Unit 2 - 13. DNA Analysis in Forensic Science

Question 1

Forensic Uses of DNA analysis

Answer 1

1. Identification of the source of biological material
2. Criminal paternity/maternity analysis
3. Identification of remains

Question 2

Specimens for DNA analysis

Answer 2

• blood
• semen
• saliva
• tissue
• hair
• teeth
• bone
• urine

Question 3

Advantages of PCR in Forensic DNA analysis

Answer 3

1. Requires small amount of sample
2. Can utilize degraded samples
3. Requires less time

Question 4

Disadvantages of PCR in Forensic DNA analysis

Answer 4

1. Susceptible to contamination due to sensitivity

2. Known artifacts must be accounted for (Stutter, Non-template addition or -A, Null Alleles)

Question 5

Sequence variations

Answer 5

• change in genetic sequence that provides allelic variation

Ex: Mitochondrial sequencing: AGCTCAAT vs. AGATCAAT

Question 6

Length Polymorphism

Answer 6

• variation in the number of repeat units STRs- autosomal and Y-chromosome

Question 7

STRs

Answer 7

• short tandem repeats
• length variation due to short repetitive sequences
• moderately polymorphic
• can be homozygous or heterozygous
• analyzed manually or automated
• uses PCR based technology

Question 8

Autosomal markers

Answer 8

• passed on in part, from all ancestors

- can distinguish between family members

Question 9

Mitochondrial markers

Answer 9

• a type of lineage marker

- passed on complete from mothers to sons/daughters

Question 10

Y-chromosome markers

Answer 10

• another type of lineage marker
• passed on complete from fathers to sons only
• Y-STR testing is very sensitive and can detect low levels of male DNA
• also allows for isolation of male component in male/female mixtures and deduce male/male mixtures