Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Forensic Biology > Exam 2 > Flashcards

Exam 2 Flashcards

Master

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

Where is DNA located in the tooth?

A

tissues in the dental pulp contain multiple cells where DNA can be isolated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what will dental pulp do in higher temperatures?

A

it will decompose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

cementoblasts

A

cells that make the cementum
contain nuclei and mitochondria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Ondontoblasts

A

only consist of mitochondria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Teeth for DNA analysis

A

take DNA from the root portion of the tooth but leave the crown

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Serology

A

the study of serum or other bodily fluids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is blood typing?

A

evaluates the antibodies associated with different blood types

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is forensic serology?

A

portion of forensic biology that deals with the examination and identification of biological evidence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Forensic serology identifies what types of bodily fluids?

A

blood, semen, saliva and more

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Different bodily fluids are associated with what?

A

Different crime scenes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Identifying bodily fluids can help link cases together or help demonstrate what?

A

possible intent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Forensic serology does not lead to any individualization of evidence, but may lead to what?

A

an exclusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

presumptive test

A

indicates the possibility of the presence of a specific body fluid
identify what the specimen could be

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Advantages of presumptive tests

A

rapid
sensitive
simple
often can be implemented at the scene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Disadvantages of presumptive tests

A

not specific

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Confirmatory test

A

more specific and allows an investigator to say within a reasonable degree of certainty that the sample is a certain bodily fluid
identifies what the specimen is

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Forensic Serology Workflow

A

Blood stain
Visual Examination
Presumptive Assay
Choice 1= Confirmatory Assay
Blood Identified
DNA Profiling
Choice 2= Species Identification
Human Blood Verified
DNA profiling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Factors that alter decision in deciding what test to use

A

Time
money
procedures
experience
sample amount
circumstances and more

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Blood is what % of the weight of a healthy human

A

8%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Blood is made of what two portions

A

Plasma and Cellular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Plasma

A

55% of blood volume

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Cellular

A

red blood cells, white blood cells, and platelets

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

White blood cells

A

Leukocytes
have nuclei (main source of nuclear DNA from blood)
help body fight infections

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Platelets

A

Thrombocytes
do not have nuclei
play a role in blood clotting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

red blood cells

A

Erythrocytes
typical life span is 3-4 months
no nuclei
contains the protein hemoglobin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Hemoglobin

A

protein responsible for transportation of oxygen
adult hemoglobin consists of four subunits
Each subunit contains a heme moiety that binds oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Heme molecule

A

ferroprotoporphyrin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Heme

A

has multiple derivatives that are utilized in testing
can bind to other chemicals like carbon monoxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

carbon dioxide binds to what

A

globular protein structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Presumptive blood assays

A

designed to identify traces of blood
can detect as little as 10 to the -5 power to 10 to the -6 power, fold dilutions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

presumptive blood assay tests are based on what

A

based on the oxidation reduction reaction catalyzed by the heme moiety of hemoglobin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

oxidation reaction is visualized as what

A

a chemiluminescent, fluorescence, or change of color

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Presumptive blood tests are often what?

A

oxidation reduction reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Oxidation reduction reactions

A

heme is the catalyst
hydrogen peroxide is the oxidant
colorless substrate (indicator)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

If heme is present, what happens

A

the colorless substate is oxidized creating a colorful, chemiluminescent, fluorescent and product

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Equation for heme?

A

AH(little6) (colorless) + H(little2)O Heme A(color) + 2H(little2)O

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Colorimetric Assay

A

Kastle-Meyer
result is an oxidized derivative, phenolphthalein, which appears pink under alkaline conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Phenolphthalein Assay

A

Kastle-Meyer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Phenolphthalein

A

catalyzed by heme with hydrogen peroxide as the oxidant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Colorimetric Assay: Leucomalachite Green

A

LMG
Produces a green color

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Leuco base form is catalyzed by heme with what as the oxidant under acidic conditions?

A

hydrogen peroxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Leucomalachite green reduced

A

colorless

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

malachite green oxidized

A

blue-green

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Hemastix

A

contains tetramethylbenzidine (TMB) and hydrogen peroxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Hemastix strip

A

moistened and rubbed on a suspected blood stain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What color indicates the presence of blood in a hemastix strip?

