BIOL 100 Lecture Notes - Lecture 15: Pyruvic Acid, Cytochrome C, Acetyl-Coa

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champagnebee70

23 May 2016

School

UM Dearborn, UMD

Department

Biological Science (BIOL)

Course

BIOL 100

Professor

Adler

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Document Summary

Enzymes are regulated by their environment: changing of ph, temperature, electrolytes- the enzyme activity can be inhibited, isozymes: a different form of an enzyme (an enzyme that has similar function, but is a different form) Enzymes have a temperature where they can become denatured. Allosteric enzymes: control their activity by changing shape, they are controlled by allosteric regulators. These bind to a site other than the active site. They kind of act like a noncompetitive inhibitor. Allosteric binding will change the shape of the active site and the function of the enzyme: allosteric enzymes can have multiple active sites and often they work in co- operatively. This means that once one active site binds to a substrate, other substrates can bind more readily. It"s easier for the other ones to bind once the other is bound: these enzymes have at least 2 subunits. This binds to the substrate and has the enzymatic activity.

Related Questions

45. The catalysis mechanism used by lysozyme to break down bacterial cell walls is

acidâbase catalysis.

covalent catalysis.

metal cofactor redox catalysis.

induced strain.

unknown.

46. Competitive inhibitors of enzymes work by

fitting into the active site.

fitting into a site other than the active site.

altering the shape of the enzyme.

changing the enzyme into an inactive form.

increasing the activation energy of the enzyme-catalyzed reaction.

47. Nerve gases such as Sarin and malathion

block specific chemical transformations by inactivating specific enzymes.

have reversible effects on animals.

are proteins with a primary structure.

block the energy coupling cycle of ATP.

bond covalently to the active site of the enzyme.

48. How do competitive and noncompetitive enzyme inhibitors differ?

Competitive inhibitors bind to the active site, whereas noncompetitive inhibitors change the shape of the active site.

Competitive inhibitors have a higher energy of activation than noncompetitive inhibitors have.

They function at different pH values.

Noncompetitive enzyme inhibitors contain magnesium, whereas competitive inhibitors contain iron.

Noncompetitive enzyme inhibitors are reversible, whereas competitive inhibitors are irreversible.

amaranthwolf320

Enzyme Activity

1. Briefly explain the principle of spectrophotometry.

2. Which of the following statements is true about enzymes?(check all correct answers)

		__ enzymes act on (are specific for) one or just a fewsubstrates
		__ enzymes can be denatured (loose their tertiary/quaternarystructure and activity) by extreme conditions such as heat, high orlow pH,or presence of organic solvents
		__most enzymes are DNA
		__ enzymes are protein
		__enzymes perform best at specific conditions of temperature, pHand salt concentration 5. Which enzymes break the following macromolecules? Match the following with their correponding answers: ___ Nucleic acids A. proteases or proteinases such as pepsin ___ Cellulose B. none ___ Triglycerides C. lipases ___ Proteins D. amylases ___ Starch E. nucleases 6.Match the following enzymes totheir products. Answers ___ pepsin, trypsin and other digestive proteases A.Nucleotides ___ salivary and pancreatic amylases and other enzymes B. AminoAcids ___ lipases C. Monosaccharides ___ nucleases D. fatty acids and glycerol 7. Based on experiments, what is the effect of extremeconditions of pH and temperature (boiling tube) on enzymeactivity? 8. ATP stores energy in the form of___ ___ Chemical energy ___ Kinetic energy ___ Thermal energy ___ Activation energy 9. An allosteric site in anenzyme is____ __ the site where reactions occur __ the site that binds aregulator __ the site that binds thesubstrate __ the site that binds the product 10. Enzymes increase the rate of reactions by making thetransition state less stable. __ True __ False 11. Enzymes increase the rate of reactions by placing reactingparts of the molecule in favorable positions. __ True __ False 12. Which of the followingis a mechanism for regulation of enzymes? __ covalent modification __ feedback inhibition __ allosteric regulation __ all of the above 13. Which of the following represents a correct order of eventsin an enzyme catalytic cycle? 1.enzyme changes shape 2.substrate binds to active site 3.substrate is converted to products 4. products are released from activesite __ 1>2>3>4 __ 2>1>3>4 __ 3>2>1>4 __ 2>4>3>1

cyancicada301

Phosphofructokinase (PFK1) is a glycolytic enzyme that catalyzes the irreversible transfer of a phosphate from ATP to fructose -6-phosphate to form fructose-1, 6- bisphosphate.

fructose-6-phosphate + ATP --> fructose-1,6-bisphosphate + ADP

PFK1 is the key regulatory enzyme for glycolysis. When ATP levels are high in the cell, the cell no longer needs metabolic energy production to occur. In the case of these high energy levels, PFK1's activity is inhibited by allosteric regulation by ATP, which essentially closes the valve on the flow of carbohydrates through glycolysis.

Recall that allosteric regulators bind to a different site on the enzyme rather than the active (catalytic) site. ATP binds to the regulatory site and decreases PFK1 activity. ATP bound in the regulatory site acts as a modulator by lowering the affinity of PFK1 for its substrate, fructose-6-phosphate. AMP on the other hand, which is generated when the cell is in a low energy state binds to allosteric site and increases enzyme activity.

7. The enzyme PFK1 is an example of a non-regulatory enzyme or regulatory enzyme?

8. How is PFK regulated?

A. It is not regulated because it is a non-regulatory enzyme

B. allosteric enzyme regulation

C. covalent enzyme regulation

D. or proteolytic cleavage enzyme regulation?

9. What is the substrate and to which site on the enzyme does it bind? Which compounds are the positive and negative effectors?

10. In which conformational state would the enzyme be when negative inhibitors bind and in which conformational state would the enzyme be when positive inhibitors bind?

11. PFK1 is a heterotropic or homotropic regulatory enzyme?

12. Draw (or insert the picture from your course packet available on Canvas) the graph that corresponds to this reaction. Your graph should include the activity of PFK without bound effectors, with bound positive effector, and with bound negative effector. Label (or describe) each line to distinguish these along with which molecules are positive and negative effectors.

13. How does Vmax and K0.5 change with the positive and negative effectors?

BIOL 100 Lecture Notes - Lecture 15: Pyruvic Acid, Cytochrome C, Acetyl-Coa

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