Exam 1: Lecture 14

Question 1

define haplotype

Answer 1

set of DNA variations, or polymorphisms, that tend to be inherited together

in cis w/ each other; linked and come together as a haplotype. tend to stick around in a family/population

Question 2

loci are in linkage disequilibrium when:

Answer 2

the frequency of association of their different alleles is higher/lower than what would be expected if the loci where independent and associated randomly

Question 3

t/f: different haplotypes are associated with milder of more severe forms of sickle-cell anemia

Answer 3

true

Question 4

genetic map is based on:

Answer 4

based on recombination btwn genes on same chromosome; generated for model organisms (fruit flies were the workhorse)

Question 5

physical map is based on:

Answer 5

actual nucleotide position on a chromosome where a gene exists

Question 6

physical map may have genes closer of further apart bc (vs a genetic map)

Answer 6

recombination is different in that part of the chromosome; parts of our chromosomes have recombination hotspots

Question 7

cM is a unit for measuring

Answer 7

genetic linkage

Question 8

somatic-cell hybridization can be used to determine

Answer 8

which chromosome contains a gene of interest (ex human and mouse cells)

Question 9

if the gene product is present in a cell line with an intact chromosome, but missing from a line with a chromosome deletion, the gene for that product must be located

Answer 9

in the deleted region

Question 10

t/f: somatic-cell hybridization is used to assign a gene to a particular human chromosome

Answer 10

true

Question 11

somatic-cell hybridization is physical or genetic mapping?

Answer 11

physical mapping

Question 12

making radiation hybrids by irradiation with x-rays is useful for

Answer 12

a physical mapping approach based on radiation-induced deletions for mapping markers

Question 13

deletion mapping can be used to

Answer 13

determine the chromosome location of a gene

Question 14

homozygous for a recessive mutation in a gene of interest is crossed with an individual heterozygous for a deletion:

Answer 14

if the gene of interest is in the deletion region, half of the progeny will display the mutant phenotype

if the gene is not w/in the deletion region, all of the progeny will be wild type

Question 15

in situ hybridization is another technique for

Answer 15

determining the chromosomal location of a gene (FISH)

Question 16

briefly, the technique behind FISH

Answer 16

dna probe w/complimentary to known segment of dna has fluorescent dye and then hybridizes to interphase/metaphase cells

Question 17

FISH is useful for

Answer 17

• detect small regions of deletions/duplications
• examine specific regions of the genome in non-dividing cells
• to map genes

Question 18

levels of recombination vary widely among:

Answer 18

• species
• chromosomes of a single species
• btwn males and females

Question 19

why is it beneficial that humans have high recombination rates?

Answer 19

evolution benefits, variation, diversity, adaptation

Question 20

genome-wide association studies (GWAS) examines

Answer 20

genetic (sequence) variants across the entire genome to find those that are associated with a trait or disease
each indiv differs by millions of sequence variants scattered across the genome

Question 21

pros of GWAS

Answer 21

• identifies variants that are in higher proportion in the study group
• understand genetic basis of all human disease

Question 22

cons of GWAS

Answer 22

• need lrg cohort
• need to establish biological relevance w/ variants
• variants associated with a trait often occur in noncoding parts of the genome (introns)