Translation

Introduction

• Translation is a crucial step in protein synthesis, where the genetic information carried by mRNA is used to build a protein.

1. Initiation of Translation

• Translation begins when the mRNA molecule travels from the nucleus to the cytoplasm and attaches to a ribosome.
• The ribosome serves as the cellular machinery for protein synthesis.

2. tRNA and Amino Acids

• Transfer RNA (tRNA) molecules play a key role in translation.
• tRNA molecules transport specific amino acids to the ribosome.
• Each tRNA carries an amino acid that corresponds to a particular codon on the mRNA.

3. mRNA Codons and Amino Acids

• Each mRNA molecule contains codons, which are sequences of three nucleotides.
• Each codon codes for a specific amino acid.
• The genetic code is universal, meaning that the same codon codes for the same amino acid in all organisms.

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Translation

4. Start and Stop Codons

• The first codon on the mRNA is called the start codon (AUG).
• The start codon signals the beginning of translation.
• The last codon on the mRNA is a stop codon (e.g., UAA, UAG, UGA).
• Stop codons signal the end of translation, and the protein is released.

5. Complementary Base Pairing

• During translation, the anti-codons on tRNA molecules match up with the codons on the mRNA through complementary base pairing.
• This ensures that the correct amino acids are added in the right order.

6. Peptide Bond Formation

• As tRNA molecules bring amino acids to the ribosome, peptide bonds form between adjacent amino acids.
• This process continues, and a polypeptide chain (protein) is formed.

7. Recycling tRNA

• After delivering their amino acids, tRNA molecules exit the ribosome and collect another specific amino acid.
• They can be reused in subsequent rounds of translation.

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Translation

8. Post-Translation Modifications

• After translation, the newly synthesised polypeptide chain may undergo modifications.
• These modifications can include cutting and combining polypeptide chains or adding phosphate or carbohydrate groups to the protein.
• These modifications are essential for the protein's functionality.

Summary

Translation is the process by which the genetic information in mRNA is used to build a protein. It begins with initiation, where the mRNA attaches to a ribosome. tRNA molecules transport specific amino acids to the ribosome, and codons on the mRNA code for specific amino acids. Complementary base pairing between anti-codons and codons ensures accuracy. Peptide bonds form between amino acids to create a polypeptide chain, which may undergo post-translation modifications for its final functionality. Stop codons signal the end of translation. Translation is a fundamental process in protein synthesis, essential for the functioning of all living organisms.