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.

Some pre-mRNA is not synthesized.

Verified step by step guidance

1. Understand the role of each RNA polymerase in eukaryotic transcription: RNA polymerase I synthesizes rRNA (except 5S rRNA), RNA polymerase II synthesizes pre-mRNA (precursor to mRNA), and RNA polymerase III synthesizes tRNA and 5S rRNA. Additionally, snRNA (small nuclear RNA) is involved in splicing and is primarily transcribed by RNA polymerase II and III.
2. Analyze the mutation effects: The problem states that 'some pre-mRNA is not synthesized.' This indicates a disruption in the function of RNA polymerase II, as it is responsible for synthesizing pre-mRNA.
3. Match RNA polymerase I with its potential effects: A mutation in RNA polymerase I would primarily affect the synthesis of rRNA, which is crucial for ribosome assembly and protein synthesis.
4. Match RNA polymerase III with its potential effects: A mutation in RNA polymerase III would disrupt the synthesis of tRNA and 5S rRNA, which are essential for translation and ribosome function.
5. Match snRNA with its potential effects: Since snRNA is involved in splicing, a mutation affecting its transcription (by RNA polymerase II or III) could lead to defects in mRNA processing, resulting in improperly spliced mRNA.

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 synthesizes ribosomal RNA (rRNA), RNA pol II synthesizes messenger RNA (mRNA) and some small nuclear RNAs (snRNA), and 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 type and location of the mutation, the effects can range from benign to detrimental, potentially leading to the loss of function of the gene product. In the context of RNA polymerases, mutations can disrupt the synthesis of specific RNA types, leading to various cellular consequences, such as impaired protein synthesis or altered gene expression.

Pre-mRNA Synthesis

Pre-mRNA is the initial transcript synthesized from DNA before it undergoes processing to become mature mRNA. This process is primarily facilitated by RNA pol II. If a mutation affects RNA pol II, it can lead to insufficient or absent pre-mRNA synthesis, which directly impacts the production of proteins necessary for cellular function. Understanding the relationship between RNA polymerase activity and pre-mRNA synthesis is essential for predicting the outcomes of mutations.