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Chemisrty > Forensic Serology > Flashcards

Forensic Serology Flashcards

1
Q

identification of bodily fluids. It focuses on identifying the presence of
blood, semen, saliva, or other bodily fluids in a sample.

A

L

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2
Q

commonly associated with violent criminal cases. For example, the
identification of blood evidence is often necessary for cases involving homicide, aggravated assault,
sexual assault, and burglary.

A

L

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3
Q

Individualization of biological
evidence is used to determine whether or not a bodily fluid sample has come from a particular
person.

A

H

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4
Q

can be achieved by using forensic DNA analysis. However, the identification
of bodily fluid cannot be omitted or replaced by forensic DNA analysis.

A

J

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5
Q

The identification of bodily fluid can be carried out using presumptive and confirmatory assays to
test that the sample is the bodily fluid in question.

A

H

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6
Q

advantages of presumptive assays are that
these assays are sensitive, rapid, and simple.

A

H

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7
Q

negative assay suggests that the
questioned bodily fluid is absent.

A

J

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8
Q

positive reaction of a presumptive assay indicates the possibility of the presence of the bodily fluid
in question.

A

J

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9
Q

presumptive assays are not very specific. Therefore, they should not be
conclusive to the presence of a type of bodily fluid

A

I

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10
Q

• Thus, they can be used as a screening method and narrow down biological stains prior to other
types of analyses, such as forensic DNA testing. Moreover, these assays can be used as a search
method to locate biological stains at the crime scene.

A

J

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11
Q

. Confirmatory assays are more specific for the
bodily fluid in question. These assays are employed to identify bodily fluids with higher certainty
than presumptive assays.

A

j

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12
Q

confirmatory assays are more time consuming than
presumptive assays.

A

H

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13
Q

identification of blood can be performed using presumptive and confirmative assays.

A

N

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14
Q

The most
utilized presumptive assays among forensic laboratories are oxidation–reduction reaction assays.

A

H

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15
Q

presence of blood can then be confirmed further using confirmatory assays. The most utilized
confirmatory assays are microcrystal assays.

A

J

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16
Q

confirmatory
assays for blood identification are infrequently performed

A

J

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17
Q

reddish-
brown stain identified through visual examination is usually tested by
using presumptive assays.

A

K

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18
Q

stain is positive, the
stain is then analyzed further by forensic DNA analysis.

A

J

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19
Q

This approach
can only derive a conclusion that the results indicate the presence of
blood. Therefore, if enough biological materials are available,
confirmatory assays should be performed if possible.

A

H

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20
Q

The blood volume of a normal human is approximately 8% of the body
weight. The fluid portion of the blood is called plasma.

A

J

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21
Q

The cellular portion of the blood, which is suspended in the plasma,
consists of erythrocytes (also called red blood cells), leucocytes (also
called white blood cells), and thrombocytes (also called platelets).

A

J

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22
Q

Most presumptive and confirmatory assays of blood identification are
based on the detection of hemoglobin.

A

H

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23
Q

Each hemoglobin subunit contains a heme molecule (also called
ferroprotoporphyrin). The heme molecule consists of a protoporphyrin
IX and a ferrous (Fe2+) iron atom.

A

-

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24
Q

type of presumptive assay for blood identification is based on the biochemical properties of the
heme molecule, which can catalyze an oxidation–reduction reaction.

A

J

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25
Q

oxidation often coincides with the loss of hydrogen, and
reduction often coincides with the gain of hydrogen.

A

J

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26
Q

the most commonly used reductants

A

J

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27
Q

phenolphthalein

A

K

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28
Q

leucomalachite

A

K

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29
Q

tetramethylbenzidine

A

J

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30
Q

luminol

A

J

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31
Q

hydrogen peroxide is usually employed as an oxidant.

A

J

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32
Q

colorless reductant is oxidized, forming a product with color or chemiluminescence. Thus, a positive
reaction indicates the possible presence of blood.

A

I

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33
Q

shows a pink color in alkaline conditions.

A

J

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34
Q

green assay utilizes the leuco base form of malachite green,

A

H

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35
Q

can be oxidized
in the presence of heme to produce malachite green, which shows a green color. The reaction is carried out under acid
conditions.

A

U

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36
Q

oxidation of tetramethylbenzidine can be catalyzed by heme to produce a green
color under acidic conditions.

A

I

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37
Q

portable tetramethylbenzidine assay kit that can be used in laboratories
and at crime scenes.

A

J

38
Q

Hemastix assay (

A

I

39
Q

they are not blood specific and possibly lead to false-positive results.

A

U

40
Q

false-
positive reaction can be caused by the presence of chemicals that are strong oxidants (such as
certain metal salts), even in the absence of heme

A

0

41
Q

Plant peroxidases can also catalyze the oxidation
reaction in the absence of heme

A

I

42
Q

peroxidase-containing plants (such as horseradish) can cause
a false-positive result.

