Lecture Notes: D1.2 HL Protein Synthesis [IB Biology HL]

Introduction to Protein Synthesis

• Protein Synthesis is a fundamental biological process.
• Essential for the functioning of cells and the production of proteins.

Main Stages of Protein Synthesis

1. Transcription

   • Occurs in the nucleus.
   • DNA is transcribed to form messenger RNA (mRNA).
   • mRNA carries the genetic information from DNA to the ribosome.

2. Translation

   • Takes place in the ribosome.
   • mRNA is decoded to produce a specific polypeptide or protein.
   • Involves ribosomal RNA (rRNA) and transfer RNA (tRNA).

Key Components

• DNA: Contains the genetic blueprint.
• mRNA: Messenger RNA that conveys genetic information.
• tRNA: Transfer RNA brings amino acids to the ribosome.
• rRNA: Ribosomal RNA, part of the ribosome structure.

Detailed Steps in Protein Synthesis

• Initiation:

  • mRNA binds to the small ribosomal subunit.
  • tRNA carrying methionine binds to the start codon.

• Elongation:

  • tRNA brings amino acids to the ribosome.
  • Amino acids are linked together forming a polypeptide chain.

• Termination:

  • Occurs when a stop codon is reached.
  • The polypeptide is released.

Important Concepts

• Codons: Triplets of nucleotides in mRNA that dictate amino acid sequence.
• Anticodons: Triplets of nucleotides in tRNA complementary to mRNA codons.

Significance of Protein Synthesis

• Vital for cell function and biological processes.
• Errors in protein synthesis can lead to diseases or dysfunctional proteins.

Review Questions

• What roles do each type of RNA play in protein synthesis?
• Describe the process of translation and its stages.
• How do codons and anticodons interact during protein synthesis?

Conclusion

• Protein synthesis is a complex but essential process for life.
• Understanding each step helps in comprehending how cells operate and produce necessary proteins.