100. Which of the following marker proteins is NOT derived from cnidarians?
1. Green fluorescent protein
2. DSRED protein
3. Red fluorescent protein
4. Orange fluorescent protein

Correct Answer:

4. Orange fluorescent protein

Explanation:

Fluorescent proteins are often used as markers in molecular and cell biology. Here’s a breakdown of each protein:

1. Green Fluorescent Protein (GFP):
   GFP is derived from the jellyfish Aequorea victoria, making it a well-known cnidarian-derived marker.

2. DSRED Protein:
   DSRED is a red fluorescent protein derived from the coral species Discosoma. It is widely used for imaging purposes in cell biology.

3. Red Fluorescent Protein (RFP):
   RFP is also a fluorescent protein from coral species, specifically from the genus Discosoma, making it another cnidarian-derived marker.

4. Orange Fluorescent Protein (OFP):
   Unlike the others listed, OFP is derived from a species of coral but is not a typical cnidarian fluorescent protein. It is a mutant variant of the red fluorescent protein (RFP) but is sometimes used in systems where a different color is needed.

Conclusion:

The orange fluorescent protein (OFP) is not directly derived from cnidarians in the same sense as GFP, DSRED, or RFP. Although it is related to coral-derived proteins, it is a mutant of red fluorescent protein (RFP), making it the correct answer.

Correct Answer: 4. Orange fluorescent protein