2. (a) Consider Amino Acid Sequence 2. How is Amino Acid Sequence 2 different from Amino Acid Sequence 1? Amino Acid Sequence 2: H,N*-Methionine-Valine-Histidine-Leucine- Threonine-Proline-Valine-Glutamic Acid-CO0- (b) Write a potential mRNA sequence for Amino Acid sequence 2, using the same codons for any given amino acid if it is present in both sequences.

Exploring the Structure of the 30S Ribosomal Subunit Go to www.pdh.org and bring up PDB file 1GIX, which shows the 30S ribosomal subunit, the three tRNAs, and mRNA. In the box on the right titled ‘Biological Assembly.� click “More Images.� and then scroll down to look at the Interactive Vic By moving your cursor over the image, you can rotate it to view it from any perspective. a. How are the ribosomal proteins represented in the image? b. How is the 16S rRNA portrayed? c. Rotate the image to see how the tRNAs stick out from the structure. Which end of the tRNA is sticking out? d. Where will these ends of the tRNAs lie when the 50S subunit binds to this complex?

Codon-Anticodon Recognition: Base-Pairing Possibilities (Integrates with Chapter 11.) Draw base-pair structures for (a) a G:C base pair. (b) a C:G base pair. (C) a G:U base pair, and (d) a U:G base pair. Note how these various base pairs differ in the potential hydrogen-bonding patterns they present within the major groove and minor groove of a double-helical nucleic acid.

VISUALIZE Sketch a pyrimidine nucleotide subunit that would be found only in RNA. Circle and label the three components that make up this type of nucleotide. Explain what changes in the functional groups of this subunit would have to occur for it to be found in a DNA molecule.