Translation and Posttranslational Processing of Proteins I

Transcription can be simply understood as a process of information transfer: since DNA and RNA are chemically and structurally similar (both are nucleic acids), the DNA can act as a direct template for the synthesis of RNA by complementary base-pairing. As the term ______ signifies, it is as if a message written out by hand is being converted, say, into a typewritten text. The language itself and the form of the message do not change, and the symbols used are closely related (nucleic acids). In some genes their expression involves one-step process, ______; in those genes their final product is an RNA molecule itself, such as the tRNAs and rRNA. However, most genes in a cell their expression involve twostep processes, ______ followed by translation. In those genes once an mRNA has been produced by ______ and processed, the information present in its nucleotide sequence is used to synthesize a protein. This second stage of gene expression is called translation; it involves using the information contained in mRNA molecule to direct the synthesis of polypeptide by ribosomes.