bacteria on streptomycin

QUESTION

34) Strains Hfr Strs oroA-trpD+hisC+ and F- StrroroA+trpD-hisC- were allowed to conjugate. hisC+ exconjugates were selected by plating the mixture of bacteria on streptomycin minimal media lacking hi

34) Strains Hfr Strs oroA-trpD+hisC+ and F- StrroroA+trpD-hisC- were allowed to conjugate.  hisC+ exconjugates were selected by plating the mixture of bacteria on streptomycin minimal media lacking histidine.  1000 colonies were obtained and were replica plated to appropriate selective media. The number of colonies that appeared on each plate are shown in the table below.

genotype                   # colonies

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oroA+trpD+hisC+        20

oroA+trpD-hisC+        300

oroA-trpD+hisC+        580

oroA-trpD-hisC+        100

A) What is the order of these mutations? In the answer box, only type in the number of the correct option from the list below. For example, if you chose option 1, only type 1 into the box.

option 1: oroA trpD hisC

option 2: trpD oroA hisC

option 3: oroA hisC trpD

B) Calculate the distances between oroA and trpD, trpD and hisC, oroA and hisC. Report your answer in decimal form (no need to multiply by 100).

i. oroA..trpD =

ii. oroA..hisC =

iii. trpD..hisC =

35) You carry out a fluctuation test to determine the rate of spontaneous resistance to an antibiotic. You culture 20 tubes to a final concentration of 1×10^7 bacteria and plate the whole culture to media containing the antibiotic. Using the colony counts from the fluctuation analysis below, calculate the mutation rate. Notice that you will type the exponent value into the second box; do not type both values into one box and do not include “x10^” in either box. Please include a + or – to the beginning of the exponent value as needed, no space in between it and the number.

Number of colonies per plate      Number of plates with indicated colonies

0                                                                             13

1                                                                               5

2+                                                                              2

Answer for part 1:

x10^

Answer for part 2:

36) A single strand of DNA contains the sequence below.

5’-AACGTCATT-3’

A) Fill in the reverse complement of this sequence.

5′ –  ___ – ____ –  ___ –  ___ –  ___ –  ___ –  ___ –  ___ –  ___ – 3′

B) If the reverse complement is used as a template for transcription, what will the sequence of the mRNA be?

5′ –  ___ –  ___ –  ___ –  ___ –  ___ –  ___ –  ___ – ___ –  ___ – 3’

37) Match the LacZ and LacY expression levels under lactose induction to the following merodiploid genotypes:

a) Constitutive LacZ Constitutive LacY

b) No LacZ No LacY

c) Inducible LacZ Inducible LacY

d) Constitutive LacZ Inducible LacY

e) Inducible LacZ Constitutive LacY

f) None of these

I+P+O+Z-Y+ / I-dP+O+Z+Y-

I+P+O+Z+Y+ / I-P+OcZ-Y-

I+P+O+Z-Y+ / IsP+O+Z+Y-

I+P-O+Z+Y+ / I-P+O+Z+Y+

I+P+O+Z-Y- / I+P+O+Z+Y-