TBR CBT 4 q 117

[pm1]

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In the passage they show a figure of the glycolytic pathway:

Then, the question follows:

117. The bond that is formed between the C-1 carbon of 1,3-bisphosphoglycerate and the phosphate group is BEST described as:

A. an ether linkage.
B. a mixed-acid anhydride linkage.
C. an ester linkage.
D. an amide.

Answer: B (highlight)

I thought it was C. Can someone please elaborate on this for me - I could not get much out of their explanation. I am not familiar with "mixed acid anhydride linkage reactions".

Thank you!

 

[N1st]

In the passage they show a figure of the glycolytic pathway:

Then, the question follows:

117. The bond that is formed between the C-1 carbon of 1,3-bisphosphoglycerate and the phosphate group is BEST described as:

A. an ether linkage.
B. a mixed-acid anhydride linkage.
C. an ester linkage.
D. an amide.

Answer: B (highlight)

I thought it was C. Can someone please elaborate on this for me - I could not get much out of their explanation. I am not familiar with "mixed acid anhydride linkage reactions".

Thank you!

An anhydride is a carbonyl bonded to an oxygen which is bonded to another carbonyl.

Phosphoanhydrides are the same but with phosphorus replacing the carbonyl carbon. In ATP, the bond between the alpha and beta, and the beta and gamma phosphates, are two phosphoanhydride bonds.

A "mixed" anhydride has O=C-O-Pi in it.

An ester is just one carbonyl bonded to the oxygen which is bonded to an alkane.

You don't need to know about reactions to answer this, it's just a nomenclature question.

 

[pm1]

An anhydride is a carbonyl bonded to an oxygen which is bonded to another carbonyl.

Phosphoanhydrides are the same but with phosphorus replacing the carbonyl carbon. In ATP, the bond between the alpha and beta, and the beta and gamma phosphates, are two phosphoanhydride bonds.

A "mixed" anhydride has O=C-O-Pi in it.

An ester is just one carbonyl bonded to the oxygen which is bonded to an alkane.

You don't need to know about reactions to answer this, it's just a nomenclature question.

thank you!
would you say that, in simplistic terms, anhydride is just taking a H2O away? Thus taking a H20 between Carboxylic acid and phosphoric acid?
Thanks!!

and one last thing, I know esters are COOR. So to confirm the R has to be a carbon chain?

 

[N1st]

thank you!
would you say that, in simplistic terms, anhydride is just taking a H2O away? Thus taking a H20 between Carboxylic acid and phosphoric acid?
Thanks!!

Yes that's right.

and one last thing, I know esters are COOR. So to confirm the R has to be a carbon chain?

The R has to be either an alkyl group or an aryl group, yes.