BIOL 102 Lecture Notes - Lecture 9: Competitive Inhibition, Glycolysis, Pyruvic Acid

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pinkgoldfish355

25 Jun 2016

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Investment of atp to activate the sugar, followed by splitting c6 into 2x c3 o oxidation of c3 giving nadd + h and atp followed by recovery of initial atp investment: phosphate gets added to glucose o traps it in the cell because of negative charge, hexokinase turns it into g6p, and so on through a chain of enzyme assisted reactions, energy harvesting reactions occur when the c3 compounds are oxidized, reducing nad+ Citric acid cycle and electron transport chain: after glycolysis, the pyruvate is oxidized to acetyl coa o co2 released, glycolysis occurs in the cytoplasm, the citric acid cycle in the mitochondrial matrix o electron transport chain in the inner mitochondrial membrane, citric acid cycle o completely oxidized the 2 c acetyl group to 2 co2 molecules with dehydrogenase o formation of atp is the only step that isn"t oxidation o final product is 3 nadh, 1 fadh2, 1 atp.

Related Questions

Explain how the following mechanisms regulate enzyme activity.

Part A

Covalent modification

a)The product of a series of reactions acts as an inhibitor for an earlier reaction.

b)Hormones control the synthesis of enzymes.

c)A regulator binds to the enzyme at a site other than the active site. This binding changes the shape of the enzyme and alters the catalytic ability of the enzyme.

d)An inhibitor binds reversibly to the enzymesubstrate complex, blocking the binding of the second substrate to the active site.

e)The activity of an enzyme is influenced by the addition or removal of a group that is covalently bonded to the enzyme.

f)An inhibitor forms covalent bonds to the active site, permanently blocking it.

Part B

Genetic control

a)The product of a series of reactions acts as an inhibitor for an earlier reaction.

b)Hormones control the synthesis of enzymes.

c)A regulator binds to the enzyme at a site other than the active site. This binding changes the shape of the enzyme and alters the catalytic ability of the enzyme.

d)An inhibitor binds reversibly to the enzymesubstrate complex, blocking the binding of the second substrate to the active site.

e)The activity of an enzyme is influenced by the addition or removal of a group that is covalently bonded to the enzyme.

f)An inhibitor forms covalent bonds to the active site, permanently blocking it

Part C

Allosteric regulation

a)The product of a series of reactions acts as an inhibitor for an earlier reaction.

b)Hormones control the synthesis of enzymes.

c)A regulator binds to the enzyme at a site other than the active site. This binding changes the shape of the enzyme and alters the catalytic ability of the enzyme.

d)An inhibitor binds reversibly to the enzymesubstrate complex, blocking the binding of the second substrate to the active site.

e)The activity of an enzyme is influenced by the addition or removal of a group that is covalently bonded to the enzyme.

f)An inhibitor forms covalent bonds to the active site, permanently blocking it.

Part D

Feedback inhibition

a)The product of a series of reactions acts as an inhibitor for an earlier reaction.

b)Hormones control the synthesis of enzymes.

c)A regulator binds to the enzyme at a site other than the active site. This binding changes the shape of the enzyme and alters the catalytic ability of the enzyme.

d)An inhibitor binds reversibly to the enzymesubstrate complex, blocking the binding of the second substrate to the active site.

e)The activity of an enzyme is influenced by the addition or removal of a group that is covalently bonded to the enzyme.

f)An inhibitor forms covalent bonds to the active site, permanently blocking it

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?

3) The hydrolysis of sucrose to glucose and fructose is exergonic. However, if you dissolve sucrose in water and keep the solution overnight at room temperature, there is no detectable conversion to glucose and fructose. Why?

Select one:

a. The change in free energy of the reaction is negative.

b. The activation energy of the reaction is high.

c. The free energy of the products is higher than the free energy of the reactants.

d. This is a condensation reaction.

e. The change in free energy of the reaction is positive.

5) Competitive inhibition differs from non-competitive inhibition in that the ___1___ site is where we see competitive inhibition, while the non-competitive inhibitor __2___.

1. a. allosteric b. non-active c. active d. hydrophillic e. hydrophobic

2.
a. binds to the active site, thus blocking it
b. binds outside the active site, changing the shape of the enzyme
c. binds outside the active site, and blocks the active site

6) Phosphofructokinase is an enzyme, and as such it __1___ of the reaction. It is part of glycolysis, and is an example of an enzyme controlled by inhibition, as high levels of citrate (an intermediate further down the catabolic pathway) turns the enzyme off
(1)Select one:
a. lowers activation energy
b. lowers the ÎG
c. raises the Free Energy
(2)Select one
a. non-competitivenegative feedback
b. irreversible competitivereversible competitive.

15)The reactions in the pathways of glycolysis and the citric acid cycle harvest the high-energy electrons stored in glucose. Therefore, these pathways _______________.

Select one:

a. take place in animal cells, but not in plant cells
b. are catabolic pathways
c. are anabolic pathways
d. involve the reduction of glucose and its metabolic intermediates

21) In an exergonic chemical reaction, the products have less free energy than the reactants (-ÎG). Endergonic reactions require an input of energy (+ÎG). The addition of starting materials and the removal of end products prevent metabolism from reaching final equilibrium. Instead, the cell exists in a state of dynamic equilibrium.

Select one:
True
False

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BIOL 102 Lecture Notes - Lecture 9: Competitive Inhibition, Glycolysis, Pyruvic Acid

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