Today we talked about protein synthesis in class. Since DNA is double-stranded and has a large size, it cannot leave the nucleus to synthesize protein. So in order to convert the order of DNA bases to protein, the first step would be the process of translating DNA language to mRNA language, that is also known as "transcription". To start this process, the DNA would first have to break apart to allow access for RNA polymerase to begin translation. After this step is done, the introns in the mRNA are cut out and only exons are left in mRNA because introns are useless codes, also known as "junk DNA". Also, a cap made of Guanine (G-cap) and a tail made of multiple Adenine bases (poly-A tail) are added to the mRNA strand as well, to protect it from being eaten away by enzymes in cytoplasm.
After the mRNA leaves the nucleus and enters the cytoplasm, the process of converting mRNA language to amino acids starts. This process, also known as "translation" begins with mRNA bonding with ribosome. The ribosome will read each codon (3-letter message) on mRNA, and match it with an anti-codon, carrying an amino acid. The message always begins with AUG (Met) and ends with UAG, UGA or UAA. After each codon is processed, the amino acid will connect to other amino acids and create a long string. When the translation is finished, the long string of amino acids will leave the ribosome, and will become protein.
- Andy Liu '15
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