MCAT Biology : Nucleus and Nucleolus
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Example Question #251 : Cell Biology, Molecular Biology, And Genetics
Which of the following is true of the RNA transcripts in the nucleolus and nucleus?
Translation of nuclear transcripts occurs in the nucleoplasm, whereas translation of nucleolar transcripts occurs in the cytoplasm
Translation of nuclear transcripts occurs in the cytoplasm, whereas translation of nucleolar transcripts occurs in nucleoplasm
None of these are true
Translation of both transcripts occurs in the cytoplasm
None of these are true
In the nucleolus, the transcripts synthesized are rRNA molecules. The unique aspect of rRNA molecules is that they are never converted to proteins; therefore, they never undergo translation. The rRNA molecules synthesized by the nucleolus are assembled with other proteins to create ribosomes; they themselves never undergo translation.
Transcription in the rest of the nucleus produces mRNA molecules that enter the cytoplasm and undergo translation to create proteins.
Example Question #1292 : Biology
The nucleolus is responsible for synthesis of which of the following compounds?
None of these
Arachidonic acid
tRNA
rRNA
DNA
rRNA
The nucleolus has genes for transcribing ribosomal RNA. RNA polymerase I in the nucleolus transcribes the gene for ribosomal RNA and causes formation of ribosomal complexes. mRNA and tRNA are transcribed elsewhere in the nucleus and use RNA polymerase II and III, respectively. Arachidonic acid is an omega-6 polyunsaturated fatty acid, which plays roles in cell-signaling, prostaglandin synthesis, and the immune response, and is synthesized in the cytosol.
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