TRANSCRIPTION AND TRANSLATION
The Central Dogma of Molecular Biology states that there is a flow of information from the genetic instructions written in ______, via the messenger ______, to the ______ products that perform most of the work in a cell.
The first part of this process is called transcription. Just as you might transcribe your notes after a lecture to make them neater and more organized, but not fundamentally changed from one form to another, transcription involves a transfer of information between two very similar molecules, DNA and RNA.
What are 3 differences between these 2 molecules?
1.
2.
3.
The process of transcription takes place in the ______ of a eukaryotic cell.
The sequence of DNA that codes for a particular protein is known as a ______.
The enzyme that is responsible for adding the appropriate bases to build the messenger RNA is ______.
This enzyme needs to know where to start the process of transcription. In front of each gene is a region where the enzyme binds and begins mRNA synthesis. This region is called the ______. At the end of each gene is a termination site, where the enzyme's job is done and the mRNA is released.
But we are not quite done with transcription yet. There are parts of the gene sequence that do NOT code for protein; these ______ must be removed before translation. The coding regions (called ______) must be attached together, and a cap and tail added.
Now the messenger is ready to leave the nucleus and travel to the cytoplasm of the cell, where it will be recognized by the protein assembly machines known as ______.
This second part of the process is called translation. Just as you might be able to translate a letter or a conversation from Spanish to English, or Armenian to Chinese, this process of translation represents a dramatic change from the language of nucleic acids (composed of nucleotide building blocks) to the very different language of proteins (composed of ______ building blocks).
Remember that protein structure is complex and may be divided into primary, secondary, tertiary, and often quaternary levels. The primary structure is the sequence of amino acids that are put together to make a polypeptide, and that is what happens during translation.
The genetic code is written in triplets (units of three mRNA bases). These triplets are called ______.
Each triplet is complementary to a single anticodon found on ______ RNA molecules. At the opposite end of each tRNA, a specific amino acid is attached. This is the key to translation.
If you know the DNA sequence of a gene, you can figure out the complementary mRNA sequence, and then, using the codebook, the sequence of amino acids in the protein. Some amino acids will be attracted to each other (e.g., by hydrogen bonds), thereby creating the coils and folds of secondary protein structure, and ultimately, the tertiary 3-dimensional shape of the protein, which determines function.