Ribosomal RNA and its Role in Protein Synthesis

Ribosomal RNA (rRNA) is crucial for protein synthesis, forming the structural and functional core of ribosomes. It aligns mRNA and tRNA for accurate decoding, catalyzes peptide bonds, and is used in phylogenetic analysis. The 16S rRNA, in particular, is essential for prokaryotic translation initiation and evolutionary studies. Unlike mRNA and tRNA, rRNA is stable and integral to the ribosome's assembly, playing a key role in the translation process and the central dogma of molecular biology.

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The Essential Functions of Ribosomal RNA in Protein Synthesis

Ribosomal RNA (rRNA) is a key molecular component of ribosomes, the cellular machines that orchestrate the synthesis of proteins. In prokaryotes, rRNA is present in three distinct sizes (5S, 16S, and 23S), while in eukaryotes, an additional size (5.8S) complements the set (5S, 18S, and 28S). Constituting approximately 60% of the ribosome's mass, rRNA not only provides a structural framework for ribosomal proteins but also plays a catalytic role in peptide bond formation, linking amino acids together to form proteins. The genesis of rRNA occurs within the nucleolus, where ribosomal DNA (rDNA) is transcribed by RNA polymerase I. The resulting precursor rRNA undergoes meticulous processing, including cleavage and modification, before the mature rRNA is assembled with ribosomal proteins and transported to the cytoplasm to participate in protein synthesis.
Three-dimensional molecular model of a ribosome with major and minor subunits, colored spheres indicate atoms and bonds, mRNA strand runs through.

Ribosomal RNA: The Architect of Protein Translation

Ribosomal RNA is the cornerstone of the ribosome's architecture, facilitating the complex process of translating messenger RNA (mRNA) into a polypeptide chain. It ensures the precise alignment of mRNA and transfer RNA (tRNA) within the ribosome, enabling the accurate decoding of genetic instructions. The enzymatic activity of rRNA, particularly its peptidyl transferase function, is pivotal for the formation of peptide bonds that extend the growing polypeptide. Additionally, rRNA is instrumental in the dynamic interactions with various translation factors during the initiation, elongation, and termination stages of protein synthesis, highlighting its versatile role in the translation process.

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1

In ______, ribosomal RNA is found in three sizes: ______, ______, and ______, which are essential for protein synthesis.

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prokaryotes 5S 16S 23S

2

Eukaryotic ribosomal RNA includes an extra size, ______, making the set consist of ______, ______, and ______ sizes.

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5.8S 5S 18S 28S

3

The creation of ribosomal RNA starts in the ______, where it is transcribed from ribosomal DNA by ______ and then undergoes processing.

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nucleolus RNA polymerase I

4

Role of rRNA in peptide bond formation

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rRNA's peptidyl transferase activity catalyzes peptide bond formation between amino acids during translation.

5

rRNA's function in mRNA and tRNA alignment

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rRNA ensures correct positioning of mRNA and tRNA for accurate genetic code reading and amino acid assembly.

6

rRNA interaction with translation factors

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rRNA facilitates the binding and release of translation factors during initiation, elongation, and termination of protein synthesis.

7

The smaller subunit of the ribosome is tasked with ______ and ______ of mRNA.

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binding decoding

8

In protein synthesis, rRNA within the large subunit forms the ______ ______ where amino acids are connected.

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peptidyl transferase center

9

Function of 16S rRNA in protein synthesis initiation

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Binds Shine-Dalgarno sequence on mRNA, aligning ribosome for translation start.

10

Role of 16S rRNA in ribosome positioning

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Facilitates correct ribosome placement on mRNA for efficient protein translation.

11

Use of 16S rRNA in bacterial classification

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Enables identification, classification of bacteria/archaea via conserved evolutionary sequences.

12

Unlike ______, which carries the genetic instructions, ribosomal RNA (rRNA) forms the core of the ribosome and is synthesized in the ______.

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messenger RNA (mRNA) nucleolus

13

Initial step of protein synthesis involving rRNA

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Small ribosomal subunit with rRNA binds to mRNA's start codon.

14

rRNA's role in peptide bond formation

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rRNA's peptidyl transferase activity catalyzes peptide bonds, aiding protein chain elongation.

15

Importance of rRNA in elongation phase

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Structural and catalytic functions of rRNA are crucial for protein synthesis elongation.

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