Ch. 17 Overview

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------------------Online---------------------------------------bwilcox@edison.edu Ch. 17 From Gene to Protein

Overview

You may recall the following sequence from the introductory lecture: DNA - mRNA - ribosome - protein. Fig. 17.2 (b) from your text illustrates this process in a eukaryotic cell.

One strand of the double DNA double helix is called the "template strand." RNA polymerase attaches to it and catalyzes the production messenger RNA or m-RNA. This process is similar to how DNA polymerase copies DNA. The RNA processing step is described in Fig. 17.9 on page 303 of your text.

Messenger RNA is similar to DNA but differs from DNA in the following ways:

m-RNA is single stranded
substitutes uracile for thymine
the sugar is ribose instead of deoxyribose

Fig. 17.6 shows RNA polymerase involved in the dehydration synthesis of mRNA, using the DNA strand as a template. This process is called "transcription." A transcript is a copy.

Fig. 17.6 Transcription