Protein+Synthesis


 * Protein Synthesis **


 * Transcription: **
 * ** Where? Occurs inside the nucleus. **
 * ** Why? **** It occurs to produce the RNA molecule **
 * ** What? **** One strand of the DNA double helix is used as a template by the RNA polymerase to synthesize a messenger RNA (mRNA). The mRNA then migrates from the RNA polymerase to synthesize a messenger RNA. Then, that mRNA moves from the nucleus into the cytoplasm. The coding mRNA sequence can be described as a unit of three nucleotides called a codon. **
 * ** To start, you need: **
 * ** DNA **
 * ** Free RNA nucleotides **
 * ** RNA Polymerase **


 * Four Steps of Transcription: **
 * 1) ** RNA polymerase attaches to a promoter region of DNA **
 * 2) ** RNA polymerase opens the DNA helix, makes a bubble and one strand will act as a template **
 * 3) ** RNA polymerase moves down the DNA molecule attaching complementary RNA nucleotides as it goes **
 * ** Remember: The DNA Adenine pairs with Uracil not Thymine **
 * 1) ** Transcription stops when RNA polymerase reaches the terminator region of DNA **




 * Translation: **

** What? **** Translation is the process where ribosomes synthesize proteins, using the mature mRNA transcript produced during transcription. **

 * =====** After transcription, the mRNA leaves the nucleus and travels out to the cytoplasm **=====
 * ** through a nuclear pore **




 * Six Steps of Translation: **
 * 1) **Ribosome binds to the mRNA, at the start codon (AUG) and the tRNA molecule with the anti-codon UAC also binds**
 * 2) **Another tRNA molecule attaches to the ribosome next to the first tRNA. This tRNA will pair with the codon of mRNA following the AUG codon**
 * 3) **Ribosome will form a peptide bond between the two adjacent amino acids**
 * 4) **Ribosome will move down the mRNA. When it moves, the tRNAs will each move down a site**
 * **The site is now empty, allowing a new tRNA to attach**
 * 1) **Continues until it hits a stop codon**
 * 2) **rRNA breaks apart into 2 subunits and the mRNA is broken apart so the nucleotides can be recycled. The tRNA returns to the cytoplasm to reconnect to amino acids for the future.**


 * Overview: **
 * ** Ribosome attach to mRNA, and then move along the mRNA adding amino acids to the growing polypeptide chain. **

** Translation: Details **

 * 1) ** A mature mRNA transcript, a ribosome, several tRNA molecules and amino acids are involved in translation. **
 * ** There is a specific tRNA for each of the 20 different amino acids. **
 * 1) ** A ribosome then attaches to the mRNA transcript. **
 * 2) ** A tRNA molecule transports an amino acid to the ribosome. The anticodon on the tRNA molecule matches the one in the mRNA. The tRNA with the anticodon "UAC" bonds with methionine. It always transports methionine. Transfer RNA molecules with different anticodons transport other amino acids. **
 * 3) ** A second tRNA molecule then bonds to the mRNA at the ribosome. Again, the codes must match. **
 * 4) ** A bond is formed between the two amino acids. **
 * 5) ** The tRNA bonded to methionine drops off and can be reused later. **
 * 6) ** The ribosome moves along the mRNA to expose another codon for a tRNA molecule. **
 * 7) ** The only tRNA molecule that can bond to the GAU site is a molecule with a CUA anticodon. Transfer RNA molecules with CUA anticodons are specific for asparagine. **
 * 8) ** Asparagine is now added to the growing amino acid chain. **




 * The link below will take you to an animation that summarizes transcription and translation. **
 * ** [|Translation] **


 * The links below can help you further understand transcription and translation. **
 * [|Transcription/translation Overview]
 * [|Transcription and Translation]
 * [|Transcription/Translation]