Protein Synthesis

Protein Synthesis

1. Transcription

   • A strand of mRNA is produced using one strand of complementary DNA.
     • mRNA- Messenger Ribonucleic Acid
   • 1. An RNA Polymerase enzyme attaches to a section of DNA.
     • 2. This enzyme breaks up the Hydrogen bonds between the bases, in the DNA.
       • 3. The DNA separates, leaving its strands exposed.
         • 4. The RNA Polymerase makes an mRNA using free floating nucleotides
           • 5. One of the DNA strands is used as a template to make this mRNA.
             • 6. Complementary base-pairing ensures that the mRNA is an exact match.
               • 7. Lots of condensation reactions occur to join all the nucleotides.
                 • The mRNA that is produced is pre-mRNA,  it contains both introns (non-coding bases) and exons.
                 • Splicing occurs to remove the introns.
                 • 8.Finally, the mRNA detaches and leaves the nucleus.
   • This is the first process of protein synthesis.

2. Translation

   • A polypeptide (protein) is produced using the mRNA as a template.
   • 1. Firstly, the mRNA leaves the nucleus through the nuclear pore.
     • 2. It then attaches to a ribosome in the cytoplasm.
       • 3. The first set of codon (triplet bases) is translated, on the mRNA.
         • A codon is a set of three bases.
         • 4. A tRNA with the correct complementary anticodon, comes and pairs up with the first codon.
           • tRNA-Transfer Ribonucleic Acid
           • 5. The tRNA has an amino acid attached to it at the other end of it.
             • 6. Next, the second codon on the mRNA is translated using another tRNA.
               • 7. Now, there are two amino acids next to each other, and they form a peptide bond by a condensation reaction.
                 • This process is repeated until a stop signal is reached, when the protein detaches and leaves the cell to do its job.
   • This is the final process of protein synthesis.

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