What is blood?
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The fluid that circulates in the principal vascular system of human beings and other vertebrates.
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What is blood?
The fluid that circulates in the principal vascular system of human beings and other vertebrates.
What can different components of blood be used for?
Different forensic assays.
How many forms of blood can be used for analysis?
Two forms.
What is the population percentage of blood type A?
42%.
What is the first biomedical question investigators ask regarding blood?
Is it blood?
What is the second biomedical question investigators ask about blood?
Is it human blood?
What is applied to the gel medium in precipitin tests?
An electrical potential.
What is the population percentage of blood type B?
12%.
What is the third biomedical question investigators ask regarding blood?
Whose blood is it?
What is a key requirement for blood testing in precipitin tests?
Only a small amount of blood is required.
What is the population percentage of blood type AB?
3%.
What can mixing two different blood types lead to?
Blood agglutination.
What does forensic serology involve?
The examination and analysis of body fluids.
What can trigger a false positive in the Luminol test?
Other ions such as copper.
What does PSA stand for?
Prostate-Specific Antigen.
What type of bloodstains can precipitin tests be used on?
Dried and old bloodstains.
What is the population percentage of blood type O?
43%.
Why is blood commonly found in crime scenes?
Because it is often present during violent crimes.
What are the two methods for ABO blood typing?
(i) ABO typing (ii) Reverse typing.
What are the major types of serological evidence?
Blood and body fluids generated by sexual assault cases, including semen, saliva, and vaginal secretions.
What is the role of blood typing in paternity testing?
It can help to exclude paternity but cannot absolutely verify it.
What does RSID™ stand for in the context of saliva testing?
RSID™ is an immunochromatographic strip test.
Which enzyme can catalyze the oxidation of luminol?
Horseradish peroxidase.
What type of test is the PSA Semiquant?
An immunochromatographic rapid test.
What are the two main categories of how blood can leave the body?
What is one importance of blood typing in investigations?
It helps narrow down investigations.
What can bloodstains indicate about a crime?
They can provide clues about the locations of the victim and suspect during the crime.
What is the purpose of blood group determination?
To identify blood types and prevent agglutination.
What is the ultimate goal of forensic serology?
To determine who the blood or body fluids came from.
What is a Punnett square?
A diagram used to predict the outcome of a particular cross or breeding experiment.
What does a color change within 1 minute indicate in preliminary tests for blood?
It indicates a positive reaction.
What is the purpose of incident reconstruction in forensic analysis?
To determine what happened during a crime.
What type of molecules are found on the surface of human red blood cells?
Glyco-sphingolipids.
What is the main target of the RSID™ saliva test?
Human salivary α-amylase.
What is the purpose of the PSA Semiquant test?
To detect PSA levels.
What environmental condition can lead to false positives in the Luminol test?
Enclosed spaces with excessive smoke.
What causes passive bleeding?
The action of gravity.
What information can blood reveal in forensic analysis?
The presence of disease, drugs, and alcohol.
How is blood typing used in paternity testing?
It helps determine biological relationships.
What can produce a false positive result in blood tests?
Some vegetable materials such as potatoes and horseradish.
What are the possible genotypes for a child with blood group A?
AA and AO.
What are the advantages of preliminary/presumptive tests for blood?
They are cheap, quick, reasonably sensitive, and convenient to use.
Who developed the Teichmann test?
Ludwik Teichmann in 1853.
What is a new feature mentioned for the PSA test?
New cassette.
What type of antibodies does the RSID™ saliva test use?
Dual monoclonal antibodies.
What is coagulated blood?
A mass of blood that has clotted, formed by the stimulation of fibrin.
What information can bloodstain pattern analysis (BPA) reveal?
The origin of the blood stains, number of attacks, truthfulness of suspects and witnesses, type of instrument used, direction of impact, relative positions of individuals, and movements during the attack.
What are glyco-sphingolipids composed of?
A hybrid molecule of carbohydrate and lipid.
What do Hemastix strips detect?
The peroxidase-like activity of hemoglobin.
What is meant by blood being projected from the body?
Blood leaves the body due to a person or object applying some force other than gravity.
What are polymorphic enzymes in human blood?
Enzymes that exist in several forms, such as Phosphoglucomutase (PGM).
