| Protein synthesis, transcription and translation |
protein synthesis, transcription and translation
| THE PLAYERS: DNA, RNA nucleotides, mRNA and RNA polymerase |
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- The DNA of a gene is not used to make polypeptides in the nucleus. Instead, RNA copies of the gene’s code are made.
- One strand of the gene’s DNA is used to make many copies of messenger RNA, which have a matching code. This process is transcription.
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- The base sequence of mRNA is complementary to the coding strand of DNA. Except of course U instead of T
- RNA polymerase joins the RNA nucleotide to each other
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| INTERLUDE: The mRNA passes out of the nucleus and attaches to ribosomes on the rough endoplasmic reticulum. |
| STEP TWO TRANSLATION:
THE PLAYERS: mRNA, ribosomes, tRNA and amino acids
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- The rough endoplasmic reticulum has a supply of transfer RNA molecules that have specific amino acids attached. The tRNA molecules have anticodons that bind to the corresponding mRNA codon.
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- As the mRNA moves through a ribosome, the amino acids carried by the tRNA are combined in the correct sequence to form the polypeptide. This process is translation.
- The polypeptides formed can then be used to make a specific protein, which may be, for example, an enzyme, a membrane protein or a structural protein.
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