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In this exercise, the structures of different amino acids will be drawn and analyzed using MarvinSketch and MarvinView. Instructions The following instructions are for MarvinSketch 23.1. Instructions for this Exercise: Part 1. Isoleucine stereochemistry 1. Open MarvinSketch. For this exercise, the drawing functions of MarvinSketch will be used. 2. For help on any function in MarvinSketch, go to the "Help" menu and click on "Help Contents." Use the search function to answer your queries. 3. In the new window, use the Template Library Manager (under Edit) to obtain the structure of L-isoleucine. Click the structure and close the window. 4. Add isoleucine to the main window and unselect all items by pressing "esc" on the keyboard. Part 2. Peptide structure and ionization 1. In the same window, draw the following peptide: D-I-R-T by adding the other amino acids to the isoleucine and generating the peptide bonds. 2. For simplicity, keep the amino groups in the "- NH2 " form and keep the carboxylic acid groups protonated. 3. Select the entire structure and clean and/or check the structure using the "Clean 2D" and "Check Structure" commands. 4. Select the entire structure and calculate the pKa values. Use this combined information to answer the questions below. Questions 1. Post a picture of your structure here. 2. What is the pKa for the N-terminal amino group of the peptide, D-I-R-T? 3. Which group has a pK2 of 11.66 ? Which group has a pKa of 4.00 ? 4. In this peptide, which group has the lowest pKa ? 5. How many chiral centers are found in the peptide, D-I-R-T? 6. At pH7.4, what is the overall charge of the major species of the peptide? 7. At pH 9.0, what is the major form of each ionizable group