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DNA & Blood > Exam > Flashcards

Exam Flashcards

1
Q

Antigen

A

A substance that stimulates the body to produce antibodies against it

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2
Q

Antibodies are contained in the RBCs T/F

A

False

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3
Q

What revolutionary technique replaced blood typing for associating bloodstain evidence with a particular individual?

A

DNA

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4
Q

What are the 4 important antigens?

A

A, B, O, D

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5
Q

Agglutination is associated to what?

A

Incompatible blood types

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6
Q

What system is used currently for properly matching a donor and recipient for a transfusion?

A

ABO system

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7
Q

What percentage of blood content does plasma account for?

A

55

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8
Q

Karl Landsteiner discovered that blood can be classified by its what?

A

Type

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9
Q

What is the fluid portion of unclotted blood called?

A

Plasma

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10
Q

What kind of structure does DNA have?

A

Double helix

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11
Q

What is an example of the best current presumptive search technique that results in chemiluminescence which can last for several minutes?

A

Bluestar

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12
Q

Mitochondrial DNA is found outside the nucleus of the cell and is inherited solely from the father T/F

A

False

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13
Q

DNA is a molecule that is formed by linking together a series of repeating units known as what?

A

Nucleotides

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14
Q

Complimentary base pairing refers to what?

A

G always pairs with C and T always pairs with A

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15
Q

G always pairs with C and T always pairs with A is a fact that refers to what?

A

Complimentary base pairing

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16
Q

When is a P30 test performed?

A

When no sperm are found to be present within the sample

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17
Q

What is the building block for the human body?

A

DNA

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18
Q

Each nucleus of a cell contains how many chromosomes?

A

46

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19
Q

No two people have the same DNA T/F

A

False - identical twins have the same DNA

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20
Q

Where can a reference sample of mtDNA be obtained?

A

From any maternally related relative

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21
Q

During a sexual assault, for example, biological evidence such as hair, skin cells, semen, or blood can be left on a victim’s body or other parts of the crime scene T/F

A

True

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22
Q

Mitochondrial DNA is found inside the nucleus of the cell and is inherited solely from the mother T/F

A

False

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23
Q

Where is mtDNA found and inherited from?

A

Found in the mitochondria of every cell (not in the nucleus!) and inherited solely from the mother

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24
Q

How many nucleus vs mitochondria in each cell?

A

Only one nucleus but hundreds of thousands of mitochondria

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25
Q

Who may elimination samples be taken from?

A

Anyone who had lawful access to the crime scene and may have left biological material

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26
Q

All individuals of the same maternal lineage are what by mtDNA analysis?

A

Indistinguishable

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27
Q

Crime scene DNA samples are compared to suspect’s DNA for the presence of what?

A

A set of specific DNA markers

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28
Q

What do elimination samples help to do?

A

Determine if the evidence is from a suspect or another person

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29
Q

If multiple swabs are collected, they all should be packaged and sealed in the same container to avoid cross contamination. T/F

A

False

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30
Q

What should you do if the stained object is transportable?

A

Submit the item intact

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31
Q

In crimes of violence, how is blood usually found?

A

In the form of dried stains

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32
Q

The exact location of blood samples and controls are calculated by triangulating transient objects T/F

A

False

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33
Q

In addition to identification and comparison testing, what else may provide information concerning how blood was deposited?

A

The shape and pattern of the blood staining

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34
Q

Collection of suspected dry blood stains requires the swab to be preferably moistened with distilled water T/F

A

True

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35
Q

What should be collected as a control for bloodstains?

A

An unstained area adjacent to the suspected bloodstain

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36
Q

What is used to collect liquid blood?

A

A dry sterile swab

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37
Q

After collecting a suspected dry blood stain, it is not necessary to air dry since it was a dried stain T/F

A

False - the swab was moistened so it needs to be dried

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38
Q

What kind of container is wet swabbed blood packaged in?

A

Porous

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39
Q

Using an alternate light source (ALS) to detect semen at a crime scene is foolproof as a confirmatory test T/F

A

False

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40
Q

In a rape case, investigators can collect and analyze DNA of any consensual sexual partner from only the past day T/F

A

False

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41
Q

The crime scene investigator need not attempt to recover articles associated to a sexual assault crime scene since the victim will be examined by a medical professional to recover sufficient DNA to identify the perpetrator T/F

A

False

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42
Q

Another confirmatory test is known as a P30 test. This test is performed for the presence of spermatozoa T/F

A

False

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43
Q

What is the ideal way to preserve biological evidence?

A

Freeze it

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44
Q

Evidence with dried biological stains should be stored in a room without temperature control T/F

A

False

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45
Q

Saliva stains are not usually evident from a visual examination. However, certain types of evidence frequently contain traces of saliva such as what?

A

Bite marks

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46
Q

Where are confirmatory tests for semen done?

A

Can only be done in the lab

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47
Q

In all cases, it is essential to have the victim examined by a medical professional as soon as possible T/F

A

True

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48
Q

What other substances with fluoresce similar to semen?

