Flashcards in Genetics 3 Deck (31):
What is disease mapping dependent on?
genetic marker maps
How many markers are required for 10-20cM spacing ?
Which generation is more informative for disease mapping?
What are genetic markers?
a gene or DNA sequence with a known location on a chromosome that can be used to identify individuals or species. It can be described as a variation (which may arise due to mutation or alteration in the genomic loci) that can be observed
How can a disease map be analyzed with markers?
easily analyzed with PCR or hybridization
How can the Chromosomal location be determined with markers?
hybrid panels are genome search
What are first generation DNA markers and why aren't they sufficient?
They are restriction fragment length polymorphism(RFLPs)
they only give low information content (two alleles)
What are the second generation markers?
single nucleotide polymorphism (SNPs)
What are minisatelites?
Numerous alleles (9-65 bp repeats) with high heterozygosity
how are minisatelites detected minisatelites?
detection by southern blotting (disadvantage
uneven distribution is a disadvantage
What are microsatelites?
large number of Di, tri, tetra nucleotide tandem repeats
they are the markers of choice
How are microsatelites detected?
PCR (multiplex flouresence)
What are single nucleotide polymorphism (SNPs)?
large number every 10Kb that are closely spaced
automation allows high throughput
What is the first step in gene mapping?
What is the second step in gene mapping?
typing with informative markers
What is the third step in gene mapping?
determine te recombination fraction
When are the marker and the disease not linked?
When there is a high recombination fraction
If the recombination is significantly less than 0.5 loci are linked
What will the recombination fraction never be higher than?
because there is a 50% chance that a gene will cross or not cross
If the recombinants cannot be calculated then what can be calculated?
the likelihood that thy are linked
What are can be assumed when calculating the likelihood of linked genes?
loci are linked recombination fraction = theta
not linked recombination fraction = 0.5
What are LOD scores?
logarithm of odds
How do determine the LOD?
calculate the odds and divide by 0.5
take the log of that number and that your LOD score
What has the maximum LOD?
most likely recombination fraction
What is the likelihood of odds a function of?
Why are LOD scores calculated?
for a range of theta
What are figuring when calculating LOD?
likelihood of linkage or no linkage
What does a LOD score has to say it is for sure linkage?
any number greater than or equal positive 3
any number less than positive 3 there some question or no linkage
How do you determine if the gene is linked to a particular marker?
Begin with marker framework
place disease gene in marker interval using algorithms
Curve of lod is obtained
highest peak is likely location
What is positional cloning?
Cloning of gene based on position on chromosome without knowing the function
What was the first gene identified by positional cloning?