How can blood be used to identify individuals in forensic cases?
Through DNA analysis.
What does LMG stand for in forensic testing?
Leuco malachite green.
What happens to blood cells when mixed with Anti-A serum?
They clump together if the sample is type A.
What does a positive result in blood tests indicate?
Not a positive proof of blood.
What is the phenotype for a child with genotypes AA or AO?
Blood group A.
What is a disadvantage of preliminary tests for blood?
They can only indicate a likelihood that blood is present.
What is a limitation of the Teichmann test?
It can't determine the species from which the blood originated.
What is saliva considered in forensic analysis?
One of the vital fluids secreted in human beings.
What is the purpose of microscopic identification in forensic analysis?
It serves as a confirmatory test for visual identification of sperm cells.
How can BPA help in understanding the crime scene?
By revealing the locations and movements of the victim and attackers during the attack.
Which carbohydrate molecule is mentioned in relation to glyco-sphingolipids?
N-acetyl galactosamine.
What is a key characteristic of the RSID™ saliva test?
High specificity.
What does serum contain?
Water, antibodies, proteins, salts, and many other components.
What is the primary use of Hemastix strips?
To detect blood in urine.
What is a key aspect of bloodstain pattern analysis (BPA) at a crime scene?
Analyzing vertical drips and flow patterns.
In which bodily fluids does Phosphoglucomutase (PGM) exist in significant concentrations?
In blood and semen.
What is the chemical formula for Leuco malachite green?
C23H26N2·H2O2.
What is the primary test used to detect starch?
Starch - Iodine test.
What indicates a blood sample is type B?
Clumping occurs when mixed with Anti-B serum.
What is the purpose of using a Phadebas tablet in testing?
To measure amylase activity.
What percentage of total blood is plasma?
55%.
What can a negative result in blood tests conclude?
The absence of detectable quantities of heme.
What can interfere with preliminary blood tests?
Many other materials, including both oxidizing and reducing agents.
How sensitive is the Teichmann test compared to color tests?
It is less sensitive than color tests such as the luminol test.
What is an example of a stain used in microscopic identification?
Christmas Tree stain.
Why is saliva important for individual identification?
It is an important source of DNA.
What is the location of the ABO gene locus?
9q34.
What does BPA stand for?
Bloodstain Pattern Analysis.
What is another carbohydrate molecule associated with glyco-sphingolipids?
Galactose.
How is serum separated from blood?
By allowing blood to clot and then separating the liquid that forms.
What does 'negative' typically refer to in a general context?
A state or condition that is undesirable or unfavorable.
How do you use Hemastix strips?
Moist the strip with DI water and place it in contact with the bloodstain.
What reaction does Phosphoglucomutase (PGM) catalyze?
The reversible conversion of glucose 1-phosphate to glucose 6-phosphate.
What happens to blood cells when mixed with incompatible blood types?
They clump together.
What is the purpose of the Microcrystal Test?
To confirm the presence of blood.
What happens when antibodies and antigens diffuse toward one another on an agar-coated plate?
A line of precipitation forms where they meet if the blood is from a human.
What color does the LMG test produce?
Colorless to blue-green.
Where is α-amylase found in higher concentrations?
In saliva, 50 times higher than in other body fluids.
What is the composition of blood platelets and white blood cells in total blood?
Less than 1%.
At what wavelength is the glucose measured in the Phadebas test?
620 nm.
What does clumping with both Anti-A and Anti-B serums indicate?
The sample is type AB.
What is the sensitivity level of the Luminol test?
It can detect bloodstains diluted to as little as 1 in 100,000.
What can cause a false negative result in blood tests?
The presence of a reducing agent that interferes with the oxidation reaction of the tests.
What color represents the anterior part of sperm when stained with Christmas Tree stain?
Pink.
What types of bloodstains can the Teichmann test be used on?
Dried and old bloodstains (over 20 years old).
Why is bloodstain pattern analysis considered important?
It provides critical insights into the dynamics of a crime scene.
What are the three main allelic forms of the ABO gene?
A, B, and O.
From where can saliva be recovered?
From stamps, food, and bite marks.
What is a limitation of preliminary blood tests regarding species?
They cannot differentiate between species.
What does 'positive' typically refer to in a general context?
