Skip to main content

Termination codons

TERMINATION CODONS

Termination codons, also known as stop codons, are specific sequences of three nucleotides in mRNA that signal the termination of protein synthesis during translation. There are three stop codons in the standard genetic code, and they do not code for any amino acids. Instead, they serve as signals for the ribosome to release the newly synthesized polypeptide chain. The three stop codons are:

  1. UAA (UAG in DNA):
    • UAA is one of the three termination codons, and it is known as the "ochre" stop codon.
  2. UAG (UAA in DNA):
    • UAG is another termination codon, and it is often referred to as the "amber" stop codon.
  3. UGA (TGA in DNA):
    • UGA is the third termination codon, and it is also known as the "opal" stop codon.

Key Features of Termination Codons:

  1. Role in Protein Synthesis:
    • Termination codons signal the end of the translation process, instructing the ribosome to release the nascent polypeptide chain.
  2. No Corresponding Amino Acid:
    • Unlike other codons that code for specific amino acids, stop codons do not specify any amino acid. Instead, they act as signals to terminate translation.
  3. Interaction with Release Factors:
    • The recognition of stop codons by release factors triggers the hydrolysis of the bond between the final tRNA and the last amino acid in the polypeptide chain.
    • Release factors facilitate the release of the completed polypeptide from the ribosome.
  4. Presence of Multiple Stop Codons:
    • There are three different stop codons in the genetic code, providing redundancy. This redundancy contributes to the flexibility and robustness of the translation process.
  5. Codon Usage and Variation:
    • The frequency of occurrence of stop codons can vary among different organisms, and there may be variations in the frequency of stop codon usage for the same organism in different genes.
    • The variation in stop codon usage has implications for gene expression and may be influenced by factors such as tRNA availability and translation efficiency.

Examples of Termination Codons in an mRNA Sequence:

  • ... AUG (start codon) ... amino acid sequence ... UAA (stop codon) ...
  • ... AUG (start codon) ... amino acid sequence ... UAG (stop codon) ...
  • ... AUG (start codon) ... amino acid sequence ... UGA (stop codon) ...

In summary, termination codons play a crucial role in the accurate and controlled termination of protein synthesis during translation. Their recognition by release factors ensures the proper release of the synthesized polypeptide chain from the ribosome, completing the translation process.

Popular posts from this blog

Welcome to Let Me Explain (A Part of bionexts.in)

  Welcome to my Blogspot! Here, I explain various topics related to Bio-Medical Science with detailed class study notes. I trust it will be helpful for you. MISSION OF THE PROJECT My mission is to provide you Class Study Notes with a clear understanding of various Bio-Medical related topics, especially professional courses, using easy language. Don't worry; I'll also include other topics.  ☺️ CLICK ANY ONE OF THE SUBJECTS Immunology   Techno Professional Skill  Developmental Biology   Molecular Biology Cell Biology Genetical Engineering Biostatistics Bioinformatics Basic Acclimatization Skill Animal Biotechnology Medical Biotechnology Industrial Biotechnology Plant and Agricultural Biotechnology Research Methodology, IPR and Bioethics Are You Preparing For The GATE Examination Also! Click Here  Click Here   Are You Preparing For The UPSC Examination Also! Click Here Yes And Normal General Science Click Here And I'm going to explain to you the biology t...
Read more

Animal Biotechnology

On this page, you will find all topics related to Immunology! Here Every Major Topic Includes Sub-Major Topics. Find the topic you want to learn! Describe the basics of animal cell culture Introduction Definition, scope, and importance. Historical developments in animal biotechnology Basic requirement for animal cell culture Types of animal cells and their characteristics. Types of Culture Primary and secondary culture. Cell Cine & Maintenance and preservation of cell lines. history of animal cell culture Suspension culture ,  Cell cloning and hybridization ,  3D cultures ,  Scaling up & Growth factors.  Cell line and maintenance, viability test, cytotoxicity  Describe the cell culture and vaccine production Application of cell culture technology in the production of different vaccines and pharmaceutical proteins. Explain reproductive structures and artificial fertilization  Structure of sperm and ovum Cryopreservation of sperms and ova of...
Read more

MOLECULAR BIOLOGY

On this page, you will find all topics related to Immunology! Here Every Major Topic Includes Sub-Major Topics. Find the topic you want to learn! Genome Introduction to the Genome Prokaryotic and Eukaryotic Genome The Central Dogma of life C value paradox Genes are made of DNA Semi-conservative mode of DNA replication Cot Curve   Repetitive DNA sequences (satellite DNA, LINE, SINE etc) DNA melting and buoyant density Neucleosome Phasing DNA Replication and Recombination Replication initiation, elongation and termination in prokaryotes and eukaryotes DNA Replication (Explain) The Meselson-Stahl experiment Homologous Recombination at the molecular level The Holliday Model Double-stranded DNA repair model Removing of the DNA Primer / Flap Model DNA damage and Repair Mutation- Nonsense, missense and point mutations Intragenic and Intergenic suppression Frameshift Mutation Mutagens Transposition Transposable genetic elements in prokaryotes and eukaryotes Mechanism of transposition Role ...
Read more