Forensic DNA Processing

Question 1

What is forensic DNA analysis?

Answer 1

Individualization of biological substances to a certain person by DNA profiling

Question 2

What is the nucleus?

(Cells)

Answer 2

Control center of the cell

Question 3

What do nucleotides consist of?

Answer 3

1. Phosphate group
2. Pentose sugar
3. Nitrogenous base

Question 4

What are the properties of a hydrogen bond?

Answer 4

• Double strand
• A pairs with T
• G pairs with C

Question 5

How similar is human DNA?

Answer 5

99.7% identical between people

Question 6

What are genes, loci, and alleles?

Answer 6

Gene:
Segments of DNA that determine traits
Loci:
The position of a gene on the chromosome
Allele:
A variant form of a gene. Humans have 2 alleles at each genetic locus (one from mom, one from dad)

Question 7

What are short tandem repeates (STR regions)?

Answer 7

A region of DNA that is composed of short sequences of nucleotides that repeat many times

The number of repeats in the same locus vary person to person

Ex. (AATG) with 7 repeats from mom and 8 repeats from dad

Question 8

What is a homozygote vs a heterozygote?

Answer 8

Homozygote:
Both alleles are the same length

Heterozygote:
Alleles have a different length

Question 9

What is CODIS?

Answer 9

Combined DNA Index System
National DNA database in the US that allows forensic labs to share and compare DNA profiles

Goes 20 loci deep

Question 10

What are the steps of DNA analysis and their overarching functions?

Answer 10

DNA extraction:
Isolate DNA from cell
DNA quantification:
See how much was isolated
DNA amplification:
Grab the loci and make more
DNA seperation and detection:
Seperate and detect repeats
Data interpretation:
Is there a match?

Question 11

What is the process of DNA extraction?

Answer 11

Isolating the DNA within the cell and extracting it. Getting rid of all unneccesary cell aspects.

Extraction procedures:
* Organic (Phenol-Chloroform) (toxic and slow, high yield)
* Chelex (Ion exchange Resin) (fast, cheap, lower yield)
* Solid Phase Extraction (SPE)* (fast, expensive, high yield)*

Question 12

What is the purpose of differential extraction?

Answer 12

Purpose: To separately isolate the male and female DNA from sexual assault evidentiary samples

Question 13

What is the purpose of DNA quantitation?

Answer 13

To measure the quality and quantity of DNA present in a sample

Question 14

What are the steps of DNA amplification?

(ESSAY QUESTION KNOW THIS STUFF)

Answer 14

Polymerase Chain Reaction (PCR)
Making copies of an STR region
Steps:
1. Denaturation (heating samples to denature/seperate double stranded DNA)
2. Annealing (lower temp., and allow primers to anneal (recombine/bond)
3. Extension (Allow polymerase to elongate/extend the new DNA strands)

Each time the process is repeated, the DNA will double

Question 15

What is the process of DNA seperation and detection?

Answer 15

• DNA is seperated again and bonded with a fluorescent primer
• DNA is run through a capillary electrophoresis machine
• Smaller fragments move faster and are detected first
  The machine creates a STR profile

Question 16

What are the characteristics of an STR profile?

Answer 16

Each profile has multiple STR loci markers with two alleles each

Question 17

What are the three criteria of DNA interpretation?

Answer 17

Exclusion:
No match
Inclusion:
Match, cannot exclude
Inconclusive:
No result

Question 18

What is the innocence project?

Answer 18

Using new DNA technology and evidence to help demonstrate innocense post-conviction

Question 19

What is forensic genetic genealogy?

Answer 19

The use of DNA testing in combination with traditional genealogical and historical records to infer the relationship between individuals

Question 20

What are centimorgans?

Answer 20

• Unit of genetic measurement. How much DNA and the
  length of specific segments of DNA you share with
  your relatives.
• The total length of all your chromosomes combined is
  around 7400 cM
• You share about 3700 cM with each parent.

Question 21

What are the types of DNA test for genealogy

Answer 21

Autosomal DNA:
The DNA inherited from every chromosome minus your X and Y

Y-chromosome DNA:
Passed from father to son

Mitochondrial DNA:
Passed from mother to children

X-chromosome:
Son = just from mom
Daughter = one from each parent

In other words:
Males inherit an X from their mother, a Y from their father, and mitochondrial from their mother
Females inherit an X from their mother, an X from their father, and mitochondrial from their mother

Question 22

What are the types of records used to build family trees?

Answer 22

Vital records:
Birth, marriage, and death records

Draft registration records:
Important during WWI and WWII

Census records:
Collected every 10 years, released every 72 years

Question 23

What is FIGG?

Answer 23

Forensic Investigative Genetic Genealogy:

Utilizing genetic information from direct-to-consumer companies for identifying suspects or victims in criminal cases

Question 24

What are FIGG companies?

Answer 24

CODIS
AncestryDNA
UK DNA Database
23andMe
Myheritage
FamilyTreeDNA
GEDmatch

Question 25

What are the types of FIGG tests?

Answer 25

**Y-DNA:** * Looking at paternal lines **mtDNA:** * Passed through maternal lines **Autosomal DNA:** * Tracked in centimorgans * FamilyTreeDNA **X-DNA:** * Useful for both males and females * Can help include/exclude branches of the family