Linkage Analysis

Question 1

linkage analysis

Answer 1

find out if 2 genes are linked , meaning they always travel together generations. like red hair, fairskin and freckles

Question 2

what is association analyiss

Answer 2

it studies the increased or decreased frequency of a particular allele or set of alleles in a population

Question 3

how is linkage analysis studied

Answer 3

in families

Question 4

how is association analysis studied

Answer 4

in populations

Question 5

what 2 things has meisos undergone to create diverisity

Answer 5

recombination and random assortment

Question 6

what was mendels first law

Answer 6

law of segregation of genes. - everyone has 2 alleles that control 1 trait , and one allele is inherited from each parent .

these alleles segregate during meisos so that each gamete only gets 1 allele

Question 7

what was mendels second law

Answer 7

the law of independent assortment = alleles for separate traits are passed independently of each other

Question 8

how is linkage a violation of mendels laws

Answer 8

it is a violation because based on the law of independent assortment, alleles should be separating independently from each other, but in this case the genes are linked and now separating independently

Question 9

if there is no crossover does recombination occur

Answer 9

no , there is no mixing of DNA

Question 10

If there is a single crossover or x2 does recombination occur

Answer 10

yes

Question 11

what is the mechanism behind linked genes

Answer 11

the 2 genes are so close together, that there is not enough space for a crossover to occur

Question 12

the closer the genes the more or less likeley for a crossover to occur

Answer 12

less

Question 13

what determines whether a crossover is possible or not

Answer 13

the distance beteen the 2 genes

Question 14

the smaller the __________ the closer the 2 loci are

Answer 14

recombination frequency

Question 15

how is recombination frequency calculated

Answer 15

it is a proportion (NOT a %).

theta 0 = no recombination

theta 0.5 = independent assortment (recombination occurs)

Question 16

what are the 2 key peieces of information that we need to detect a recombination event

Answer 16

Looking @ 1 gene

1. the alleles at a locus need to be heterozygous
2. the phase of the alleles of the 2 loci must be known (cis or trans)

Question 17

how do you know if the alleles are cis or trans

Answer 17

Looking @ 2 genes on a chromosome arm

cis = both of the alleles on the same chromosome arm are both recessive or both dom

trans = one dom and the other recessive

Question 18

linkage analysis depends on

Answer 18

the frequency of recombination

Question 19

information from linkage is used to …

Answer 19

it is used to develop genetic maps in humans

Question 20

what does map distance mean

Answer 20

the genetic length over which on avg one crossover occurs in 1% of meiosoise s

Question 21

how are genetic maps measured

Answer 21

in centimorgans

Question 22

what does linkage equilibrium mean

Answer 22

the frequency of each allele within the haplotypes is the same as the frequency of that allele in the population as a whole.

basically the linkage of a specfic family matches what you expect it to be for the entire population

Question 23

what is linkage disquilibrium

Answer 23

when the gene linkage ratio for a specific family does not match your value for the population

Question 24

what 3 things are needed for linkage analysis

Answer 24

heterozygous
homozygous recesv
generate a large # of offspring

Question 25

LOD score

Answer 25

a study to see if 2 genes on the same chromosome are linked

Question 26

the LOD score gives what 2 things

Answer 26

best estimate of the recombination frequency

theta max = recombination frequency

an assessment of how strong the evidence is for linkage at the value of theta max

Question 27

is the LOD score is more than 3 what does that say about gene linkage

Answer 27

> 3 = genes are linked

Question 28

if the LOD score is less than 3 what does that tell you

Answer 28

the genes are not linked

Question 29

A-3
B-1
C-5
D-2

Which of these genes are linked

Answer 29

C because 3+

A bcause 3+

Question 30

what factors affect linkage analysis

Answer 30

genetic/ locus heterogeneity

Question 31

what does complex traits mean

Answer 31

the traits that do not follow the mendelian inheritance laws

Question 32

what is gene mapping

Answer 32

take a sequence of DNA and map the genes