Textbook Question
Assuming that each nucleotide in an mRNA is 0.34 nm long, how many triplet codes can simultaneously occupy the space in a ribosome that is 20 nm in diameter?
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11. Translation
Translation
2:46 minutesProblem 15c
Textbook Question
The three major forms of RNA (mRNA, tRNA, and rRNA) interact during translation.
Which form of RNA is least stable in eukaryotes? Why is this form least stable?
Verified step by step guidance1
Understand the three major forms of RNA: mRNA (messenger RNA), tRNA (transfer RNA), and rRNA (ribosomal RNA). Each plays a distinct role in translation. mRNA carries the genetic code from DNA to the ribosome, tRNA brings amino acids to the ribosome, and rRNA forms the structural and functional components of the ribosome.
Recognize that stability in RNA molecules is influenced by their structure and function. rRNA and tRNA are highly structured and often form stable secondary and tertiary structures, which protect them from degradation.
Note that mRNA is the least stable form of RNA in eukaryotes. This is because mRNA is designed to be transient, allowing for the regulation of gene expression. Once its message is translated into protein, it is no longer needed and is rapidly degraded.
Understand the mechanisms of mRNA degradation. In eukaryotes, mRNA is degraded through processes such as deadenylation (removal of the poly-A tail), decapping (removal of the 5' cap), and exonucleolytic decay. These processes ensure that mRNA does not persist longer than necessary.
Conclude that the least stability of mRNA is an evolutionary adaptation to allow cells to quickly respond to changes in their environment by regulating protein synthesis efficiently.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Types of RNA
There are three major types of RNA involved in protein synthesis: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). mRNA carries the genetic information from DNA to the ribosome, tRNA transports amino acids to the ribosome for protein assembly, and rRNA is a structural component of ribosomes, facilitating the translation process.
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Stability of RNA
RNA stability refers to the lifespan of RNA molecules within a cell. mRNA is generally less stable than rRNA and tRNA due to its role in conveying transient genetic information, which requires it to be rapidly synthesized and degraded. This instability allows for precise regulation of gene expression in response to cellular needs.
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Eukaryotic mRNA Processing
In eukaryotes, mRNA undergoes extensive processing, including capping, polyadenylation, and splicing, before it can be translated. These modifications enhance mRNA stability and translation efficiency, but the inherent design of mRNA, which is meant to be temporary, contributes to its overall lower stability compared to tRNA and rRNA, which have more stable structures.
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