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Nilanjan Bhowmick AIR 3, CSIR NET (Earth Science)
Kuldip Patle posted an Question
August 22, 2022 • 16:45 pm
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30 points
30 points
- CSIR NET
- Life Sciences
Three e. coli mutants were isolated which require compound 'a' for their growth. the compounds b, c and d are known to be involved in biosynthetic pathway to a.
Three E. coli mutants were isolated which require compound 'A' for their growth. The compounds B, C and D are known to be involved in biosynthetic pathway to A. In order to determine pathway, the mutants were grown in a minimal medium supplemented with ONE OF THE COMPOUNDS, A TO 112. D. The results obtained are summarized below: Mutant Medium supplemented with Compound B A D '+ = Growth on medium 0 = No growth Which of the following equation represent s the biosynthetic pathway of A? (1) BaC5D5A) (3) BODnCDA (2) COD0BOA (4) ADCODOB
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Nilanjana Sarkar![best-answer]()
In this case, it is mentioned 'A' is the product which is needed for growth of E. coli & its biosynthetic pathway involves B, C, D compounds. So, 'A' is the terminal product & medium supplemented by 'A' compound in all 3 mutants are showing growth. So, we can write in this way = _->_->_->A The medium with 'B' supplement in all 3 mutants are showing no growth. So, 'B' may be precursor. Because if precursor molecule is present but still is not converted into utilizable product, no growth will be observed. So, we can write = B->_->_->A Medium with 'D' supplement in 2 mutants (M2 & M3) are showing growth but M1 is not showing any growth. May be one mutation causes during formation of 'D' which makes it inviable. It is sure that it's before 'A'. Medium with 'C' supplement in only M3 is showing growth but in rest 2 (M1 & M2) are not showing growth. It is showing one more positive growth that compound 'B'. So compound 'C' should be after 'B' compound. So, we can write= B->C->_->A Compound 'D' supplementation is showing intermediate positive growth of 'A' & 'C' compounds supplementation. So, 'D' compound should be intermediate of 'C' & 'A' compounds. So, the pathway should be= B->C->D->A So, the right option 1. Here, I'm attaching a supported file for your reference. Hope it will beneficial for you. If you still have problem in this doubt, feel free to ask.
please suggest some little trick to tackle this question.
Easy trick for this type of questions where is asked the oder of components in biosynthetic pathway= Which one is more positive should be at last, which one is more negetive or zero should be at first position . And you have to arrange this on ascending order of positive growth. Like in this question B was zero, so B was at first or precursor. C was having one positive growth so it was placed as second intermediate. D was having 2 positive growth response, so D was placed at third position. A was having 3 positive growth, so A was the terminal product. Now you understood? Please let me know again
Here I'm attaching one more question from my own to make you understand the trick. Hope it will work. If you still have problem, feel free to ask.