A

Fabric softeners, toothpaste, sweat

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49
Q

What does BPA stand for?

A

Bloodstain pattern analysis

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50
Q

What is bloodstain pattern analysis?

A

The science of examining and interpreting blood present at a bloodshed event in order to determine what events occurred, in what order, and who possibly left the stains

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51
Q

In what shape does blood fall?

A

Sphere

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52
Q

How do bloodstains dry?

A

From the outside towards the inside

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53
Q

What end of an elongated bloodstain will typically point in the direction of travel?

A

Tail/narrow/tapered

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54
Q

Where does the tail/narrow/tapered end of an elongated bloodstain typically point?

A

In the direction of travel

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55
Q

The more viscous a fluid, what?

A

The slower is flows

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56
Q

Should you include the tail when measuring the length of a bloodstain?

A

No

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57
Q

What does it mean if a resulting bloodstain is circular?

A

The blood impacted the surface at 90 degrees

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58
Q

If an investigator were to draw an imaginary line through the long axis of bloodstains in the opposite of observed travel, they would arrive at the point in which the event occurred. This point is known as the what?

A

Area of convergence

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59
Q

In a crime scene, the direction that blood travelled, determined by the bloodstain’s shape is known as what?

A

Directionality

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60
Q

What is directionality?

A

The direction that blood travelled

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61
Q

What will allow the crime scene investigator to determine the direction from which the blood originated?

A

Careful analysis of bloodstain shapes, characteristics, and patterns

62
Q

What is the fluid part of blood?

A

Plasma

63
Q

What is suspended in plasma?

A

RBCs, WBCs, platelets

64
Q

What do the fibre solids in blood do?

A

Help clot

65
Q

What is serum?

A

The yellow liquid that separates a scab from the blood. This is where we find the antibodies.

66
Q

What are antigens?

A

Structures on the RBCs that dictate the blood type

67
Q

B antigen dictates what blood type?

A

B

68
Q

Explain the relationship between antigens and antibodies

A

With each antigen, the body creates antibodies to protect from enemy blood, by causing clotting to trap them

69
Q

What is D antigen for?

A

Rh factor (+ or -)

70
Q

What about luminol?

A

Fuck luminol, we use Bluestar

71
Q

What is used as a presumptive test for blood in the field?

A

Bluestar

72
Q

What are RBCs called?

A

Erythrocytes

73
Q

What are WBCs called?

A

Leukocytes

74
Q

Where are antigens located?

A

On the surface of RBCs

75
Q

What are antigens responsible for?

A

Blood type characteristics

76
Q

What are the most important blood antigen systems?

A

ABO and Rh

77
Q

A antigen dictates what blood type?

A

A

78
Q

What antigen does someone have if they have O type blood?

A

Neither A or B

79
Q

What antigen does someone have if they have AB type blood?

A

Both A and B

80
Q

Anti B can be found in which blood type?

A

A

81
Q

Anti A can be found in which blood type?

A

B

82
Q

Which antis are found in AB blood?

A

None

83
Q

Which antis are found in O blood?

A

Both A and B

84
Q

Which antigen does Rh+ have

A

D

85
Q

What does it mean if someone does not have D antigen?

A

Rh-

86
Q

How much of the DNA do we need to look at?

A

Only a part, then it repeats

87
Q

How many pairs of chromosomes in a nucleus?

A

23

88
Q

How can DNA be used in forensics?

A

To both convict and exonerate, can place a suspect at the crime scene

89
Q

What does CODIS stand for?

A

Combined DNA Index System

90
Q

What is CODIS?

A

An electronic database of DNA profiles administered throughout the FBI

91
Q

What categories of persons are entered into CODIS?

A

Convicted offender, arrestee, forensic, missing, unidentified, biological relatives of missing persons

92
Q

Where is DNA vs mtDNA found?

A

DNA is found in the nucleus, mtDNA is found in mitochondria

93
Q

When does DNA evidence need to be collected?

A

Any time it may be present and ASAP

94
Q

How much blood should you obtain when swabbing a sample?

A

As much as you can get on the swab

95
Q

Can swabs from the same sample be packaged together?

A

Yes

96
Q

What needs to be done to collect a dry blood sample?

A

Wet the swab with 1-2 drops of distilled water, let it dry before packaging

97
Q

How is wet blood collected?

A

With a dry swab, let the blood dry before packaging

98
Q

How should you dry a wet blood swab?

A

Air dry

99
Q

What kind of packaging should be used for biological materials?

A

Porous

100
Q

When should observations about blood stains be made?

A

Before taking samples

101
Q

How can you tell the difference between wet and dry blood?

A

Wet blood is shiny and dry blood is dull

102
Q

How should a blood swab sample be packaged?

A

In a tube, in a sealed swab box, and then the box is packaged

103
Q

Why do porous packaging materials need to be used in biological samples?

A

To prevent bacteria and mold growth that will destroy the sample

104
Q

What should you do if you do not have distilled water to take a sample?