A state or condition that is desirable or favorable.
How many major phenotypes of PGM are there?
Three major phenotypes.
What type of blood is collected without an anti-coagulant?
Coagulated blood.
What chemical is contained in Hemastix strips that indicates blood?
TMB (C16H20N2).
What are the three main allelic forms of blood type?
A, B, and O.
What indicates that a sample is type B when mixed with type A blood?
Clumping occurs.
What is the first antibody used in the PSA detection process?
1st mouse Anti-human PSA antibody (gold-labelled; mobile).
What is the Kastle-Meyer (KM) color test used for?
To detect the presence of blood.
What is an example of a Microcrystal Test?
Takayama test.
What is used as a control in the immunodiffusion assay?
Human blood.
What is a limitation of the amylase activity-based tests?
They are not specific to humans.
What percentage of total blood do red blood cells constitute?
45%.
What is the basis of the LMG test?
The peroxidase-like activity of hemoglobin.
What color does the starch-iodine complex turn when iodine is present?
Dark blue/black.
What does it mean if there is no clumping with either serum?
The sample is type O.
What does PSA stand for in the context of confirmatory tests?
Prostate Specific Antigen.
What color represents the posterior part of sperm when stained with Christmas Tree stain?
Dark red.
What is Phadebas?
A synthetic biochemical substrate consisting of starch polymers with a blue dye covalently bonded.
What are two limitations of preliminary tests for blood?
Sensitivity and not being definite proof.
What is the minimum amount of blood that can be detected using the Teichmann test?
Down to 1 μl of blood or 0.1 mg of hemoglobin.
How is the Luminol reagent applied during testing?
It is sprayed onto a suspect item.
What activity is tested to determine the presence of saliva?
α-amylase activity.
What technique is used to analyze PGM patterns?
Electrophoresis.
How can 'negative' be perceived in emotional contexts?
As feelings of sadness, anger, or pessimism.
What controls the A - B - O genotype?
Multiple alleles.
What is the role of the second antibody in the PSA detection process?
2nd mouse Anti-human PSA antibody (membrane fixed).
What indicates that a sample is type A when mixed with type B blood?
Clumping occurs.
What does the A allele encode?
1-3-N-acetylgalactosamine transferase.
What methods can be used to settle blood?
By gravity or centrifugation.
What color change indicates the presence of blood when using Hemastix strips?
Colorless to green.
What enzyme digests starch into smaller carbohydrate units?
Amylase.
What property of blood hemoglobin is utilized in the KM color test?
It possesses peroxidase-like activity.
What are Takayama crystals?
Crystals formed during the Takayama test that indicate the presence of blood.
What is the purpose of the precipitin ring test?
To identify the species of blood.
What reagents are required for the immunodiffusion assay?
Antiserum against human blood and an agar-coated plate with wells.
What is the sensitivity range of the LMG test?
1 in 5,000 to 10,000.
What is the stability duration for detecting α-amylase activity?
Up to 28 months.
Where is amylase found in the human body?
In both saliva and the pancreas.
What is un-coagulated blood?
The fluid portion of un-clotted blood.
What type of blood sample is used for ABO typing?
Uncoagulated blood.
Why is the determination of vaginal secretions important?
It is crucial in cases involving sexual assault.
What is the main source of PSA?
It is mainly found in semen, secreted by the prostate gland.
What color represents the neck and tail of sperm when stained with Christmas Tree stain?
Green.
What are the two formats of the Phadebas test?
Starch - Blue dye and Amylase - Blue dye.
What role does iron in hemoglobin play in the Luminol test?
It acts as a catalyst in the reaction.
How can 'positive' be perceived in emotional contexts?
As feelings of happiness, optimism, or enthusiasm.
What does a positive result indicate in the PSA test?
Presence of PSA in the sample.
What is an allele?
Alternative forms of a gene located at the same point on a particular pair of chromosomes.
What test is used to visualize starch digestion?
Radial Gel Diffusion Starch Iodine test.
What does it mean if there is no clumping when mixing blood?
The sample is type AB.
What is the sensitivity of the KM color test?
1 in 10,000.
What bond does the A allele form?
Bonds N-acetylgalactosamine to D-galactose.
Why are preliminary tests for blood not sufficient?
