Question

Which of the following is not a general function of an ncRNA? a. encoding a polypeptide b. acting as a ribozyme c. acting as a guide d. acting as a scaffold e. acting as a decoy

Short answer

The correct answer is option a) 'encoding a polypeptide'. This is not a general function of an ncRNA.

Step-by-step solution

- Understanding The Functions of an ncRNA

Non-coding RNAs (ncRNAs) are types of RNA that do not encode for protein sequences. Some of the well-known functions of ncRNA include, but are not limited to, acting as a ribozyme, acting as a guide, acting as a scaffold and acting as a decoy. The ribozyme function allows for rRNA to be involved in protein synthesis. In its role as a guide, ncRNA directs modifications to other RNAs. As a scaffold, ncRNA can provide structure for ribonuclear proteins complexes. In its decoy function, ncRNA can bind and sequester proteins or RNAs. Therefore, any choice depicting an ncRNA encoding a protein sequence does not pertain to the general functions of an ncRNA.

- Identifying The Incorrect Option

Referring back to the question, the exercise now becomes finding the option that indicates an ncRNA encoding a protein sequence. In the given options a) through e), the only option that suggests that an ncRNA encodes a protein is option a) 'encoding a polypeptide'.

- Conclusion

Based on the understanding of ncRNA, it is inferred that ncRNA cannot encode a protein sequence. Therefore, the correct answer is option a) 'encoding a polypeptide' is not a general function of an ncRNA.

Key concepts

ncRNA functions

Non-coding RNAs, or ncRNAs, are a fascinating and essential part of genetics that perform various functions within cells without encoding proteins. Unlike messenger RNA (mRNA), they don’t transform into proteins, but instead have unique roles.

• They act as guides to facilitate specific chemical modifications among ribonucleic acids, helping direct these molecules to precise targets in the cell.


• ncRNAs function as scaffolds by providing a structural framework. This helps maintain the integrity and formation of ribonuclear protein complexes, combining RNA and proteins in proper arrangements.


• As decoys, they act like traps, binding to certain molecules to regulate cellular activity by sequestering proteins, ensuring that interactions occur in a controlled manner.


• Notably, when they function as ribozymes, they become catalysts, influencing biochemical reactions. This ability showcases their versatility beyond mere genetic information carriers.

However, encoding a polypeptide is not one of their recognized roles, distinguishing them from protein-coding RNAs.

ribozyme

Ribozymes are unique RNA molecules with enzymatic activity, a rare feature usually associated with proteins. This particular function of ncRNA is pivotal in energy transfer and molecular synthesis within cells. Acting as catalysts, ribozymes facilitate essential biochemical reactions without being consumed in the process. An excellent example of a ribozyme at work can be observed in the ribosome during protein synthesis. Here, ribosomal RNA catalyzes the formation of peptide bonds, effectively stitching amino acids together to form proteins.
Because of their specificity, ribozymes can greatly enhance the rate of chemical reactions, often making them indispensable in essential cellular processes. Their ability to perform complex catalysis without the need for protein involvement highlights the intricate functionality of ncRNAs.

RNA proteins

In the realm of molecular biology, the partnership between RNA and proteins is crucial. In many cellular processes, RNA does not work alone but teams up with proteins to perform its functions. The combination of RNA and proteins forms what are known as ribonucleoproteins (RNPs). These complexes are essential in various cellular processes such as transcription, translation, and RNA processing.

• RNPs can guide, protect, and structure RNA molecules, rendering them more stable and functional.


• Through scaffolding, RNA provides a supportive architecture, allowing proteins to assemble in precise configurations required for their activity.


• Furthermore, these complexes sometimes modulate the activity of RNA molecules, expanding the functional repertoire of RNAs in the cell.

Such intricate interactions exemplify the elegant orchestration between RNA and proteins in maintaining cellular homeostasis.

molecular biology

Molecular biology involves studying the role, structure, and interactions of molecules that keep the cellular machinery active. This field focuses on understanding how various cellular processes are governed by RNA, DNA, and proteins. In molecular biology, RNA holds a central role. Beyond just serving as a messenger between DNA and proteins, RNA contributes to regulation and catalysis. Some fundamental processes where RNA is critical involve its transformation into functional machinery through transcription or translation.

• During transcription, RNA is synthesized from a DNA template, a crucial step for gene expression.


• Transcription might produce mRNA for protein coding, or ncRNAs contributing to cellular regulation and structural roles.

By diving into these processes, molecular biology attempts to unravel the complexities of life's blueprint, illustrating how millions of molecules interact harmoniously to sustain life.