A

I

43
Q

The presumptive assays can be carried out using the

A

J

44
Q

swabbing method.

A

K

45
Q

small amount of the
questioned stain is transferred onto a moistened cotton swab. Additionally, a substance control (
swabbing a nonstained area adjacent to the stained area) can be prepared.

A

M

46
Q

Microcrystal Assays

A

M

47
Q

blood crusts from a bloodstain are treated chemically to convert native heme
to heme derivatives.

A

M

48
Q

These heme derivatives can form crystals with distinctive morphologies. The
crystal morphology of heme derivatives can be examined by using microscopic observation.

A

N

49
Q

As a
result, the presence of the crystals of heme derivatives confirms the presence of blood.

A

K

50
Q

less sensitive than the
presumptive assays for blood identification.

A

M

51
Q

the ferrous ion
of the heme can form six bonds:

A

M

52
Q

the ferrous ion
of the heme can form six bonds:

A

M

53
Q

four bonds with the nitrogen of protoporphyrin IX, one bond with oxygen, and • one bond with a hemoglobin subunit.

A

K

54
Q
A

J

55
Q

blood crusts are treated with glacial acetic acid and salts with
heating. Brown-colored prismatic crystals of ferriporphyrin chloride form. Ferriporphyrin chloride is a
heme derivative in which the iron is in the ferric (Fe3+) state.

A

K

56
Q

Takayama crystal assay,

A

N

57
Q

Teichmann crystal assay

A

N

58
Q

PCR

A

N

59
Q

When a sample of DNA is too small to be sequenced or profiled, the polymerase chain reaction (PCR) is used to make copies (“amplify “) portions of it.

A

J

60
Q

PCR amplifies DNA by repetitive cycles of the following steps.

A

J

61
Q

Denaturation

A

J

62
Q

Annealing (“priming”)

A

H

63
Q

Synthesis (“extension” or “elongation”)

A

J

64
Q

Consider double-stranded DNA containing a polynucleotide sequence (the target region) that you wish to amplify.

A

J

65
Q

Heating the DNA to about 95°C causes the strands to separate. This is the denaturation
step.

A

H

66
Q

Cooling the sample to ~60°C causes one primer oligonucleotide to bind to one strand and the other primer to the other strand. This is the annealing step.

A

H

67
Q

presence of four DNA nucleotides and the enzyme DNA polymerase, the primer is extended in its 3’ direction. This is the synthesis step and is carried out at 72°C.

A

H

68
Q

The next cycle begins with the denaturation of the two DNA molecules shown. Both are then primed as before.

A

H

69
Q

Elongation of the primed fragments completes the second PCR cycle.

A

J

70
Q

Among the 8 DNAs formed in the second cycle are two having the structure shown.

A

H

71
Q

The two contain only the target region and and are the ones that increase disproportionately in subsequent cycles.

A

H

72
Q

RNA-Based Assays for Bodily Fluid Identification

A

N

73
Q

These assays can detect specific types of messenger RNA (
mRNA) that are only present in erythrocytes

A

I

74
Q

Messenger RNA is transcribed from a gene and is then translated to produce a protein. • The erythrocyte-specific genes utilized for blood identification are HBA1, PBGD, and SPTB.

A

I

75
Q

These assays are carried out using the reverse transcription polymerase chain reaction (RT-PCR) technique to detect erythrocyte-
specific mRNA for blood identification.

A

J

76
Q

mRNA strand is used as a template for the synthesis,

A

J

77
Q

complementary DNA (cDNA).

A

J

78
Q

The advantages of RNA-based
assays are that this technique is sensitive and can be used to detect very small quantities of mRNA.

A

J

79
Q

specific and can detect erythrocyte-specific mRNA. Moreover, the technique is adaptable to automation.
The disadvantage of this technique is that the mRNA present in the sample can be degraded by endogenous ribonucleases.

A

K

80
Q

Immunochromatographic Assays

A

J

81
Q

The sample is then extracted with a
small volume of buffer.

A

I

82
Q

The extracted sample is loaded into the sample well of the
immunochromatographic device.

A

K

83
Q

The loaded sample diffuses across the
nitrocellulose membrane.

A

I

84
Q

The presence of antigens in the sample results in a colored line at the
test zone.

A

L

85
Q

immunochromatographic device also utilizes a control zone to
ensure that the sample has diffused properly along the test strip. Thus,
the presence of antigens results in a line at the control zone as well.

A

O

86
Q

The assay is considered valid only if the line in the control zone is
observed.

A

O

87
Q

false-negative result may occur in a
sample consisting of a very high concentration of antigens.

A

J

88
Q

high-dose hook effect .

A

I

89
Q

rapid, specific, and
sensitive and can be used in both laboratory and field tests for species
identification.

A

J

90
Q

based on the detection of human erythrocyte
proteins.

A

J

Chemisrty (8 decks)

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