1[1]2._cell_chemistry

1[1]2._cell_chemistry - Biological Sciences 1A (Wheelis)...

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Biological Sciences 1A (Wheelis) Sample Exam—Cell Chemistry 1. What is the approximate age of the first cells on earth? a. 4 X 10 9 years before present (ybp) b. 3.5 X 10 9 ybp c. 3.0 X 10 9 ybp d. 2.5 X 10 9 ybp e. 5, 000 ybp 3. In the compound above, which atom is asymmetric? a. 1 b. 2 c. 3 d. 4 e. none 4. Which of the above functional groups has a net charge at neutral pH? d. all of them e. none of them O-H N-H O=O C-H (1) (2) (3) (4)
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5. Which of the above covalent bonds is polar? a. 1 b. 1 & 2 d. all of them e. none of them 6. Which of the following functional groups can alternate between protonated and unprotonated forms (depending on pH)? a. -CHO and -COOH b. -CHO and -NH 3 c. -COOH and -NH 3 d. -OH and -COOH e. -OH and -NH 3 7. Acidic pHs favor a. negatively charged carboxyl groups and positively charged amino groups b. neutral carboxyl groups and positively charged amino groups c. negatively charged carboxyl groups and neutral amino groups d. both carboxyl and amino groups neutral e. both carboxyl and amino groups positively charged 8. The ratio of protonated to unprotonated functional groups goes up when a. the pH is made more basic b. the pH is made more acidic c. the temperature rises d. all of the above e. never--each functional group has a constant ratio of protonated to unprotonated forms 9. Basic pHs favor a. negatively charged carboxyl groups and positively charged amino groups b. neutral carboxyl groups and positively charged amino groups c. negatively charged carboxyl groups and neutral amino groups d. both carboxyl and amino groups neutral e. both carboxyl and amino groups positively charged Use the following answers for questions 10-14 a. C 6 H 12 O 6 b. C 8 H 11 O 2 N c. C 35 H 38 O 10 P d. C 9 H 14 O 8 N 3 P e. C 18 H 36 O 2 10. The empirical formula for a nucleotide 11. The empirical formula for an amino acid 2
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12. The empirical formula for a fatty acid 13. The empirical formula for a sugar 14. The empirical formula for a phospholipid Use the diagrams above for questions 15-19 15. An amino acid 16. A fatty acid 17. A sterol 18. A nucleotide 19. A sugar 21. What stabilizes the secondary structure of proteins a. hydrogen bonds between the carbonyl groups and amines of the peptide backbone b. ionic and interactions among the amino acid R-groups (side chains) c. interactions among hydrophobic groups of the peptide backbone d. interactions among hydrophobic R-groups e. all of the above 3
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22. What is the repeating group in the backbone of a protein?
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1[1]2._cell_chemistry - Biological Sciences 1A (Wheelis)...

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