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CHM 105 - Test 3 Review - Answers
1. What is a peptide linkage?
The bond that links amino acids in a peptide. Between the O=C and the N of
the amide formed.
2. A tetrapeptide contains 4 (#) amino acids.
3. The amino acid at right is in its D configuration.
4. An ion having both a positive and negative charge is a zwitterion.
5. To which of the four classes of amino acid does cysteine belong? Cysteine is a polar amino acid.
6. Draw the tripeptide: alanine–lysine–aspartic acid. What type of bond links the amino acids? Draw an arrow to this bond.
Two drawings of the tripeptide.
Peptide Bond
7. What are the four levels of protein structure?
What level is given for the tripeptide
above?Primary, Secondary, Tertiary,
+
H3N
Quaternary (get details from notes).
Primary
8. What is denaturation of protein? What can
cause this to happen? Is it permanent? Change
O
O
CH C N CH C N CH CO2
CH3 H CH2 H CH2
CH2
CO2H
CH2
CH2
NH2
OH
H
N
+
H3 N
O
O
N
H
O
O
O
NH2
from native structure. Heat, etc. . . (see notes)
Sometimes permanent but not always.
9. What is the function of a transport protein? Give an example.
Serves as a carrier. Example: Hemoglobin
carries oxygen.
10. Which of the following are macromolecules? proteins and carbohydrates but not lipids
11. What is the net charge on cysteine, pI=5.1, when the pH=6.3? negative Which way will it move during
electrophoresis? Toward the positive electrode.
12. The names of enzymes often identify the substrate and then end with -ase (as in lactase breaks down lactose)
13. An enzyme that will catalyze the reaction of only one molecule has absolute specificity.
14. The sit on the enzyme where reaction occurs is known as the active site.
15. These substances bind to the enzyme and interfere with the reaction. inhibitors
16. Two main categories of nucleic acids. (full names) Ribonucleic Acid Deoxyribonucleic acid
Name the three subcategories. Messenger RNA; Transfer RNA; Ribosomal RNA
17. What are the building blocks of nucleosides? Base and Sugar
18. Give the name and type of base shown at right. Guanine, Purine
19. What is the anticodon for UUC? For what does this code? AAG; Phe
20. DNA is sometimes made from RNA by retro viruses. This process is called reverse transcription.
21. Nucleic acids are synthesized from their 5’ end to their 3’ end.
22. Define: antiparallel, termination code, enzyme, frame shift mutaion. See Your Notes or book.
23. Give two other names for the tricarboxylic acid (TCA) cycle. Krebs Cycle; Citric acid cycle
24. Glycolysis begins with glucose and ends at pyruvate.
25. What organelle produces most of the cell’s ATP? By what pathway(s)? Mitochondian; Electron Transport
(Oxidative Phosphorylation)
The conversion of glucose to CO2 yields approximately 36 ATP.
Each FADH 2 yields approximately 2 ATP in oxidative phosphorylation.
During fasting (starvation) our bodies produce glucose for the brain (organ) by a process called gluconeogenesis.
Proteins are synthesized at the ribosome(organelle) from the amino end to the carboxyl end.
Write the complimentary strand for dA-C-G-C-A-A-G. T-G-C-G-T-T-dC
Give an example of the strand above with a point mutation. dA-C-G-C-T-A-G One base is different.
What are most likely outcomes for the cell if an uncorrected mutation occurs in the DNA?
1. No effect — error in a noncoding region of the DNA; synonym code; code for very similar amino acid.
2. Cell dies — effect is major enough (crucial protein doesn’t function) that the cell cannot survive.
3. Cell grows abnormally — rapid division of cells creates a tumor.
33. During glycolysis fructose-1,6-diphosphate is broken into these two 3 carbon phosphates glyceraldehyde-3phosphate and dihydroxyacetonephosphate which are then converted to pyruvate. Without oxygen (anaerobic),
the pyruvate is converted into lactate (lactic acid) to recycle the reduced coenzyme NADH back into the oxidized
coenzyme NAD+ so that glycolysis may continue.
34. How many acetylCoA’s are produced from a 12 carbon fatty acid? 6 By what pathway? fatty acid spiral or
β-oxidation Producing the equivalent of how many ATP? 23 = 5times around spiral X 5ATP – 2ATP
26.
27.
28.
29.
30.
31.
32.
activation
35. Which stage of catabolism produces the bulk of the CO2? ...the H2O? ...the ATP? All are Stage 3
36. Stage one of catabolism is commonly called digestion. For fats this occurs in the intestine forming fatty
glycerol.
37. Which pathway, cycle, or spiral produces a GTP that is converted to an ATP? The Krebs cycle.
acids and