Genetic Mapping

Question 1

What does it mean to “map a trait”

Answer 1

Identify the sequence variation that causes (single gene) or contributes (complex trait) to a trait
ONLY works if trait/disease is heritable

Question 2

What are the genetic markers used in genetic mapping

Answer 2

Single nucleotide polymorphisms (SNPs)

Question 3

What is the point of genetic mapping

Answer 3

Allows us to test for a mutation before phenotypes manifest
Responsible breeding
More insight into gene’s function(s)

Question 4

What is needed in order to map a trait

Answer 4

-Population with varying heritable trait(s)
-Samples from population (DNA, phenotypes, pedigree)
-Reference genome
-Set of known sequence variations within genome
-Money

Question 5

Alleles with tight linkage are ——– likely to be shuffled

Answer 5

Least

Question 6

Which is easier to map – selected or unselected traits

Answer 6

Selected

Question 7

What are the 4 ways to make a genetic map

Answer 7

Candidate gene screen
Linkage analysis
GWAS
Whole genome sequencing

Question 8

Pros/cons of candidate gene screen

Answer 8

-Cheap, fast, easy
-High risk of failure
-Look at genes that are known to cause disease in humans

Question 9

Pros/cons of linkage analysis

Answer 9

-Expensive, slow, labor-intensive
-Hard to collect family-based samples
-Moderate risk of failure
-Linkage may not be close to underlying gene
-Can use previously used microsatellites
Not very common

Question 10

Pros/cons of GWAS

Answer 10

-Faster than linkage
-Hard, moderate risk of failure
-Can get closer to mutation
The currently favoured method

Question 11

Pros/cons of whole genome sequencing

Answer 11

-Very expensive
-Becoming more popular
-Can detect all sequence variations

Question 12

Steps of genotyping on a commercial SNP array

Answer 12

-Amplify and fragment DNA
-Attach allele-specific oligo probes to each bead
-Add fragmented DNA
-Single base extensions with labelled nucleotides attach to complementary test DNA
-Read by scanner