mapping the genome

Question 1

what is a genome map?

Answer 1

diagram of the chromosome(s) showing the relative positions of key features
it is essential for investigating how the genome works and identifying disease genes and other regions of medical importance

Question 2

what are genetic maps? how is it generated?

Answer 2

show the relative positions of genes (or DNA sequence polymorphism) within the genome
generated by linkage analysis

Question 3

what is the logarithm of odds scores?

Answer 3

LOD scored provide a statistical estimate of whether 2 genes or DNA sequences are likely to be co-inherited and therefore located near each other on a chromosome

Question 4

what are physical maps?

Answer 4

involved direct examination of DNA by a range of techniques

it generates the complete genome sequence and measures distances in base-pairs

Question 5

what is called the proportion of progeny with recombinant phenotypes?

Answer 5

recombinant frequency

Question 6

how do you calculate the recombinant frequency?

Answer 6

RF=(recombinant offspring/total offspring)x100%
1%=1cM
1cM=1200kb

Question 7

what are DNA markers? what are the most informative genetic markers?

Answer 7

any piece of genomic DNA whose sequence is polymorphic

most SNPs

Question 8

what are SNPs? where can you find SNPs on average?

Answer 8

a particular nucleotide position in the genome which a variant in at least 1% of the population
SNPs can be seen every 300bp in the human genome sequence

Question 9

what do we call polymorphisms that create or destroy a recognition site for a particular restriction endonuclease?

Answer 9

restriction fragments length polymorphisms

Question 10

what is shotgun sequencing?

Answer 10

method where genomes are broken down into overlapping fragments (200-2000bp),then the overlapping regions are assembled by the computer to be able to physically map the human genome

Question 11

what is positional cloning?

Answer 11

method used to clone the genes for monogenic diseases such as cystic fibrosis and muscular dystrophy

Question 12

why would most genetic variation will not be associated with genetic diseases?

Answer 12

because variations that would cause diseases would be selected out across many generations and become rare

Question 13

what is linkage desiquilibrium?

Answer 13

when two loci/variants are linked non-randomly in a given population
even if 2 loci lie on different chromosomes, if the phenotype they code for confers a selective advantage, they will have a tendency to be inherited together, even if other alleles are segregated independently