Brainscape's Knowledge GenomeTM

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


See full index

Forensic Biology > Exam 3 > Flashcards

Exam 3 Flashcards

master

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

Fluorescent Dye functions

A

Fluorescent dye is attached to the TaqMan probe in quantitation step.
For amplification, dyes are attached to the primers
They can be used in multiplex PCR reactions

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

Singleplex PCR reaction

A

a single primer set used to amplify a single region (amplicon)

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

Multiplex PCR reaction

A

amplify over 20 loci at the same time
saves a large amount of time
can differentiate between individuals

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

How does having multiple dyes allow for multiplexing of PCR

A

It enables a clear differentiation of multiple targets, even when similar in size, by assigning fluorescence signals to each target, allowing for both simultaneous detection and better resolution in the analysis

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

How PCR products are labeled with fluorescent dyes for STR analysis

A

fluorescently labeled primers enable the differentiation of loci based on both size and dye color

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

How PCR products are labeled with a fluorescent dyes for mtDNA sequencing

A

fluorescently labeled ddNTPs allow for a sequential, base-by-base redout of the DNA sequence

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

How restriction endonucleases can be used to determine a person’s STR prodtfile

A

Restriction enzymes can be used to generate unique DNA fragment patterns based on STR length, but they lack specificity, sensitivity, and efficiency needed for reliable forensic STR profiling.

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

Basic function of restriction endonucleases

A

molecular “scissors” that enable precise cutting of DNA at specific sequences, playing a crucial role in genetic analysis, engineering, and forensic science

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

Structure of Variable Number Tandem Repeats (VNTRs)

A

consist of a sequence of DNA bases repeated back-to-back at a specific locus in the genome. Number of repeats can vary(genetic diversity)

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

Structure of Short Tandem Repeats (STRs)

A

subset of VNTRs where the repeating units are shorter, usually between 2-6 base pairs. vary in number of repeats, creating differences in length across individuals

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

Advantages of using PCR based assays in forensic investigation

A

high sensitivity
analysis of degraded samples
rapid and efficient process
ability to target specific regions
high throughput and multiplexing capability
compatibility with mixed and contaminated samples
standardization and databases
automation and portability

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

How PCR and capillary electrophoresis can be used to determine the number of repeats within an STR

A

by combining PCR to amplify STR regions and CE to separate and detect the amplified fragments, you can determine the number of repeats at each STR locus.

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

Advantages of using microsatellites over minisatellites

A

high sensitivity
efficiency
compatibility with degraded or small DNA samples
short length
ability to generate unique profiles
standardization in databases give an advantage

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

Basic information and characteristics for an STR to be usable

A

High variability
Stability and inheritance
Small size
low mutation rate
unique chromosomal locations
compatibility with PCR

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

STR types based on the number of base pairs in the repeat unit

A

Dinucleotide Repeats
Trinucleotide Repeats
Tetranucleotide Repeats
Pentanucleotide Repeats
Hexanucleotide Repeats

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

STR types based on Repeat pattern or sequence arrangment

A

Simple STR
Compound STR
Complex STR

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

STR based on Chromosomal Location

A

Autosomal STR
Y-STR
X-STR

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

Core loci

A

specific STR locations on the human genome that are routinely analyzed in forensic DNA testing.

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

why was core loci set expanded in 2017

A

Increased discrimination power
higher success rates with degraded samples
enhanced compatibility with international databases
improved kinship analysis

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

How can an internal lane standard be used to size the DNA fragments within an electropherogram peak

A

Calibration reference
Correction for variability
Fragment sizing

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

Allelic ladders and how they are used to “call” alleles for peaks

A

set of DNA fragments at a particular STR locus.
software visually compares the migration patterns of the sample peaks to the allelic ladder’s peaks

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

Steps in order to determine alleles, genotypes, and a profile

A

understanding the electropherogram
identify the loci
compare peaks to the allelic ladder
determine the alleles
determine the genotype
construct the DNA profile

23
Q

Interpret results for autosomal STR data

A

Inclusion (match): sample could come from the individual in question
Exclusion (non-match): excludes the individual as the source
Inconclusive: if sample is degraded or has low quality

24
Q

Interpret results for mtDNA data

A

Inclusion (match): cannot uniquely identify an individual
Exclusion (non-match): individual is excluded
Inconclusive
cannot exclude

25
Q

Interpret results for Y-STR data interpretation

A

Inclusion (match): includes the individual
Exclusion (non-match): excluded as a source
Inconclusive
Cannot exclude

26
Q

Identify all different factors impacting STR genotyping

A

Sample quality, PCR conditions, Allelic variation, technical limitations, human error, and genetic factors

27
Q

How Tri-allelic patterns form

A

biological mechanisms, genetic abnormalities, or technical issues

28
Q

How point mutations in the STR flanking region can impact primer binding

A

Failure to bind; STR locus will appear as a null allele
Reduced Binding Affinity; weaker PCR products
Mispriming; lead to false peaks or primer-dimer artifacts

