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carbon - Bio 20A Supplementary Problems for Carbon and...

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Unformatted text preview: Bio 20A Supplementary Problems for Carbon and Molecular Diversity 4/1/08 1. Identify the functional groups present in the urea molecule (see text Fig. 51.3; p. 1096). 2. Identify the asymmetric carbon atom (or atoms) in the molecule below, if any. 3. I made up the imaginary molecule below to display all the functional groups in Fig. 3.1. Draw a line from the name of the functional group on the right to its occurrence in the structure. Notice that the functional groups are shown in the ionic form that would predominate at pH7. I also made an intentional mistake in the structure. Indicate the location of the mistake. 1 of 3 Bio 20A Supplementary Problems for Carbon and Molecular Diversity 4/1/08 4. The normal form of a certain protein has the amino acid Lysine at position 86 (Lys86) in the chain. There are two altered (mutant) forms of the protein, one with Arginine, the other with Glutamic Acid, at position 86 (instead of Lysine). Which of the 2 mutant forms of the protein is most likely to retain the functional activity and conformation of the normal form? Why? This figure from a different textbook shows how interaction between amino acid R groups can stabilize the active folded conformation of a protein (tertiary structure). Identify each of the amino acids whose R groups are shown in the diagram. 5. 5. A. Only one amino acid has no (zero) asymmetric carbon atom and therefore cannot exist as two enantiomers (i.e. it does not exhibit the property of stereoisomerism). Which amino acid is it? B. Two amino acids have a second asymmetric carbon atom in their R-group (i.e. in addition to the asymmetric alpha-carbon). Which two are they? 2 of 3 Bio 20A Supplementary Problems for Carbon and Molecular Diversity 4/1/08 6. The graphics below from show 2 major forms of secondary structure in proteins. For all of the protein strands, indicate the direction, or structural polarity by labeling the ends "COOH" or "NH2". (These figures are similar to Fig. 3.7 in your text.) 7. This is L-DOPA, administered in the management of Parkinson's disease because it is a precursor for the neurotransmitter dopamine. Only the L enantiomer is active. a. Draw a wire frame diagram of L-DOPA and indentify the asymmetric carbon atom in the LDOPA structure. (See Table 3.2 for examples of wire frame diagrams.) b. Identify the functional groups. b. L- DOPA is synthesized in nerve cells from one of the standard amino acids. Which of the 20 do you think is the precursor for L-DOPA synthesis? 3 of 3 ...
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This note was uploaded on 04/08/2008 for the course BIO 20a taught by Professor Dalby during the Spring '08 term at UCSC.

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