Chapter 4: Mapping Eukaryotes

Question 1

loci

Answer 1

gene position

Question 2

Recombination maps

Answer 2

assembled two or three genes at a time, with the use of a method called linkage analysis.

Question 3

What does linked gene mean?

Answer 3

The loci of those genes are on the same chromosome and, hence, the alleles on any one homo- log are physically joined (linked) by the DNA between them.

Question 4

Linked gene dihybrid cross ratio

Answer 4

1:1:1:1

Question 5

Syntenic

Answer 5

Genes on same chromosomes

Question 6

criteria for being a linked gene not taken from the results of a cross:

Answer 6

close enough to each other to disrupt independent assortment

Question 7

criteria for being a linked gene taken from the results of a cross: (2)

Answer 7

dihybrid test-cross results showing parental classes in excess of 50% and recombinant less than 50%

Question 8

what conformation:

Answer 8

Cis conformation (WT alleles on same homolog)

Question 9

What conformation:

Answer 9

Trans conformation (WT alleles on opposite homologs)

Question 10

Chiasmata+when does this occur?

Answer 10

The point of contact between the homologous pair of chromosomes, late prophase

Question 11

total gamete/phenotype formula:

Answer 11

2^n for n genes

Question 12

when calculating for recombinant frequency for genes farther apart, add the double cross over category…

Answer 12

twice

Question 13

Double cross over look like

Answer 13

parental

Question 14

calculating cross over interference (3):

Answer 14

1.find expected DCO by :

Gene: A C B

expected DCO freq= RF(a-c) X RF(B-C)

2. find the coefficient of coincidence (c): Obs DCO/ expect DCO
   For expected DCO: find by using DCO frequency X total offspring
3. Sub in interference formula:
   I= (1-c)X 100%

Question 15

How do you use the way that gives MORE MARKS U DUMBASS SO USE IT when solving for expected value? (4)

Answer 15

So in this type of question, you will be given two genes: AaBb or sm like that.

1. set up a 2x2 box with the two alleles ontop and on the side like a punnet square. add the amount of A, B, b, a showing up by adding the row/column.
2. Find frequency of each allele by dividing by the total.
3. Find the amount of one phenotype in the 4 boxes by multiplying two of the frequency together with the total amount of offspring.
4. Using that one box of expected filled out u can find the rest of the three by minus from the previous determined amount of A, B, b, a showing up by adding the row/column.

Question 16

expected phenotype ration for dihybrid test cross linked

Answer 16

P:R:R:P

Question 17

Trihybrid Testcross all linked expected ratio:

Answer 17

P:P:SCO:SCO:SCO:SCO:DCO:DCO

Question 18

Double strand break repair model of meiotic recombination summary and key points:

Answer 18

1. One sister chromatid breaks from Spo 11 in yeast
2. Endonuclease eats away from the 5’ end of broken dna
3. DNA thats broken is moved into the non sister chromatid (homologous one for crossing over) and new DNA is made using the unbroken DNA strand