determining enzymes in a biosynthetic pathway

[plzNOCarribbean]

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Could find a previous thread specifically related to this, but I was wondering how you can determine the order of enzymes in a biosynthetic pathway, using that weird looking chart. I was never good at this, even when I took genetics lab and we had to do a chromatography experiment on it.

If someone could please explain to me the concept, and the reasoning behind how to solve it, w/ an example preferably, I would REALLY appreciate it! thanks. The chart is similar to the one on page 299 of the TBR bio book II.


I also have an example, which I found from my old lab.


A B C D E
1 X X X
2 X X
3 X X X X X
4 X
5 X X X X

The vertical axis is Compounds, and the Horizontal axis says Strains.

The question states, you are given the following results from a chromatography on several related strains. If you are told that the spots (X) represent compounds in the same biosynthetic pathway then:

A) what compound (1-5) is likely to be the final product?
B) which is likely the initial precursor
C) which strain (A-E) is likely to be the wild type

HOW DO YOU FIGURE THIS OUT ^

D) what is the order of the five compounds in the biosynthetic pathway?
Answer: 3 ==> 5 ==> 1 ==> 2 ==> 4

E) if we assume that each of the mutant strains have lost one enzyme in a biosynthetic pathway, SHOW WHICH MUTANTS ARE MISSING WHICH ENZYME.
Answer:
3 ==> 5 ==> 1 ==> 2 ==> 4
B D C E

Can someone explain to me what is going on. Is 3 the biochemical compound that is being created when there is a defect in strains A,B,C,D or E (ie these strains have a mutation in a gene that helps code for that enzyme)? Is that how we know it comes first, because if there was a mutation in each step of the pathway you still get compound 3, so it must be the initial precursor?

Sorry, I know that was winded but I really want to get this down. Thanks for the help

 

[apex954]

Could find a previous thread specifically related to this, but I was wondering how you can determine the order of enzymes in a biosynthetic pathway, using that weird looking chart. I was never good at this, even when I took genetics lab and we had to do a chromatography experiment on it.

If someone could please explain to me the concept, and the reasoning behind how to solve it, w/ an example preferably, I would REALLY appreciate it! thanks. The chart is similar to the one on page 299 of the TBR bio book II.


I also have an example, which I found from my old lab.


A B C D E
1 X X X
2 X X
3 X X X X X
4 X
5 X X X X

The vertical axis is Compounds, and the Horizontal axis says Strains.

The question states, you are given the following results from a chromatography on several related strains. If you are told that the spots (X) represent compounds in the same biosynthetic pathway then:

A) what compound (1-5) is likely to be the final product?
B) which is likely the initial precursor
C) which strain (A-E) is likely to be the wild type

HOW DO YOU FIGURE THIS OUT ^

D) what is the order of the five compounds in the biosynthetic pathway?
Answer: 3 ==> 5 ==> 1 ==> 2 ==> 4

E) if we assume that each of the mutant strains have lost one enzyme in a biosynthetic pathway, SHOW WHICH MUTANTS ARE MISSING WHICH ENZYME.
Answer:
3 ==> 5 ==> 1 ==> 2 ==> 4
B D C E

Can someone explain to me what is going on. Is 3 the biochemical compound that is being created when there is a defect in strains A,B,C,D or E (ie these strains have a mutation in a gene that helps code for that enzyme)? Is that how we know it comes first, because if there was a mutation in each step of the pathway you still get compound 3, so it must be the initial precursor?

Sorry, I know that was winded but I really want to get this down. Thanks for the help

Dont get lost in this kinda genetics details...plus as u said, d last time u saw this was in ur genetics lab....I dont see MCAT asking u this kinda of genetic specific questions, even BR bio didnt dive into d details, jus d general concept. well except if ur jus curious to have d understandin'

That being said, Im a not a geneticist, so i cant think of an example now besides the common trp.

Q1 the final product is 4

Q2 compound 3 is the initial precursor

Q3. strain A is the wild type

Q4 & 5 u've answered them urself

 

[BilalL]

Yes to determine the final product just look for the compd found only in 1 strain. The other strains would have a mutation in the pathway leading to a different final product. This also indicates the wild type strain.

The initial precursor will be found in all strains since it doesnt need an enzyme to be produced.

From this reasoning you can visualize the mutations along the pathway for the various strains.

 

[plzNOCarribbean]

Dont get lost in this kinda genetics details...plus as u said, d last time u saw this was in ur genetics lab....I dont see MCAT asking u this kinda of genetic specific questions, even BR bio didnt dive into d details, jus d general concept. well except if ur jus curious to have d understandin'

That being said, Im a not a geneticist, so i cant think of an example now besides the common trp.

Q1 the final product is 4

Q2 compound 3 is the initial precursor

Q3. strain A is the wild type

Q4 & 5 u've answered them urself

I'l have to respectfully disagree, for reasons I can say why....but I think you get the idea.