× Didn't find what you were looking for? Ask a question
Top Posters
Since Sunday
c
5
j
5
a
5
L
5
f
5
j
5
D
4
k
4
y
4
t
4
h
4
l
4
New Topic  
tee tee
wrote...
Donated
Posts: 63
Rep: 8 0
12 years ago
Could someone please help me with these questions asap. I am willing to donate. Wink Face

Question 1.
An experiment was carried out in E. coli mapping five genes around the chromosome with each of three different Hfr strains.  The genetic markers were bio, met, phe, his, and trp.  The Hfr strains were found to transfer the genetic markers at the times indicated below.  Construct a genetic map of the E. coli chromosome that includes all five markers, the genetic distances in minutes between adjacent gene pairs, and the origin and direction of transfer of each Hfr.  Complete the missing data in the table indicated by the question marks.

   Hfrl markers   bio   met   phe   his
   Time of entry      26   44   66   ?

   Hfr2 markers      phe   met   bio   trp
   Time of entry      ?   26   44   75

   Hfr3 markers      phe   his   ?   bio
   Time of entry      6   27   35   ?

Question 2.
Bacteriophage Pl was grown on a wild type strain of E. coli and the resulting progeny phage are used to infect a strain with three mutations, arg-, pro-, his-, each of which results in a requirement for an amino acid, either arginine, proline, or histidine, respectively.  Equal volumes of the infected culture were spread on plates containing minimal medium supplemented with various combinations of the amino acids, and the number of colonies appearing on each plate was counted.  The results are shown below.  Note - in each row, the + signs indicate the amino acid is present in the media.

Supplements
-------------------------------------------------
   Plate number   Arginine   Proline   Histidine   Number of colonies
   1   +   +      0   1000
   2   +   0      +   1000
   3   0   +      +   1000
   4   +   0      0   200
   5   0   +      0   100
   6   0   0      +   0

(a)   For each of the six types of medium, list the donor markers that must be present to allow the transduced cell to form colonies.
(b)   Using these results, construct a genetic map of the arg, pro, his region showing the relative order of the genes and the cotransduction frequencies between the markers.


Question 3.
A cotransduction study involving five bacterial loci, a, b, c, d, and e, is carried out. Transductants are initially selected on the basis of the a gene. The frequency with which each of the other four genes is cotransduced with a is as follows: a with b, 47%; a with c, 56%; a with d, 63%; and a with e, 64%.

(a)   Based on a quick inspection of these cotransdcution frequencies what general statement can be made about the degree of linkage between these loci?
(b)   Assuming the differences in these cotransduction frequencies to be statistically significant, what do they suggest about the order of these five loci?
(c)   The relative positions of two of these loci cannot be reliably stated. Identify these two loci and explain why their positions cannot be stated reliably.
(d)   Can you suggest how you might go about determining the order of these two loci?
Read 5204 times
8 Replies

Related Topics

Replies
wrote...
12 years ago
Question 3.
A cotransduction study involving five bacterial loci, a, b, c, d, and e, is carried out. Transductants are initially selected on the basis of the a gene. The frequency with which each of the other four genes is cotransduced with a is as follows: a with b, 47%; a with c, 56%; a with d, 63%; and a with e, 64%.

(a)   Based on a quick inspection of these cotransdcution frequencies what general statement can be made about the degree of linkage between these loci?
(b)   Assuming the differences in these cotransduction frequencies to be statistically significant, what do they suggest about the order of these five loci?
(c)   The relative positions of two of these loci cannot be reliably stated. Identify these two loci and explain why their positions cannot be stated reliably.
(d)   Can you suggest how you might go about determining the order of these two loci?

3(a) Closely linked.

3(b) Order is a-e-d-c-b.

3(c) The relative position of E and D can't be reliably stated because their distance is 1%. That degree of linkage is really close that D may come before E during cotransduction.

3(d) Conduct a gene mapping experiment where their distance with respect to "a" will be measured.

Quote
Question 2.
Bacteriophage Pl was grown on a wild type strain of E. coli and the resulting progeny phage are used to infect a strain with three mutations, arg-, pro-, his-, each of which results in a requirement for an amino acid, either arginine, proline, or histidine, respectively.  Equal volumes of the infected culture were spread on plates containing minimal medium supplemented with various combinations of the amino acids, and the number of colonies appearing on each plate was counted.  The results are shown below.  Note - in each row, the + signs indicate the amino acid is present in the media.

Supplements
-------------------------------------------------
   Plate number   Arginine   Proline   Histidine   Number of colonies
   1   +   +      0   1000
   2   +   0      +   1000
   3   0   +      +   1000
   4   +   0      0   200
   5   0   +      0   100
   6   0   0      +   0

(a)   For each of the six types of medium, list the donor markers that must be present to allow the transduced cell to form colonies.
(b)   Using these results, construct a genetic map of the arg, pro, his region showing the relative order of the genes and the cotransduction frequencies between the markers.

For question 2(b), I got a circle map with arginine on top, histidine at bottom right, and proline at bottom left - I didn't know how to calculate the cotransduction frequencies.

For 2(a), I got 1st- his+, 2nd- pro+, 3rd- arg+, 4th- pro+ his+, 5th- arg+,his+, 6th- arg+ pro+
could of, should of, would of...
tee Author
wrote...
Donated
12 years ago
Thank you verry much! Wink Face
wrote...
Staff Member
12 years ago
Thank you verry much! Wink Face

What did you end up doing for question 1?
- Master of Science in Biology
- Bachelor of Science
tee Author
wrote...
Donated
12 years ago
I have not done it yet, I'm just reading the book and trying to work it out.

If I get it done ill post the answer. Wink Face
tee Author
wrote...
Donated
12 years ago
What did you end up doing for question 1?

Question 1 I Got

his- 87
phe- 4
35- Trp
bio- 66

dose that sound right?
tee Author
wrote...
Donated
12 years ago
I have all the Answers. if anybody needs them let me know and ill help you!! Wink Face
wrote...
12 years ago
@tee, Would you be able to send me the answers for questions 2 and 3?
tee Author
wrote...
Donated
12 years ago
@tee, Would you be able to send me the answers for questions 2 and 3?

Become a contributing  member and I will be able to help you Wink Face
New Topic      
Explore
Post your homework questions and get free online help from our incredible volunteers
  927 People Browsing
 127 Signed Up Today
Related Images
  
 1457
  
 419
  
 248
Your Opinion
Who will win the 2024 president election?
Votes: 8
Closes: November 4