Forensic Genetics

Question 1

Forensic Genetics Outline

Answer 1

Gather and analyse DNA at crime site. Sees if it supports other evidence through genetic profile

Question 2

DNA Source

Answer 2

Blood, Semen, Saliva, Hairs, Epithelial cells, Weapon handles and clothing

Question 3

Current Methods of Analysing DNA Evidence

Answer 3

Short Tandem Repeats: reocurring nucleotides in non-coding region. Genetic profile: 16 STRs + 1 sex determining region (1 in a million chance of a false positive)

Question 4

STR Steps

Answer 4

Examine evidence, DNA collection, DNA extraction, DNA quantification & amplification, DNA Sequencing and Match search

Question 5

What Reagents are Used For Blood Id

Answer 5

Luminol, Blue Star, Kastle, Meyer, Hematrace

Question 6

Saliva ID Reagents

Answer 6

Phadebas

Question 7

Semen ID Reagents

Answer 7

RSID + Microscopy

Question 8

DNA Quantification & Amplification

Answer 8

qPCR

Question 9

Traditional DNA Sequencing

Answer 9

Capillary electrophoresis. Negatively charged DNA is repelled away from the cathode and attracted to anode. Gel separates particles based on size (small particles move through faster). Amount of time passed and fluorescence type when it passes through laser

Question 10

How is a homozygous individual evaluated with STR

Answer 10

2 of the same STR count

Question 11

How is a heterozygous individual evaluated with STR

Answer 11

2 different STR counts

Question 12

DNA Database

Answer 12

Profiles from convicts, suspects and references (people who was in contact with scene/sample for contam eval) are stored electronically and compared from crime scene

Question 13

Limitations of DNA Database

Answer 13

Only works if profile is already in database & DNA is too easily transferable (high false positive risk)

Question 14

Novel DNA Profiling

Answer 14

NGS: SNPs and Mitochondrial

Question 15

How Does NGS Work

Answer 15

DNA sample fragmented, sample bound with molecular barcode, DNA unwinds, DNA attached flow cell, PCR amplification (samples may be mixed but are differentiated based on barcode)

Question 16

NGS in Forensics

Answer 16

Criminal casework, Cold cases, Phenotyping (and age estimation methylation), Disaster victim ID, Missing people. Able to analyse samples: degraded, mixed or limited DNA samples

Question 17

How to Differentiate between monozygotic twins

Answer 17

Deg5ree of methylation (influenced by enviornment and lifestyle)

Question 18

Mitochondrial DNA Sequencing Outline

Answer 18

Used in degraded samples (eg hair without root), maternal inheritance. Limitations: Follows maternal lineage, too broad to specifically identify 1 person

Question 19

Genetic Geneaology Outline

Answer 19

Inferring genetic relationships between people. Can be STR, SNP & mitochondrial sequencing. STR is limited only to biological sibling and parents

Question 20

Applying NGS to Burials

Answer 20

Old bones (degraded DNA), Mt Sequencing, SNP/STR/NGS (combine for better resolution)