III. Translation

A. Components B. Translation Initiation C. Translation Elongation

Translation

mRNA -> polypeptide

Occurs in ribosomes- cytoplasm or surface of RER

components

• tRNA

• Anticodon

• Aminoacyl tRNA

• Ribosomes

tRNA

• Transcribed from DNA

• 3D structure

• Base-pairing (H bonds) within molecule

• Unpaired nucleotides -> loops

•  anticodon

  • Complementary and antiparallel to mRNA codon

Anticodon

• 3 specific bases on loop of tRNA

• Complementary to codon in mRNA

• mRNA: 3; A-U-G 5’ Codon

• tRNA: 5’ U- A-C 3’ anticodon

• 1 Amino acid for each anti codon

Aminoacyl tRNA

A tRNA molecule linked to an AA,

High Energy (charged molecule, ATP involved in binding)

Enzymes load amino acid onto amino acid to tRNA

Delivers amino acid to ribosome

Loaded amino acid has anticodon

Ribosomes

Structure that carries out translation

Comprised of protein and rRNA

Small unit and large unit

Has A site, where tRNA binds

P site where peptide binds and grows, E site where exits to lumen of RER

Ribosomal RNA: rRNA

• Catalyzes peptide bond formation, Ribozyme

• Created by RNA polymerase

Translation Initiation

Small ribosomal subunit binds to mRNA and first tRNA (complementary to start codon)

Large ribosomal subunit completes the initiation process

Translation Elongation

• Series of repeated cycles

  • Each adds single AA to growing polypeptide chain

  • Ribozyme rRNA enzyme

    • Catalyzes peptide bond formation

    • A and p

  • Translocation

    • Happens at exit site

    • Large and small separate

  • Look at photos