Final answer:
A nucleic acid found in the cytosol of a eukaryotic cell is typically RNA. In an experiment similar to Nirenberg and Matthaei, using synthetic RNA with only cytosine would produce a polypeptide chain of the amino acid proline because the codon CCC codes for proline.
Step-by-step explanation:
If you found a nucleic acid in the cytosol of a eukaryotic cell, it is likely to be ribonucleic acid (RNA). In eukaryotic cells, RNA is the nucleic acid that is responsible for carrying the information from DNA in the nucleus to a ribosome in the cytoplasm, where protein synthesis occurs. This is because DNA is confined to the nucleus, and the process of transferring genetic information involves transcription of DNA into mRNA, which then travels out of the nucleus to the cytoplasm to be translated into proteins.
The experiment you described is akin to that performed by Nirenberg and Matthaei, which would involve the synthesis of polypeptides in response to the synthetic RNA added. If synthetic RNA containing only the base cytosine was added to bacterial contents, a polypeptide chain of repeated proline amino acids would be created. This is because in the genetic code, the codon CCC (cystosine-cytosine-cytosine) codes for the amino acid proline. Therefore, a synthetic RNA containing only cytosine bases would translate into a polypeptide consisting entirely of proline amino acids due to the redundancy and triplet nature of the genetic code.