A

TMB(red)= yellow
TMB(ox)= green

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Chemiluminescent assay

A

emits light as a result of a chemical reaction
like a glow stick

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Fluorescent Assay

A

requires exposure of the fluorescein to a certain wavelength of light
like plastic stars that fluoresce under black light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

Advantages of assays

A

can be sprayed over large areas
very sensitive
in many cases does not interfere with downstream DNA applications

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Disadvantages of assays

A

small stains may be diluted to a point that limits detection by the spray

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

false positive

A

strong oxidants= false positive
catalyze reaction in absence of heme
ex: hair coloring products, bleach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

Any plant that contains what can catalyze an oxidation reaction leading to a false + result

A

a peroxidase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Plant peroxidases

A

sensitive to heat
heat will inactivate the peroxidases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

False negatives

A

strong reductants= false negative
much less common than false positives
ex: lithium and zinc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

What will form in the presence of heme molecules

A

crystals of certain chemicals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

Morphology of crystals

A

distinctive for heme, can be compared to a known standard for confirmation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

confirmatory tests for blood disadvantages

A

not as sensitive as presumptive tests
not specific for human blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

Heme and its Derivatives

A

Protoporphyrin IX
Heme
Hemochromagen
Hematin Hydroxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

Hemocromagen Crystal Assay

A

stain is treated with pyridine and glucose to form crystals of pyridine ferroprotopophyrin
crystals are red
also known as Takayama crystal assay

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

Hematin Crystal Assay

A

specimens are treated with a glacial acetic acid and salts, then heated forming hematin chloride
forms a brown crystal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

What is similar between hemochromagen and hematin crystal assays?

A

similar sensitivity and specificity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

What assay performs better on aged samples?

A

hematin crystal assay

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

2 things that make up semen

A

seminal fluid and sperm cells (spermatozoa)
10^7 to 10^8 spermatozoa per mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

Seminal fluid is a mixture of glandular secretions

A

60% is seminal vesicle fluid(glow under uv light) contains flavin
30% consists of prostatic fluid secretions, contains acid phosphate and prostate-specific antigen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

Three main features to spermatozoa

A

head
midpiece
the tial (flagellum)

65
Q

Acid Phosphate used in semen screening

A

marker for monitoring prostate cancer
same test used in forensics
under dry conditions stable for 1 year

66
Q

Prostate-Specific Antigen semen screening

A

used as a clinical marker for cancer
present in other tissues at lower levels
under dry conditions stable up to 3 years

67
Q

ALS

A

used to enhance stains
sources between 450 nm and 495 nm are used and then filtered with orange goggles

68
Q

Ap activity is found where

A

prostate and other fluids like urine and fecal matter

69
Q

AP techniques

A

catalyzes the removal of a phosphate group from a substrate, making a colored precipitate

70
Q

AP techniques with Fast Blue

A

in the presence of, AP will react to form a purple precipitate

71
Q

Fast blue results

A

if color change occurs under 1 min, semen is detected
if over 1 min, means that possibly non-prostate AP is present

72
Q

Christmas Tree Stain

A

Red Stain: Nuclear Fast Red (NFR) which stains the nuclei of the sperm
Green Stain: Picroindigocarmine (PIC) which stains the neck and tail of sperm

73
Q

Identification of Prostate-Specific Antigen

A

immunochromatographic method
three main components: PSA antibody in the sample well, PSA antibody in the test zone, and Antiglobulin that recognizes the antibody is in the control zone

74
Q

Control zone

A

C
Detects if the sample was loaded
to be valid, C band must appear on the test

75
Q

Treatment zone

A

T

76
Q

where Sample is loaded

A

S

77
Q

Biology of saliva

A

water, electrolytes, proteins, antibodies, and enzymes

78
Q

enzyme amylase

A

breaks down carbohydrates such as starch

79
Q

Two major forms of human amylase

A

Human salivary ( HSA)
Human pancreatic (HPA)

80
Q

Presumptive assay for saliva

A

ALS
Microscopic examination of epithelial cells
Starch iodine assay
phadebas reagant

81
Q

Visual examination of epithelial cells

A

buccal swab
histological staining

82
Q

Starch is present=

A

stay yellow

83
Q

starch iodine test basics

A

dark color indicates presence of starch
no starch=amylase is present

84
Q

Phadebas Reagent

A

used to detect amylase
produced in tablet form
amylase present=blue color

85
Q

RSID-Saliva

A

immunochromatographic assay
labeled anti-HSA antibody is contained in a sample well
anti-HSA antibody immobilized onto the test zone
antiglobulin that recognizes the antibody onto the control zone

86
Q

Description of RSID-Saliva test

A

very sensitive
human specific
rapid
deployable in the lab or in the field

87
Q

Steps in DNA Processing

A

DNA Extraction
DNA quantification
DNA amplification
Electrophorese is
DNA analysis

88
Q

Nuclear DNA

A

found in the nucleus and chromosomes
22 pairs or autosomal, 1 pair of sex chromosomes
Linear, long, diploid, unique

89
Q

Mitochondrial DNA

A

located in the mitochondria
circular, relatively short, haploid, maternally inherited

90
Q

method of DNA extraction choice must yield

A

sufficient quality
good quality DNA
high purity of DNA

91
Q

What are you always doing in a forensic setting?

