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I have left up the previous semester's review sheet as some students find this helpful.  It will be updated 2-5 days before the exam.

Section D01 MWF: Exam 3 is : Wednesday April 23rd, 2008 (this date may be changed to the 25th)

Section Do2 T/Tr: Exam 3 is Tuesday April 29th, 2008

Biochemistry Exam 3 review sheet Spring 2008

This exam review sheet is intended to help you prepare for the exam but should not be considered your only source of study.  This is only an outline, and I have left off detailed information, so you should use your notes and text to help you prepare for the exam.  You are still responsible for any material we covered in class, whether on this sheet or not.     This lists serves only to highlight the main points.

Material will be a combination of multiple choice and short answer questions from Chapter 21 (same format of previous exams)

Chapter 21: Enzymes

  • Enzymes catalyze biological reactions
  • What types of macromolecule are enzymes?
  • Describe the mechanism of enzyme action
  • how do enzymes accelerate reactions?
  • Be familiar with the terms substrate, enzyme-substrate complex, product, active site, transition state
  • What is activation energy?  What effect do enzymes have on this?
  • what is the transition state?
  • What is an active site?  How does the substrate interact with the substrate?  What types of bonds are involved?
  • Enzymes lower activation energy for reactions
  • Enzyme specificity (Absolute or relative)--what is the difference?
  • Review note on lactose/lactase
  • Be familiar with the Lock and Key versus Induced Fit models of substrate/enzyme interaction
  • What is the difference between simples and conjugated enzymes?
  • What is a cofactor?
 
  • Metal ion, such as Mg+, Cu++, Zn++)
  • what are examples of enzymes with different metal ions?
     Be familiar with the two models of how activators work. 
    where are metal ions from in our diet?
  • Coenzyme (organic molecule, often vitamin derivatives such as NAD+ and FAD+ which are derived from vitamin B)
    what are examples of enzymes with different coenzymes?
    What do coenzymes do in a reaction?
    where are coenzymes from in our diet?
What is an apoenzyme? Holoenzyme?
Enzyme names end in –ase
Be familiar with the following general types of enzymes and what they do:
-Transferase
-Hydrolase
-Isomerase
-ligase
-oxidireductase
-lyase
Be familiar with alcohol dehydrogenase because we used this example repeatedly
Ethanol + NAD+ -à acetaldehyde + NADH + H+
requires two cofactors!
metal ion cofactor: zinc
coenzyme: NAD+
ethylene glycol -à glycolic and oxalic acids (see info on competitive inhibitors below)
  • What are factors that influence enzyme activity?
    • review graphs we discussed in class looking at the effect of pH, temp, substrate conc., enzyme conc., end product conc. on reaction rates.
    • what is meant by optimum ph? optimum temperature?
    • review your in-class handout. 
    • Be able to draw a graph given some information on these factors. 

 

Enzyme Inhibition

  • Irreversible
  • Change tertiary or quaternary structure if enzyme/permanently inactivates
  • Example: insecticides, nerve gas, penicillin, cyanide
  • How do ieach if these work (what enzyme is inactivated?)

Reversible Competitive

  • Structurally similar to natural substrate/compete with it for binding to active site
  • Examples:1.ethylene glycol is competitive inhibitor of alcohol dehydrogenase (see reaction above) and 2.sulfa drugs

Non-competitive

  • Do not resemble substrate/bind away from active site
  • Examples: heavy metal ions (lead/arsenic/mercury)

Enzyme regulation

  • review genetic control of enzyme activity.  Ex: lac operon (section D01 only)
  • Allosteric regulation
  • When is this involved? How does it work? Where does modulator/regulator bind?
  • Zymogens
  • What is a zymogen?
  • Examples: pepsinogen, trypsinogen, prothrombin, fibrinogen
  •  

Be able to answer the following questions from the end of chapter 21:

1-6, 9-12, 19-26, 29-32, 35-43, 45-47, 49-60