Extracted text: Exercise B: Peptide Bond Formation Figure 2 shows two individual amino acids, and then those same two amino acids after they have been linked together by a peptide bond to form a dipeptide. Addition of more amino acids linked by peptide bonds would form a polypeptide, the precursor to a functional protein. H H H. H H +| | H-N-Ċ- ċ-0 H-N-Ć- Ĉ-O H-N-Č -C. N-C-C- H CH2 H. CH2 H. CH2 H CH2 SH SH NH2 NH2 Figure 2. Formation of a peptide bond between two amino acids. Answer the below questions in your own document. F1. Which two amino acids are shown on the left side of Figure 2? Use the Figure They 3.2 from your text to answer this. 2. To which chemical groups do these amino acids belong? 3. Were you able to identify their chemical characteristics based on your rules? If not, you should go back and revise your rules! On the dipeptide shown in Figure 2, label the peptide bond that was formed when the two individual amino acids were joined. Label the free amino and carboxyl groups at the ends of this dipeptide (not in the R groups). These are often referred to as the N- terminus (amino-terminus) and the C-terminus (carboxyl-terminus) of a peptide or polypeptide. (Note: “peptide" refers to a chain of a small number of amino acids, whereas "polypeptide" refers to a longer chain, potentially that corresponding to an entire protein.) Chentical Groug Rulas Bae
Extracted text: Answer the below questions in your own document. 1. On the amino acid shown in Figure 1, label the a-carbon. 2. The a-carbon of each of the 20 amino acids is bonded to one hydrogen atom, one amino group, one carboxyl group, and one R group (more on that below). You should recognize the amino and carboxyl groups from our discussion of functional groups in organic molecules. Circle and label* the amino group and the carboxyl group in Figure 1. *Note: our goal in this question, and in similar questions throughout this lab, is for you to be able to identify specific structures. You can do this circling/labeling in whatever way is easiest for you. You might want to draw the structures on a piece of paper, or use a computer program (like Powerpoint, Photoshop, Paint, Preview, etc.) to draw on these images. Whatever is easiest for you! 3. The last bond an a-carbon in an amino acid makes is to an R group,or side- chain. Circle and label the R group in Figure 1. Figure 3.2 on page 81 of They are categorized into 4 chemical groups: nonpolar, uncharged polar, acidic, and basic. our textbook shows the structures of all 20 amino acids. 4. Using the three groups you identified in Figure 1 as a reference, what is the only thing that is different about each of the 20 amino acids? 5. Look at the amino acids in each of the four groups and compare them to the ones in the other groups. Figure out rules that describe what the members of each group have in common so that you will be able to identify the chemical group for each of the 20 amino acids if you are shown its structure. Record your rules in a table similar to the one shown below. Chemical Group Rules Describing Membership in this Group