A

isolating total cellular DNA

92
Q

DNA extraction techniques

A

cell and tissue disruption
lysis of cellular and organelle materials
removal of proteins
DNA storage

93
Q

the animal cell

A

open cell membrane to gain access to nucleus
break down nuclear membrane
DNA is encapsulated in proteins, helps protect it
break down chaperone proteins and purify DNA in an environment that protects it

94
Q

cell tissue and disruptions

A

goal is to gain access to the cells containing DNA

95
Q

Lysis of Cellular and organic membranes

A

one cells are accessible, need to disrupt the cell membranes, organelles, and proteins
Lysis is performed with salts, detergents (SDS) and enzymes heat
needs to be performed in a buffer

96
Q

Removal of proteins

A

remove all and any impurities that will interfere with DNA analysis
“Washing steps”

97
Q

Sample storage

A

extracted DNA needs to be stored to prevent degredation
-20 C to -80 C

98
Q

Types of sample contamination

A

processing individual to sample
sample to sample
amplified DNA and Non-amplified DNA

99
Q

Systematic Checks

A

use of a pre- and post PCR room
separate processing of evidence and reference samples
use of DNA free-reagents
everyone in the lab submits a DNA sample

100
Q

methods of DNA extraction

A

Phenol-Chloroform (organic) Extraction(solvent based)
Chelex (boiling based)
Silica based methods

101
Q

Proteinase

A

enzyme that breaks down proteins

102
Q

removal of proteins

A

mixture of phenol, chloroform, and isoamylalcohol is added
Aqueous solution=water

103
Q

DNA is precipitated out by using what

A

salts and ethanol

104
Q

Pros of Organic extraction

A

extracts large double stranded DNA
Good quality
good yield
often considered the “gold standard” in terms of quality and yield

105
Q

Cons of organic extraction

A

laborious
hazardous
multiple tube transfers( up the chances of making an error during extraction)

106
Q

Chelex

A

ion-exchange resin composed of styrene divinylbenzene copoylmers
it will bind any divalent 2+ metal cations

107
Q

DNases

A

nucleuses that degrade DNA

108
Q

Chelex procedure

A

washing
boiling
centrifugation

109
Q

washing step

A

only necessary if there is a known inhibitor for DNA amplification
higher quality=higher yielding samples

110
Q

boiling

A

5-10% solution of chelex is added
incubation
leaves DNA single stranded due to heat

111
Q

Pros of Chelex

A

Simple
rapid
one-tube
cheap

112
Q

cons of chelex

A

single stranded DNA
very fickle

113
Q

Silica-based method

A

DNA is reversibly absorbed on to silica surfaces in the presence of chaotropic salts

114
Q

Pros of silica-based methods

A

high quality DNA
double stranded DNA
amenable to automation

115
Q

Cons of silica-based methods

A

expensive
multiple tube transfers

116
Q

Spermatozoa

A

male

117
Q

Epithelial Cells

A

female

118
Q

Pre-PCR

A

DNA extraction
DNA Quantification
DNA amplification

119
Q

Post-PCR

A

Electrophorese is
DNA analysis

120
Q

PCR

A

the exponential amplification of specific sequences of DNA
Amplified DNA=amplicon

121
Q

DNA Structure

A

Deoxyribose(sugar)
Phosphate group
nitrogen base (a,t,c,g)

122
Q

DNA strands are antiparallel

A

5’-3’
3’-5’
opposite of nitrogen base

123
Q

individual nucleotides are linked by what

A

phospholipid bonds

124
Q

phosphate group does what to DNA

A

gives it a negative charge

125
Q

DNA bases

A

linked by hydrogen bonds

126
Q

Characteristics of DNA

A

double stranded
synthesized (made) in the 5’ to 3’ direction
each strand is antiparallel to opposite strand
each strand is complementary to its adjacent strand

127
Q

A/T; C/G are held together by what

A

hydrogen bonds= weak, allowing breakdown to one strand if needed
HEAT!!!!

