Question
Which type of RNA molecule contains anticodons, and what role does it play in protein synthesis?
Solution
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The type of RNA molecule that contains anticodons is transfer RNA (tRNA). During protein synthesis, tRNA plays a crucial role in translating the genetic code from messenger RNA (mRNA) into a sequence of amino acids to form a protein. This process occurs within the cell's ribosome and involves several key steps:
The type of RNA molecule that contains anticodons is transfer RNA (tRNA). During protein synthesis, tRNA plays a crucial role in translating the genetic code from messenger RNA (mRNA) into a sequence of amino acids to form a protein. This process occurs within the cell's ribosome and involves several key steps:
1. Transcription: The first step in protein synthesis is transcription, where a segment of DNA is transcribed into mRNA in the nucleus. The mRNA molecule carries the genetic information that encodes for a specific protein.
2. mRNA Processing: Before the mRNA can be translated, it undergoes processing. This includes splicing, where introns (non-coding regions) are removed, and exons (coding regions) are joined together. A 5' cap and a poly-A tail are also added to the mRNA for stability and to facilitate its export from the nucleus.
3. Translation Initiation: The processed mRNA is transported out of the nucleus into the cytoplasm, where it binds to a ribosome. The ribosome reads the mRNA in sets of three nucleotides called codons.
4. tRNA Charging: Each tRNA molecule is "charged" with a specific amino acid by an enzyme called aminoacyl-tRNA synthetase. There are different tRNAs for each of the 20 amino acids used to make proteins.
5. Translation Elongation: During elongation, tRNA molecules recognize and bind to the appropriate codon on the mRNA strand through their anticodon. The anticodon is a set of three nucleotides on the tRNA that are complementary to the mRNA codon. For example, if the mRNA codon is AUG, the tRNA anticodon would be UAC.
6. Peptide Bond Formation: Once the tRNA is bound to the mRNA, the amino acid it carries is added to the growing polypeptide chain. A peptide bond is formed between the amino acid and the last amino acid of the chain.
7. Translocation: The ribosome moves along the mRNA, reading the next codon and allowing another tRNA to bind. The first tRNA is then released to be recharged with another amino acid.
8. Translation Termination: When the ribosome encounters a stop codon on the mRNA (UAA, UAG, or UGA), the translation process ends. The completed polypeptide chain is released, and the ribosome disassembles.
9. Protein Folding and Post-translational Modification: The polypeptide chain folds into its functional three-dimensional structure. Some proteins may also undergo post-translational modifications, such as the addition of carbohydrate groups or cleavage into smaller units, to become fully functional.
In summary, tRNA molecules with their anticodons are essential for the translation phase of protein synthesis, where they deliver the correct amino acids to the ribosome in the sequence dictated by the codons of the mRNA. This process ultimately results in the formation of a new protein molecule.
1. Transcription: The first step in protein synthesis is transcription, where a segment of DNA is transcribed into mRNA in the nucleus. The mRNA molecule carries the genetic information that encodes for a specific protein.
2. mRNA Processing: Before the mRNA can be translated, it undergoes processing. This includes splicing, where introns (non-coding regions) are removed, and exons (coding regions) are joined together. A 5' cap and a poly-A tail are also added to the mRNA for stability and to facilitate its export from the nucleus.
3. Translation Initiation: The processed mRNA is transported out of the nucleus into the cytoplasm, where it binds to a ribosome. The ribosome reads the mRNA in sets of three nucleotides called codons.
4. tRNA Charging: Each tRNA molecule is "charged" with a specific amino acid by an enzyme called aminoacyl-tRNA synthetase. There are different tRNAs for each of the 20 amino acids used to make proteins.
5. Translation Elongation: During elongation, tRNA molecules recognize and bind to the appropriate codon on the mRNA strand through their anticodon. The anticodon is a set of three nucleotides on the tRNA that are complementary to the mRNA codon. For example, if the mRNA codon is AUG, the tRNA anticodon would be UAC.
6. Peptide Bond Formation: Once the tRNA is bound to the mRNA, the amino acid it carries is added to the growing polypeptide chain. A peptide bond is formed between the amino acid and the last amino acid of the chain.
7. Translocation: The ribosome moves along the mRNA, reading the next codon and allowing another tRNA to bind. The first tRNA is then released to be recharged with another amino acid.
8. Translation Termination: When the ribosome encounters a stop codon on the mRNA (UAA, UAG, or UGA), the translation process ends. The completed polypeptide chain is released, and the ribosome disassembles.
9. Protein Folding and Post-translational Modification: The polypeptide chain folds into its functional three-dimensional structure. Some proteins may also undergo post-translational modifications, such as the addition of carbohydrate groups or cleavage into smaller units, to become fully functional.
In summary, tRNA molecules with their anticodons are essential for the translation phase of protein synthesis, where they deliver the correct amino acids to the ribosome in the sequence dictated by the codons of the mRNA. This process ultimately results in the formation of a new protein molecule.
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