Assume that a mutation affects the gene for each of the following eukaryotic RNA polymerases. Match each mutation with the possible effects from the list provided. More than one effect is possible for each mutation.

RNA Polymerase Mutation       Effect(s)
RNA pol I                                  _______________
RNA pol II                                 _______________
RNA pol III                                _______________
snRNA                                      _______________

Ribosomal RNA is not processed.

Key Concepts

Eukaryotic RNA Polymerases

Eukaryotic cells contain three main types of RNA polymerases: RNA polymerase I (RNA pol I), RNA polymerase II (RNA pol II), and RNA polymerase III (RNA pol III). Each polymerase is responsible for transcribing different types of RNA. RNA pol I primarily synthesizes ribosomal RNA (rRNA), RNA pol II synthesizes messenger RNA (mRNA) and some small nuclear RNAs (snRNA), while RNA pol III synthesizes transfer RNA (tRNA) and other small RNAs. Understanding the specific functions of these polymerases is crucial for analyzing the effects of mutations.

Mutations and Their Effects

Mutations are changes in the DNA sequence that can affect gene function. Depending on the nature of the mutation, effects can range from benign to detrimental, potentially altering the protein produced or its regulatory mechanisms. In the context of RNA polymerases, mutations can lead to changes in transcription efficiency, fidelity, or the ability to recognize specific promoters, impacting overall gene expression and cellular function.

snRNA and Its Role

Small nuclear RNA (snRNA) plays a critical role in the splicing of pre-mRNA, a process essential for the maturation of mRNA before it is translated into protein. snRNAs are components of the spliceosome, the complex responsible for removing introns from pre-mRNA. Understanding the relationship between snRNA and RNA polymerase II is important, as mutations affecting RNA pol II can influence snRNA production and, consequently, mRNA processing.