They are not specific and can give false positive results.
What types of antiserums are commercially available for species identification?
Antiserums against different animals such as dog and cat.
What type of antiserum is used in the immunodiffusion assay?
Rabbit antiserum against human blood.
What is formed when amylose interacts with iodine?
A dark blue/black color due to the formation of helices.
What is mixed with blood samples for ABO typing?
Serums containing antibodies for Type A and B blood.
What is the main component of plasma?
Mainly water.
What does the blue dye in the Phadebas test indicate?
It is released at a rate proportional to the quantity of the enzyme present.
What type of cells are detected in vaginal secretions?
Glycogen-rich epithelial cells.
What is the concentration range of PSA in semen?
0.2 - 3 mg/ml.
What are some limitations of microscopic identification?
Old samples and vasectomized males.
What does the Phadebas amylase test indicate?
The presence of amylase, indicated by a blue color change.
What chemical reaction occurs in the Luminol test?
H2O2 + luminol produces a strong glow.
In terms of feedback, what does 'negative feedback' imply?
Criticism or suggestions for improvement.
What does a negative result indicate in the PSA test?
No PSA in the sample.
What is a dominant allele?
An allele that produces the same phenotype whether paired with an identical or different allele (e.g., A, B over O).
What type of serum is mixed with known type A and B blood to determine type O?
A serum sample containing antibodies.
What color indicates the presence of starch in the Starch Iodine test?
Blue.
What type of test is the KM color test considered?
A preliminary/presumptive test for blood.
What is the result of the starch-iodine test when amylase is present?
Yellow/brown color indicating glucose and free iodine.
How can human blood be identified using the precipitin ring test?
By using rabbit antibodies against human blood antigens.
What does the B allele encode?
1-3-galactosyltransferase.
When was the Takayama test developed?
In 1912 by Takayama L.
What substances does plasma contain?
Proteins, antibodies, hormones, vitamins, and salts.
Which reagent is used to stain glycogen in vaginal secretions?
Periodic acid-Schiff (PAS) reagent.
How does the concentration of PSA in vaginal fluid compare to that in semen?
In vaginal fluid, it is much lower, at 0 - 1.25 ng/ml.
What is the result of the Phadebas test when glucose is produced?
Colorless solution.
What types of bloodstains can the Luminol test detect?
Blood stains that have been washed out, wiped off, or are invisible to the naked eye.
In terms of feedback, what does 'positive feedback' imply?
Praise or reinforcement of good performance.
What principle is used in the PSA detection method?
Semiquantitative principle.
What is a recessive allele?
An allele that produces its characteristic phenotype only when paired with an identical allele (e.g., O).
What is the purpose of mixing serum with blood in reverse typing?
To determine the blood type of the sample.
What is a key advantage of the KM color test regarding the sample?
It is not destructive to the sample, allowing for further tests.
What happens to starch when it forms a complex with iodine?
It produces a blue color.
What bond does the B allele form?
Joins D-galactose to D-galactose.
What is required to prepare a reagent for the precipitin ring test for human blood?
Antiserum against human blood.
What is used to prevent blood from coagulating?
Anti-coagulants like EDTA, heparin, and citrate.
What is the significance of the PSA test in forensic analysis?
It serves as a confirmatory test for a positive AP test sample.
What is a key advantage of the Phadebas test?
No special apparatus is required, allowing it to be used at the scene.
Does the Luminol test interfere with subsequent DNA testing?
No, it does not interfere.
Is the test for detecting vaginal secretions conclusive?
No, it is not conclusive due to variability in glycogen levels.
What do confirmatory tests for blood rely on?
A reaction between a chemical and the hemoglobin molecule in red blood cells (RBC).
What is the significance of diffusion in the PSA test?
It allows the antibodies to interact with the PSA in the sample.
How are A and B alleles related?
They are codominant.
What color change indicates a positive result in the KM color test?
Colorless to pink.
What is the purpose of measuring the size of clear areas in the test?
To determine the relative amount of amylase in the samples.
What is the characteristic of the O allele?
Contains a deletion that results in a loss of enzymatic activity.
What process is used to separate components of blood?
Centrifugation.
How can antibodies against human blood be produced?
By injecting human blood into a rabbit or other animals.
