Biology Chapter 8 Flashcards

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Questions and Answers

What statement best explains the difference in how pH affects the function of this enzyme?

The enzyme is adapted for low pH but is denatured at neutral pH, leaving it nonfunctional.

Which of the following statements about the active site of an enzyme is correct?

The active site is always external to the enzyme.

The active site may resemble a groove or pocket in the surface of a protein into which the substrate fits. (correct)

The active site is the same for all enzymes.

The active site is located in the cytoplasm.

Which of the following is true regarding metabolic pathways?

They are always linear.

They consist of a series of reactions, each catalyzed by a different enzyme. (correct)

They only happen in the presence of oxygen.

They consist of a single reaction.

Which of the following statements about enzyme function is correct?

Enzymes can lower the activation energy of reactions, but they cannot change the equilibrium point because they cannot change the net energy output. Signup and view all the answers

The process of stabilizing the structure of an enzyme in its active form by the binding of a molecule is an example of __________.

allosteric regulation Signup and view all the answers

Which of the following is changed by the presence of an enzyme in a reaction?

The activation energy Signup and view all the answers

If the entropy of a living organism is decreasing, which of the following is most likely to be occurring simultaneously?

Energy input into the organism must be occurring to drive the decrease in entropy. Signup and view all the answers

Which of the following statements accurately defines energy coupling?

Exergonic reactions drive endergonic reactions. Signup and view all the answers

ATP allosterically inhibits enzymes in ATP-producing pathways. The result of this is called __________.

feedback inhibition Signup and view all the answers

Which of the following statements about enzymes is true?

Enzymes speed up the rate of the reaction without changing the ΔG for the reaction. Signup and view all the answers

Which of these statements about enzyme inhibitors is true?

The action of competitive inhibitors may be reversible or irreversible. Signup and view all the answers

How does ATP drive transport work inside a cell?

By phosphorylating a transport protein. Signup and view all the answers

How does ATP drive mechanical work inside a cell?

By binding to motor proteins. Signup and view all the answers

Cells use ATP constantly, but ATP is considered a renewable resource. What process makes this possible?

ATP can be regenerated by the addition of a phosphate group to ADP. Signup and view all the answers

Which of the following reactions would be endergonic?

Glucose + fructose → sucrose Signup and view all the answers

Which of the following correctly states the relationship between anabolic and catabolic pathways?

Anabolic pathways synthesize more complex organic molecules using the energy derived from catabolic pathways. Signup and view all the answers

Enzyme activity is affected by pH because __________.

high or low pH may disrupt hydrogen bonding or ionic interactions and thus change the shape of the active site. Signup and view all the answers

What best characterizes the role of ATP in cellular metabolism?

The free energy released by ATP hydrolysis that may be coupled to an endergonic process via the formation of a phosphorylated intermediate. Signup and view all the answers

Which of the following statements is correct regarding kinetic and potential energy?

Kinetic energy is associated with the relative motion of objects, and potential energy is the energy that matter possesses because of its location or structure. Signup and view all the answers

An exergonic (spontaneous) reaction is a chemical reaction that __________.

releases energy when proceeding in the forward direction. Signup and view all the answers

Which of the following states the relevance of the first law of thermodynamics to biology?

Energy can be freely transformed among different forms as long as the total energy is conserved. Signup and view all the answers

Which of the following statements is correct regarding competitive and noncompetitive enzyme inhibitors?

Competitive inhibitors bind to the active site of an enzyme while noncompetitive inhibitors bind to an enzyme away from the active site. Signup and view all the answers

Which of the following statements is correct regarding ATP?

The energy in an ATP molecule is released through hydrolysis of one of the phosphate groups. Signup and view all the answers

What would the value of ΔS be for a chemical reaction in which a molecule is broken down into smaller components?

Positive Signup and view all the answers

Which of the following statements correctly describes cofactors and coenzymes?

Both are nonprotein enzyme helpers; but most cofactors are metal ions, and coenzymes are organic molecules that are a specific type of cofactor. Signup and view all the answers

As ATP begins to build up in a cell, metabolism slows down. How does this happen?

ATP acts as an allosteric inhibitor to many of the enzymes involved in metabolism, thus slowing their function. Signup and view all the answers

An exergonic reaction free energy, and an endergonic reaction free energy.

releases; absorbs Signup and view all the answers

At low temperatures, a particular enzyme catalyzes a reaction, but at a slow rate. At high temperatures, the enzyme is completely inactive. What statement best explains the difference in how temperature affects the function of this enzyme?

At low temperatures, there is not enough free energy for the enzyme to function at a high rate, and at high temperatures, the enzyme is denatured, leaving it nonfunctional. Signup and view all the answers

In general, the hydrolysis of ATP drives cellular work by __________.

releasing free energy that can be coupled to other reactions. Signup and view all the answers

Which of the following is an example of the second law of thermodynamics as it applies to biological reactions?

The aerobic respiration of one molecule of glucose produces six molecules each of carbon dioxide and water. Signup and view all the answers

Study Notes

Enzyme Function and Regulation

Enzymes can be highly specific to pH levels, functioning optimally at low pH while being denatured and inactive at neutral pH.
Active sites of enzymes typically form a groove or pocket that accommodates substrates for reaction.
Metabolic pathways involve multiple steps, with each step catalyzed by a distinct enzyme.
Enzymes reduce activation energy needed for reactions but do not alter the equilibrium or net energy output.
Allosteric regulation stabilizes enzymes in their active form through molecular binding.
The presence of an enzyme specifically lowers the activation energy of chemical reactions.

Energy and Metabolism

Decreasing entropy in an organism requires energy input to counterbalance the natural tendency towards disorder.
Energy coupling refers to the process where exergonic reactions supply energy to drive endergonic reactions.
ATP can inhibit enzymes in pathways that produce ATP, leading to feedback inhibition, which regulates metabolic flow.
Enzymes increase reaction rates without changing the Gibbs free energy (ΔG) of the reaction context.

Enzyme Inhibition and Cofactors

Enzyme inhibitors can be categorized as competitive (binding active sites) or noncompetitive (binding elsewhere), influencing enzyme activity.
Hydrolysis of ATP releases energy by breaking down phosphate groups, driving cellular processes.
ATP can be regenerated from ADP by adding a phosphate group, maintaining its status as a renewable energy resource.
Coenzymes and cofactors aid enzyme function, with coenzymes being organic molecules and most cofactors being metal ions.

Thermodynamics in Biological Reactions

Kinetic energy reflects the movement of objects, while potential energy is linked to an object's position or structure.
An exergonic reaction is characterized by the release of energy, while an endergonic reaction absorbs energy.
The first law of thermodynamics emphasizes that energy can transform across forms without loss, preserving the total energy.
Examples of the second law of thermodynamics include the production of byproducts such as carbon dioxide and water in aerobic respiration.

Temperature Effects on Enzyme Activity

Enzymes may function slowly at low temperatures due to insufficient free energy; however, at high temperatures, they can become denatured and nonfunctional.
The hydrolysis of ATP acts as a driving force in cellular work by releasing free energy that is coupled to other biochemical reactions.

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Explore key concepts from Biology Chapter 8 with these flashcards. Test your understanding of enzyme function and the effects of pH on enzyme activity. Perfect for quick reviews and exam preparation.