29
Q

How point mutations in the STR flanking region can impact Amplification

A

Incomplete Amplification; partial STR profile will be generated
Allelic Dropout; genotyping errors

30
Q

How point mutations in the STR flanking region can impact STR profiling

A

Loss of information; difficult to distinguish between two individuals
False Genotyping; lead to wrong conclusions

31
Q

How strutter products are formed

A

byproducts of DNA polymerase slippage during PCR amplification of STR regions.
shorter, smaller peaks, complicate interpretations of STR profiles

32
Q

Basis of non-template adenylation

A

phenomenon where a polymerase (Taq polymerase) adds extra adenine residues to the 3’ ends of PCR products.

33
Q

Non-template adenylation and its impact on samples

A

Size shifts, false alleles, artifact peaks, or allelic misinterpretations

34
Q

Cause of Pull up peaks in electropherograms

A

signal from a fluorescent dye is used for one STR locus “pulls up” into the detection range of another adjacent peak from a different fluorescent dye or locus
spills or bleeds into adjacent channel

35
Q

Cause of Spikes in Electropherograms

A

can arise from small technical issues with the capillary electrophoresis system
contaminants like dust, bubbles
electrical noise in the detection system

36
Q

Identify a degraded DNA profile/ understand why it looks like that

A

characterized by shorter, fragmented STR products, missing alleles, and fainter peaks in the electropherogram
can be caused due to environmental factors, time, microbial activity, handling conditions, or mechanical damage

37
Q

Complications associated with low copy number DNA testing and increasing cycle numbers

A

increased stochastic effects, PCR artifacts, non-specific amplification, and a greater risk of contamination

38
Q

Characteristics and identifying mixture profile

A

multiple alleles at one locus, imbalanced peak intensities, allelic drop-out, missing or additional peaks, and complex patterns
careful interpretation is required when involved a low-quanitiy or degraded samples case

39
Q

determine possible genotypes in a mixture sample

A

evaluate the number of peaks at each locus, their relative intensities, and their possible allele pairings

40
Q

Characteristics of mtDNA

A

Inheritance
circular structure
size
coding and non-coding regions
high copy number
small number of genes
no recombination
mutability
absence of histones

41
Q

General structure of the mtDNA genome

A

The two strands
-heavy and light strand
Control region
-Non-coding region and D-loop
Origin of Replication
-Origin of Heavy strand replication
-Origin of Light strand replication
Gene Organization
-Protein-coding genes
-tRNA genes
-rRNA genes
Hypervariable Regions

42
Q

Length Polymorphisms

A

refer to variations in the length of a DNA sequence between individuals
STRs and VNTRs

43
Q

Sequence Polymorphisms

A

refers to variations in the nucleotide sequence of a given region of DNA
SNPs and Indels

44
Q

What information can be gained from mtDNA

A

maternal ancestry
degraded samples
family lineage
mothers side tracing

45
Q

what information can be gained from Y-STR

A

Y chromosome
paternal lineage
tracing male family lines
paternal relatives
ancient male migration patterns

46
Q

How the addition of ddNTPs is used to sequence regions of DNA

A

terminated DNA chain elongation at specific points=set of fragmented DNA sequences

47
Q

Why sequence PCR reactions only include 1 primer instead of 2

A

because the sequencing reaction is designed to extend one strand of DNA in the 5’ to 3’ direction. starting point for DNA polymerase

48
Q

Sequence Polymorphisms for mtDNA

A

Align the sequenced DNA to a reference
Identify differences such as SNPs, insertions, or deletions
report polymorphisms by position and type (transition, transversion, insertion, deletion)
put the findings in the context of population databases or haplogroups to provide insight into ancestry, lineage, or forensic identification

49
Q

Heteroplasmy

A

Refers to the presence of more than one type of mitochondrial DNA (mtDNA) in a single cell or organism

50
Q

How to report sequence heteroplasmy

A

Identify
document base change
quantify the proportion of each variant
contextualize the heteroplasmy

51
Q

Y-STRs are all inherited together

A

they are located in close proximity on the Y chromosome and do not undergo recombination during meiosis

52
Q

Exception to there only being one peak per locus and what causes it

A

homologous recombination or mutations that cause multiple alleles
exception occurs when there is a duplicated locus or mutations causing more than one peak at a given Y-STR marker

53
Q

Rapidly mutating Y-STRs

A

class of Y-chromosome Short Tandem Repeats that exhibit a higher mutation rate compared to typical Y-STR markers

54
Q

Rapidly mutating Y-STRs potential advantages

A

Increased resolution for kinship testing
forensic applications
Genealogical and Ancestry research
Personal Identification

Forensic Biology (3 decks)

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