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                                      _______________

Some pre-mRNA is not synthesized.

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 synthesizing different types of RNA; RNA pol I primarily synthesizes rRNA, RNA pol II synthesizes mRNA and some snRNA, and RNA pol III synthesizes tRNA and other small RNAs. Understanding the specific functions of these polymerases is crucial for analyzing the effects of mutations on gene expression.

Mutations and Their Effects

Mutations are changes in the DNA sequence that can affect gene function and expression. Depending on the type and location of the mutation, effects can range from no impact to complete loss of function. In the context of RNA polymerases, mutations can lead to insufficient synthesis of RNA, which may result in reduced levels of mRNA or other RNA types, ultimately affecting protein production and cellular function.

Pre-mRNA Synthesis

Pre-mRNA is the initial transcript synthesized from a DNA template before it undergoes processing to become mature mRNA. The synthesis of pre-mRNA is primarily the role of RNA polymerase II. If a mutation affects RNA pol II, it can lead to incomplete or absent pre-mRNA synthesis, which directly impacts the production of proteins necessary for various cellular functions, as indicated in the question.