Question about Prosthetic Groups

[ArchieMoses]

from the tpr science wkbk (pg. 41 if you want to see the exact question i'm looking at):

Which of the following statements about prosthetic groups are true?

I. They are non-protein organic molecules.

II. They are added to proteins after translation.

III. They are needed in order for some enzymes to catalyze reactions.
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According to the book, all 3 are correct, but I didn't like their explanation.

I figured II, and III were right, but I missed it because I was unsure about I.

According to the diagrams in the passage, prosthetic groups seem to be attached to 1 amino acid, and I was unsure if 1 amino acid was enough to qualify as a protein...which I'm now realizing it isn't. Would you consider 2 linked amino acids a protein then? Its these little things that always get me

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[artaxerxes]

from the tpr science wkbk (pg. 41 if you want to see the exact question i'm looking at):

Which of the following statements about prosthetic groups are true?

I. They are non-protein organic molecules.

II. They are added to proteins after translation.

III. They are needed in order for some enzymes to catalyze reactions.
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According to the book, all 3 are correct, but I didn't like their explanation.

I figured II, and III were right, but I missed it because I was unsure about I.

According to the diagrams in the passage, prosthetic groups seem to be attached to 1 amino acid, and I was unsure if 1 amino acid was enough to qualify as a protein...which I'm now realizing it isn't. Would you consider 2 linked amino acids a protein then? Its these little things that always get me

The biggest problem I have with this question is I-non-protein organic molecules, some groups are not orgnaic, for example I think Mg2+ or Zn are prosthetic groups in some enzymes.

In regards the proteins though.... 1 amino acid is an amino acid, 2 linked by peptide bond is a peptide, but a not a protein. Protein generally refer to things that are large polypeptides hundreds of peptide bonds and up.

 

[ArchieMoses]

The biggest problem I have with this question is I-non-protein organic molecules, some groups are not orgnaic, for example I think Mg2+ or Zn are prosthetic groups in some enzymes.

In regards the proteins though.... 1 amino acid is an amino acid, 2 linked by peptide bond is a peptide, but a not a protein. Protein generally refer to things that are large polypeptides hundreds of peptide bonds and up.

ah ok, thanks for clearing that up. That first part was confusing.

 

[Surf Rx]

Prosthetic groups can be organic or inorganic. The question asks which of the statements are true. So answer choice I is acceptable because it is true in certain cases.

 

[quiksilver87]

Prosthetic groups can be organic or inorganic. The question asks which of the statements are true. So answer choice I is acceptable because it is true in certain cases.

that is true...prosthetic groups can be organic...and some inorganic
Thus, you cant really answer this question.

 

[Green Pirate]

that is true...prosthetic groups can be organic...and some inorganic
Thus, you cant really answer this question.

yeah. the way statement I is stated, it seems to be suggesting that all prosthetic groups are organic, which they obviously are not. It's really poorly worded, because I can also see how someone might interpret it to mean that "they are organic, but can also be inorganic."