Protein Synthesis

• Basic principles of protein synthesis are the same in eukaryotes and prokaryotes.
• Each cell inherits the neccessary info for synthesizing specific proteins.
  • Transcription into mRNA
    • Promoters: Start signals for RNA synthesis
    • Terminators: Stop signals for RNA synthesis
    • From 5 pair to 3 pair
  • rRNA constitutes ribosomes. Ribosomes are ²/₃ rRNA and ¹/₃ Protein.
    • 2 binding sites (P/A)
    • starts scanning at 5' even while mRNA is being constructed.
  • tRNA
    • Anticodon attaches to mRNA
    • 3' end attaches to amino acid
  • Translation - Synthesis of Proteins
    • (1) Initialization:
      • Smaller ribosomal subunit attaches to mRNA at 5' end at initialization (start) codon.
      • First tRNA comes into place to bond with mRNA Codon.
      • Larger Ribosomal subunit attaches to the smaller subunit and initator tRNA becomes locked into P site.
    • (2) Elongation:
      • 2^nd codon is put under A site.
      • tRNA with anticodon corresonding to DNA codon locks into place.
      • Peptidy transferase forges a peptide bond between 2 amino acids.
      • First tRNA is released
      • Ribosome moves down, 2^nd tRNA/Amino acid locks into P spot, 3^rd tRNA moves into A position.
      • Continues like this...
    • (3) Termination:
      • When termination codon is reached, polypeptide chain is released and the two ribosomal subunits seperate.

Redefining Mutations:

• A mutation is a change in the sequence or number of nucleotides in the nucleic acid of a cell.
• Point mutations - involve a single nucleotide
• Frame shifts - deletion - insertion moves triplet positions.