128
Q

2 requirements of renaturation of DNA

A

Must have charged molecules (salts) to neutralize the - charge of DNA
A temperature high enough to disrupt random base pairing, but low enough to allow the strands to come together

129
Q

Basics of PCR

A

Works predominantly, can go to one strand back to two strands
when denatured, 2 single strands can be used as templates for the creation of new strands

130
Q

5 important components for DNA amplifications

A

Template DNA: Starting material
Primers: small fragments of DNA, allows amplification to be specific
Taq Polymerase: enzyme can add bases to new strand
Deoxyribonucleoside triphosphates (dNTP’s): bases added by taq polymerase enzyme
Cofactors (divalent cations): required for the enzymatic activity of the polymerase; ex: mg2+

131
Q

Template DNA

A

starting material for the reaction
multiple copies are synthesized
if quality is poor, amplification will fail

132
Q

Primers

A

18-25 nucleotides of DNA attach to the denatured strands
flank the region of interest
only attach to specific region
allows for amplification of specific region of DNA

133
Q

Polymerase

A

enzymes that take small subunits and bond together to form a larger molecule

134
Q

Taq

A

adds the dNTPs to the newly synthesized DNA
special polymerase isolated from the bacterium Thermicus aquaticus
work at a range of temp. including very high ones
moves down the strand (5’ to 3’) adding the complementary base

135
Q

Deoxyribonucleoside Triphosphates (dNTPs)

A

the new bases that will be added to the newly synthesized strands by the Taq polymerase (dATP, dTTP, dCTP, and dGTP)

136
Q

Cofactors

A

required by Taq Polymerase to be activated
same principle as discussed with nucleuses, instead this is an enzyme you want to work in the amplification process

137
Q

Cycling parameters

A

DNA can denature and renature by changing the temperature
higher temp=single strand
lower temp=double strand

138
Q

3 different cycles that are repeated

A

Denaturing (94-95 C) : double strand=single strand
Annealing (50-60 C): primers attach to single strand DNA
Extension (~72 C) : Taq polymerase adds new bases to new strand

139
Q

Quality control for PCR

A

very sensitive
procedures
pre-PCR and post-PCR
PPE needs to be worn
reactions are performed in a chemical hood
1. - control (all reagents but no DNA)
2. + control (known DNA sample)

140
Q
  • control
A

should not produce a DNA profile or indicate DNA being present

141
Q

+ control

A

produce the expected DNA profile
if p + control does not yield the expected, all of the samples ass. are rejected

142
Q

What does + control ensure

A

that the reagents and procedures work correctly

143
Q

what does - control check for

A

contamination during the PCR procedure

144
Q

DNA Quantitation

A

determining the amount of DNA you have after extraction
0.5 to 2.0 nanograms to the PCR reaction
“goldilocks” principle

145
Q

What makes a good quantitation method

A

Human specific
accurate
validated

146
Q

3 dif. types of DNA quantitation

A

slot blot procedures
intercalating dyes
quantitative PCR methods (real time PCR)

147
Q

Intercalating Dyes

A

fits in between two parts
certain dyes that intercalate between base pairs of DNA without breaking the double stranded structure
dyes are fluorescently labeled

148
Q

Intercalating Dye: PicoGreen

A

used to quantitate dsDNA samples
not human specific
measured with spectrophotometer

149
Q

Quantitative PCR Assays

A
  1. End point PCR: measures the amount of PCR product at the end of the PCR reaction
  2. Real-time PCR: measures the amount of PCR product as the reaction is occurring; often measured during the exponential phase of the reaction
    advantageous because it allows for the detection of inhibitors which provides more information prior to further processing
150
Q

Different Phases of PCR

A

4 phases
Lag: beginning. amt of amplification is slow
Exponential: number of amplicons increase a lot
Linear: Amplification begins to slow due to reagents become limited
Plateau: no more amplification, reagents no longer available

151
Q

End Point PCR

A

Analyzes the amount of DNA after PCR is completed
samples are amplified

152
Q

Real time PCR

A

analyzes amount of each target after cycle
sensitive
automated
quantify different portions of DNA
detection of PCR inhibitors

153
Q

TaqMan Method

A

uses a probe that binds within the amplified region of DNA
Binding happens after double stranded DNA has become single stranded
probe has a reporter dye (R) and a quencher dye (Q)

154
Q

How TaqMan Works

A

if separated, Reporter will fluoresce
5’ exonuclease activity
during extension phase, taq cuts off the reporter allowing it to move away from the quencher and fluoresce

155
Q

Electrophoresis

A

process in which DNA fragments are separated when placed in an electric field
relies on DNA being - charge

156
Q

what is the matrix

A

physical support that holds DNA molecules
“Molecular Sieve”
agarose and polyacrylamide

157
Q

Agarose Matrix

A

mixture of a solvent that is dissolved into a buffer
heated up to further dissolve and then cooled to form gel

158
Q

Polyacrylamide matrix

A

cross-linking gives it an extra level of resistance over agarose

159
Q

Differences in Matrices: Agarose

A

pores are large
good for separation of larger DNA fragments

160
Q

Differences in Matrices: Polyacrylamide

A

pores are much smaller than agarose
can resolve 5 to 500 bp

Forensic Biology (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions