Protein Synthesis

Protein Synthesis

1. Proteins info

   • Made of amino acids. A chain of which is called a polypeptide. Peptide bonds hold them together
   • Two types: fibrous and globular. Fibrous form bundles and globular are folded into globe-shaped molecules
   • Made up of several thousand amino acids

2. RNA

   • messenger, transfer and ribosomal
   • Single stranded
   • Sugar is ribose
   • The base Uracil replaces Thymine

3. Transcription

   • 1) The enzyme RNA polymerase binds to the strand and the DNA unwinds here. The enzyme Helicase does this.
     • 2) Only one strand is used and the triplets are read by an enzyme and are corresponded into codons.
       • 3)When RNA polymerase reaches the terminator sequence, transcription is completed.
         • 4) The two DNA strands rejoin
   • Occurs in nucleus

4. RNA Splicing: Introns are NOT needed for the protein formation so these are cut out of the strand. The exons are then joined together to from the final transcript of mRNA.

5. Translation

   • 1) The edited mRNA leaves the nucleus and travels to a ribosome.
     • 2) The ribosome moves along the mRNA strand and reads the codons.
       • 3) Each codon corresponds to a triplet in DNA, thus coding for a particular amino acid.
         • 4) The corresponding tRNA molecule brings along the anti-codon and picks up the correct amino acid along the way.
           • 5) This continues until a STOP codon is reached and translation terminates. The amino acids have now formed a chain and it breaks off and travels to the place it's needed.
   • Occurs in cytoplasm and ribosomes