanding basic serology

Question 2

antigen

Answer 2

foreign substance capable of reacting with an antibody

Question 3

immunogen

Answer 3

foreign substance capable of eliciting antibody formation when introduced into a host
natural immunogenicity can be glycolipids as in blood groups, A, B, AB, O
glycoproteins as in Rh and Lewis antigens
a;; immunogenicity are antigens, not all antigens are immunogens, however synonymous in FS

Question 4

epitope

Answer 4

molecular structure on an immunogen, usually a small portion, recognized by an antibody

Question 5

multivalen

Answer 5

when an immunogenicity consists of multiple epitopes

Question 6

antibodies

Answer 6

also known as immunoglobulins and are designated with the Ig prefix

Question 7

polyclonal vs monoclonal antibodies

Answer 7

polyclonal antibodies are created when an immunogenicity is introduced into a host animal
a multivalent immunogen is capable of eliciting a mixture of antibodies
the characteristics of a polyclonal antibody may vary if they are produced by different individual host animals of the same species
monoclonal antibodies are created when aspleem cells are harvested from a host animal and inoculated with an immunogen
the antibodies are fused with myeloma cells allowed to proliferate diluted and then screened for the specified antibody
produces a monoclonal antibody that reacts with a single epitope
employed in many serological assays (tests)
limitations - cannot be used in cross-linked networks utilized in precipitation and agglutination assays

Question 8

antigen-antibody binding reactions

Answer 8

serve as the bases of forensic serology
fall into 2 categories
primary binding assays - most sensitive
secondary assays
precipitation based usually used for species ID
agglutination based normally applied to blood group typing

Question 9

primary binding assays

Answer 9

immunochromatographic assays
monoclonal antibody is immobilized onto a membrane
sample is loaded into the sample well where it binds to a dye-labeled antibody to form an antigen-antibody complex
complex diffuses along the membrane until it reaches the test zone, where the immobilized antibody traps the complex and forms an antibody-antigen-antibody sandwich
method is rapid and simple - great screening test
immuno - antigen-antibody
chromatographic - color
assays - test
portable 0 can be used in the field as well
ideal, cheap, relatively specific and portable
limitations
high-dose hood effect leads to false negative
analyze binds to positive antibodies instead of antigen-antibody complex
dye labeled antibody will become saturated and unbound antigen will compete with the antigen-antibody complexes for the antibody immobilized at the test zone

Question 10

RSID PSA card

Answer 10

P30 prostate specific antigen
found in high conc in semen
PSA=P30=semen
quant line is not useful in forensics
3 lines is posotive
two lines is negative

Question 11

secondary binding assays

Answer 11

precipitation based assays
electrophoretic methods
agglutination based assays

Question 12

precipitation based assyas

Answer 12

primarily used for species identification in forensic bio
immunodiffusion, single and doube
Ouchterlony assay
antibody - precipitation line - antigen

Question 13

electrophoretic methods

Answer 13

combines diffusion techniques and electrophoresis to enhance test results

Question 14

agglutination based assays

Answer 14

used for blood group typing and species identification in forensic testing
qualitative indicate the presence or absence of antigens and antibodies

Question 15

what is blood

Answer 15

normal blood volume constitutes about 8% of body weight - 5.6L in 70 kg man (154 lb)
liquid connective tissue consisting of blood cells suspended in plasma
aids in the transportation of nutrients, gases, and wastes throughout the body
carries oxygen from lungs to cells and carbon dioxide away from cells back to lungs
also provides a defense against invading organisms
DNA comes from white blood cells

Question 16

components of blood

Answer 16

red blood cells
white blood cells
platelets
plasma, the fluid portion of the blood

Question 17

blood

Answer 17

serum
fluid portion of the blood obtained after removal of the fibrin clot and blood cells (LEFTOVER FROM CLOT)
plasma is leftover from spun down anti coagulated blood
anticoagulants in spun down blood
Buffy coat in spun down blood
1% of blood volume, consists of WBCs and platelets
hematocrit
packed RBS volume per unit volume of blood

Question 18

blood clot

Answer 18

a gelatinous mass formed by a complex mechanism involving RBCs, fibrinogen, platelets and other clotting factors
liver produces many clotting coagulation factors
serum left behind

Question 19

red blood cells

Answer 19

called erythrocytes
most abundant cell in body
biconcave disk shaped - useful for gas transportation
mature human red blood cells are enucleated, no DNA
contain hemoglobin, peroxidase like activity
responsible for the transportation of oxygen
gives blood its red color
a heme molecule consists of an organic component and an iron atom (Fe2+)

Question 20

white blood cells

Answer 20

called leucocytes
responsible for the immune functions
3 diff types: granulocytes, lymphocytes, monocytes
have nuclei and thus the main source of nDNA from blood
one sometimes more nuclei
normally 4000-11000 WBC/uL of human blood (avg 9000)
10uL whole blood= 240-660 ng DNA (diploid DNA)
granulocytes (polymorphonuclear leukocytes) , multiple nuclei are most numerous
neutrophils (50-70%), basophils, and eosinophils
neutrophils are phagocytic
granulocytes (monomorphonuclear leukocytes)
lymphocytes and monocytes