A

Use what you have but make a note and provide a control sample of the water you used

105
Q

Where are presumptive vs confirmatory tests done?

A

Presumptive at scene, confirmatory in lab

106
Q

How can you see semen fluoresce?

A

With an alternate light source due to the acid phosphatase and amylase

107
Q

How can you see blood fluoresce?

A

Bluestar

108
Q

What are the two presumptive tests for semen?

A

Christmas tree stain for spermatozoa and p30 test for fluid

109
Q

What are we testing bite marks for?

A

Cells for DNA, saliva (not really though)

110
Q

What is the time frame for DNA collection in SA cases?

A

4 days, ASAP though

111
Q

Who do we need elimination samples for in a SA case?

A

Consensual partners

112
Q

Who collects evidence in a SA case? How?

A

Hospital staff, with a SA kit

113
Q

How should a used condom be stored?

A

In the freezer (because you can’t air dry it)

114
Q

How can DNA be obtained from a known SA suspect?

A

With a DNA warrant or doctor DNA swab of the penis (within 2 days without a shower)

115
Q

What are satellite stains?

A

Little splatter stains surrounding a large central ones

116
Q

Area of Convergence

A

2D, measured through the centre of the bloodstain through the tail of each satellite stain, where these lines meet

117
Q

Point of Origin

A

3D, using lines from point of origin direction as well as angle calculation, approximate location of the blood source when it was impacted

118
Q

How is angle of impact calculated?

A

width/length, look at sin table

119
Q

Why does blood fall in a spheroid configuration?

A

Viscosity - the blood molecules are attracted to one another and want to stick together

120
Q

What are the 3 primary things to observe when investigating bloodstains?

A

Size, shape, and distribution of the bloodstains

121
Q

Directionality

A

The direction that blood was travelling

122
Q

What way does the tail of an elongated bloodstain point?

A

In the direction of travel

123
Q

Effect of height on bloodstain size

A

Bloodstains progressively get bigger as height increases (until 7 feet)

124
Q

Terminal velocity

A

When the force of air resistance equals the force of gravity. Bloodstains will no longer get bigger with height. Reached at 7 feet.

125
Q

Passive bloodstains

A

Clots, drips, flows, blood pools. Aftermath of the violence

126
Q

Drip Patterns

A

Result from blood dripping into blood, generally satellite staining

127
Q

Size of satellite stains

A

Decrease in size as distance from blood pool increases

128
Q

What does the presence of clots within a bloodstain pattern indicate?

A

That some time elapsed between the event that resulted in bloodshed and clot formation

129
Q

When does pooling occur?

A

When gravitational forces pull blood to the lowest level possible and an accumulation of blood develops

130
Q

Where is a transfer pattern heaviest?

A

In the portion that was deposited first

131
Q

Swipe

A

When a bloodied surface rubs across a non-bloodied one

132
Q

Wipe

A

When a non-bloodied surface rubs across a bloodied surface

133
Q

When does pattern transfer happen?

A

When an object wet with blood comes into contact with a secondary surface

134
Q

How are projected patterns produced?

A

By blood released under pressure

135
Q

Cast off patterns

A

Created when blood is thrown from a blood-bearing object in motion

136
Q

How can cast-off patterns be used

A

To estimate the minimum number of blows

137
Q

Blood Spatter

A

A random distribution of bloodstains that vary in size and may be produced by a variety of mechanisms, varies considerably

138
Q

Arterial Spurt

A

When blood is projected from a breached artery

139
Q

What pattern is sometimes seen in arterial spurts?

A

V shape

140
Q

Expirated patterns

A

Created when blood is blown out of the mouth or nose

141
Q

Impact Patterns

A

Created by a force that results in the random distribution of smaller drops of blood

142
Q

What are the 3 types of impact patterns?

A

Low velocity, medium velocity, high velocity

143
Q

Skeletonized stain

A

When the centre part of a dried bloodstain flakes away or the centre part of a partially dry bloodstain is wiped away, leaving the dried outer rim

144
Q

When does blood break into smaller droplets?

A

Only when something disrupts the surface tension

145
Q

Acid phosphatase colour test

A

To locate and characterize a seminal stain. Acid phosphatase in semen turns purple.

146
Q

Christmas Tree Stain

A

Stains head of spermatozoa red and tail green. No colour change if no spermatozoa in the semen

147
Q

Semen vs spermatazoa

A

Semen is the transfer medium for spermatazoa

148
Q

Where is p30 protein found?

A

In seminal plasma

149
Q

Flow Patterns

A

Generally observed when volumes of liquid blood move freely along a downward path due to gravity or movement of the surface

150
Q

Void Pattern

A

Area where no blood is found, usually a result of an individual or item between the area of impact and surroundings blocking spatter patterns

151
Q

Fly and insect spots will not be present at a bloodletting scene T/F

A

False - there is activity of flies within a crime scene

152
Q

It may be possible to detect the victim’s DNA on the male’s underwear or on a penile swab of the suspect within what time frame of the assault?

A

24 hours

DNA & Blood (1 decks)

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