Question 1

Phosphofructokinase is an enzyme involved in glycolysis, which is a metabolic pathway involved in ATP production. It can be allosterically regulated by both ATP and ADP. Why is regulating the activity of this enzyme important? Predict what will happen to the rate of reaction when ATP levels in the cell are high, and predict what will happen when the levels of ADP in the cell are high.

Accepted Answer

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Question 2

It has been hypothesized that, if the sun disappeared, all life would end. Other than the obvious drop in temperature, why would humans probably die if the sun suddenly stopped shining?

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Question 3

Refer to the figure below, and then answer the question that follows. 
-The figure above represents allosteric inhibition. Based on the figure, what could be done to allow the enzyme to function again?

Accepted Answer

Allosteric inhibition occurs when a product of the reaction binds to a site on the enzyme, causing a conformational change that inhibits the enzyme's activity. To allow the enzyme to function again, some of the product would need to be removed so that it no longer binds to the allosteric site and causes inhibition. Adding more enzyme or substrate would not necessarily overcome the inhibitory effect caused by the product. Removing some of the substrate could potentially reduce the rate of the reaction even further, as there would be less substrate available for the enzyme to act on.

Question 4

Would ATP be the energy currency of the cell if the phosphate groups the cell contains were not charged? Why or why not?

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Question 5

You have been asked to explain to a high school class the first law of thermodynamics and how this law affects the students' lives. Using your own words, describe the first law of thermodynamics, and give an example (other than the examples described in the chapter).

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Question 6

Explain how vitamins play a role in cellular metabolism.

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Question 7

You have been asked to explain to a high school class the second law of thermodynamics and how this law affects the students' lives. Using your own words, describe the second law of thermodynamics, and give an example (other than the examples described in the chapter).

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Question 8

Explain why it takes energy to create starch from glucose, but it does not take energy to create glucose from starch. In your explanation, describe the law of thermodynamics that explains this, and describe how.

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Question 9

Individuals with the genetic disease phenylketonuria (PKU) lack a single enzyme called phenylalanine hydroxylase, which converts the amino acid phenylalanine to the amino acid tyrosine. If this conversion does not happen, phenylalanine builds up and becomes toxic to the central nervous system, causing serious problems for the individual. The management of this disease is to avoid phenylalanine by severely limiting the amount of protein in the diet. How would this help?

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Question 10

Molecules that facilitate the work of enzymes by binding with them are ________.

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Question 11

The regulation of an enzyme's activity by means of a molecule binding to a site on the enzyme other than its active site is called ________.

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Question 12

Refer to the figure below, and then answer the question that follows. 
-The figure above represents:

Accepted Answer

The figure shows a series of enzyme-catalyzed reactions that make up a metabolic pathway. Each reaction is catalyzed by a specific enzyme, and the product of one reaction becomes the substrate for the next reaction in the pathway.

Question 13

A ________ is a set of enzymatically controlled steps that results in the completion of a product or process in an organism.

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Question 14

Explain why enzymes are involved in exergonic reactions, such as lactose breaking down into glucose and galactose, and whether these reactions can occur spontaneously.

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Question 15

A ripped piece of paper will never spontaneously repair itself. Explain the law of thermodynamics that explains why this is so.

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Question 16

A reaction that requires the input of energy to move forward is ________.

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Question 17

Refer to the figure below, and then answer the question that follows. 
-You have a job as an assistant in a morgue. You are startled (almost to death) when a corpse that recently came in suddenly sits up and remains very stiff. This muscle contraction and stiffness in a dead body is known as rigor mortis. Using your knowledge of the ADP/ATP cycle and its role in muscle contraction, explain why rigor mortis occurs.

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Quiz 6: Lifes Mainspring: an Introduction to Energy