markers and forensic genetics - lecture 18

Question 1

What is a genetic marker?

Answer 1

Some feature in the genome that allows us to differentiate between different alleles

Question 2

When are genetic markers useful?

Answer 2

• provide information on genetic differences between individuals
• measures diversity

Question 3

what are copy number variations?

Answer 3

Duplicated areas. Therefore the markers are difficult to detect

Question 4

what are the 4 markers we will be focusing on?

Answer 4

• RFLP(restriction fragment length polymorphism)
• SSLP ( simple sequence length polymorphism)
• SNP ( single nucleotide polymorphism)
• DNA sequencing

Question 5

What is the allozyme technique which was used before DNA technology?

Answer 5

• allelic variants of enzymes
• These enzymes differ in electric charge and migrate differently though the gel
• detected with a stain

Question 6

What are RFLPs?

Answer 6

Restriction fragment length polymorphisms

Question 7

How is the RFLP marker formed?

Answer 7

DNA cut into fragments by using restriction enzymes.

Question 8

How is RFLP a good marker?

Answer 8

The fragments differ in length due to the differences in the DNA repeats

Question 9

What does a VNTR stand for when using RFLP?

Answer 9

Variable Number of Tandem Repeats

Question 10

What are the two evolutionary traits that can be detected when using RFLPs?

Answer 10

• changes in number of VNTR units

- mutation in restriction site (no longer recognised by enzyme)

Question 11

When is RFLP used?

Answer 11

Crime scene forensics and paternity testing

Question 12

What does RADseq stand for?

Answer 12

‘Reduced representation sequencing’

Question 13

How does RADseq work?

Answer 13

• Use restriction enzymes to get out a piece of DNA sequence
• Sequence
• sequence the individuals and compare

Question 14

How are ‘simple sequence repeats’ good markers?

Answer 14

Highly polymorphic (highly variable) – reflects very high mutation rates
• Can distinguish many alleles at a locus
- Amplify the region using PCR

Question 15

What are SNP markers?

Answer 15

• single base differences between alleles at genomic location

Question 16

How to identify SNP markers?

Answer 16

Sequence the region

Question 17

what is a haplotype?

Answer 17

A small chromosomal block that is inherited

Question 18

what is a genealogy

Answer 18

a line of descent traced from an ancestor

Question 19

What do SNPs do in a genealogy?

Answer 19

differentiate in the genealogy due to haplotypes

Question 20

What are 3 reasons that mitochondrial markers are important?

Answer 20

• no recombination , so each sequence represents the end point of a lineage
• haploid
• sequences are highly variable

Question 21

Where can genetic markers been seen to be used prevalently?

Answer 21

• chilean sea bass ( Dissostichus eleginodies)
• Red snapper ( lutjanus campechanus)
• pacific red snapper
• whale meat in Japan

Question 22

Problems with chilean sae bass after genetic research?

Answer 22

8% are another species, 15% has forge in haplotypes.

Question 23

Problems with red snapper?

Answer 23

77% of samples in USA were not actually , genetically red snapper

Question 24

problems with whale meat in Japan?

Answer 24

• some gray whale killed ( very endangered)
• found eight species: baleen whales, sperm whales, beaked whales, killer whales, dolphins, porpoises, plus sheep and horses.

Question 25

problems with pacific red snapper?

Answer 25

mitochondrial markers determined that 56% are actually species listed as being overfished

Question 26

Why can RFLP work?

Answer 26

Each person has a different length of Variable Number Tandem Repeats

Question 27

How can RADseq help identify mutations?

Answer 27

Should also identify mutations in cut sites by the absence of a sequence