Lecture 13: Forensics 1 File

Question 1

Explain ABO blood grouping in terms of alleles

Answer 1

h = null allele (produces no functional product)
A = synthesises A carbohydrate
B = synthesises B carbohydrate
h is recessive relative to A and B

Question 2

Is A or B dominant in ABO blood grouping ?

Answer 2

They are co-dominant (therfore if you have an A allele and a B allele you get blood group AB)

Question 3

What are SNP’s (single nucletide polymorphisms)

Answer 3

a difference in one nucleotide that creates variation (aggc > agcc)

Question 4

How do you genotype SNP’s ?

Answer 4

use array based technologies, primer extension based technologies and next gen sequencing

Question 5

What are Minisatallites (variable number tandem repeats VNTR’s) ?

Answer 5

10-100bp repeating unit, with 20 to 200 copies of the repeat

Question 6

What are microsatellites (short tandem repeats STR’s) ?

Answer 6

1-6bp repeating unit, with 5to 30 copies of the repeat

Question 7

What are STR’s used for ?

Answer 7

matching samples at a crime scene

Question 8

Human eye colour is linked to variation in which gene ?

Answer 8

OCA2

Question 9

What is the process for detecting fingerprints ?

Answer 9

1. prepare DNA fragments (use restriction enzyme)
2. run in gel electrophoresis
3. blot onto nylon membrane
4. hybridise with radioactive probe
5. autoradiography

Question 10

What are the pros of DNA fingerprinting ?

Answer 10

Highly informative, probes can be used on any species

Question 11

What are the cons of DNA fingerprinting ?

Answer 11

required large amounts of DNA (not amendable to PCR), banding patterns are complex (hard to compare gels)