M03.04.01 Translation in Gene Expression

Translation is the second stage in gene expression, where the nucleotide sequence of a messenger RNA (mRNA) molecule is converted into the amino acid sequence of a protein. This process involves various molecules and complexes that ensure the accurate synthesis of proteins based on genetic instructions.

The Genetic Code

The genetic code defines the relationship between the nucleotide sequences in DNA (or its RNA transcripts) and the corresponding amino acid sequences in proteins. Each amino acid is specified by one or more nucleotide triplets, known as codons.

Key Points of the Genetic Code

Role of mRNA and tRNA

1. Messenger RNA (mRNA):
   • Serves as the working copy of the gene.
   • Contains codons that specify the amino acids in the protein.
2. Transfer RNA (tRNA):
   • Acts as an adapter molecule.
   • Couples codons in mRNA with their corresponding amino acids, ensuring they align in the correct sequence.

Ribosomes: The Molecular Machines

• Ribosomes are complexes of proteins and ribosomal RNA (rRNA) that function as the sites of protein synthesis.
• They coordinate the interactions between mRNA, tRNA, enzymes, and various protein factors necessary for translation.

Post-Translational Modifications

After translation, many proteins undergo post-translational modifications, which are essential for preparing them to perform their specific roles in the cell. These modifications can include phosphorylation, glycosylation, and ubiquitination.

Points to Remember

• Translation is the process of synthesizing proteins from mRNA.
• The genetic code consists of codons that determine the amino acid sequence.
• Ribosomes facilitate the translation process by bringing together mRNA and tRNA.
• Post-translational modifications are crucial for protein functionality.

Bibliography

1. Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K., & Walter, P. (2015). Molecular Biology of the Cell (6th ed.). Garland Science.
2. Lodish, H., Berk, A., Zipursky, S. L., Matsudaira, P., Baltimore, D., & Darnell, J. (2000). Molecular Cell Biology (4th ed.). W.H. Freeman.
3. Berg, J. M., Tymoczko, J. L., & Stryer, L. (2012). Biochemistry (7th ed.). W.H. Freeman.