Bio 181 chapters 8 and 9

A + B → C + D

A gives up electrons. B accepts electrons.

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.

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.

Drugs known as uncouplers facilitate diffusion of protons across a membrane. With an uncoupler, what will happen to ATP synthesis and oxygen consumption if the rates of glycolysis and the citric acid cycle stay the same?

ATP synthesis will decrease. Oxygen consumption will stay the same.

Oxidative phosphorylation

About 26-28 ATP

Pyruvate oxidation

Acetyl CoA and CO2

Ae- + B → A + Be-

Ae- is oxidized. B is reduced.

Regarding enzymes, which are correct?

After catalysis, the enzyme returns to its original form. The enzyme changes shape during catalysis. When an enzyme binds to its substrate molecule(s), a temporary enzyme-substrate complex is formed.

Glucose is the primary fuel for cellular respiration. Which of the following molecules can also be used by cellular respiration to generate ATP?

Amino acids Glycerol Fatty acids

Regarding substrate phosphorylation, which are correct?

An enzyme catalyzes the formation of ATP by direct transfer of a phosphate group to ADP from an intermediate molecule. Occurs during the glycolysis phase of respiration Occurs during the citric acid cycle

A protein is synthesized from amino acids.

Anabolic pathway

Consumes energy to synthesize a complex molecule

Anabolic pathway

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.

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

During aerobic respiration, molecular oxygen (O2) is used for which of the following purposes?

At the end of the electron transport chain to accept electrons and form H2O

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.

How does ATP drive mechanical work inside a cell?

By binding to motor proteins

How does ATP drive transport work inside a cell?

By phosphorylating a transport protein

Glucose is broken down in the presence of oxygen to carbon dioxide and water.

Catabolic pathway

Selectively increases the rate of a reaction

Catalyst

Which of the following pairs of pathways and their location in the cell is incorrectly matched?

Citric acid cycle: cytosol

What is Vioxx?

Competitive inhibitor

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.

Neither enzyme will function.

Decrease pH from 8 to 5

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.

Regarding the ATP cycle, which are correct?

Energy coupling is the use of an exergonic process to drive an endergonic one. If the ΔG of an endergonic reaction is less than the amount of energy released by ATP hydrolysis, then the two reactions can be coupled.

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.

Regarding enzymes, which are correct?

Enzymes may act on more than one substrate. The active site lowers the EA of the reaction. The enzyme changes shape during catalysis.

The primary manner in which cells manage their energy resources in order to do work is called energy coupling. Which of the following statements accurately defines energy coupling?

Exergonic reactions drive endergonic reactions.

Cells must regulate their metabolic pathways so that they do not waste resources. What is the most common mechanism that regulates cellular respiration in most cells?

Feedback inhibition of glycolysis

Fermentation by itself produces no ATP but keeps glycolysis going, which produces a small amount of ATP. How does fermentation do this?

Fermentation oxidizes NADH to NAD+, which facilitates the production of ATP in glycolysis

Glycolysis

First

Oxidative phosphorylation

Fourth

Which of the following reactions would be endergonic?

Glucose + fructose → sucrose

In which process is glucose oxidized to form two molecules of pyruvate?

Glycolysis

Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule?

Glycolysis

Most of the ATP in cellular respiration is produced by the process of chemiosmosis. How does this process produce ATP?

H+ flows across the inner mitochondrial membrane through the enzyme ATP synthase.

Regarding metabolic reactions, which are correct?

Higher G systems tend to change in such a way that they become lower G. For exergonic reactions, ΔG is negative. Exergonic reactions are spontaneous.

The rate of reaction of pepsin will decrease.

Increase pH from 1.8 to 3

The rate of reaction of trypsin will increase.

Increase pH from 6 to 7

The rate of reaction of trypsin will decrease.

Increase pH from 7.1 to 9.2

What is the role of oxygen in the electron transport chain

It is reduced to form water.

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.

Which statement correctly describes the difference between alcohol fermentation and lactic acid fermentation?

Lactic acid fermentation produces lactate, and alcohol fermentation produces ethanol.

Which of the following is true regarding metabolic pathways?

Metabolic pathways consist of a series of reactions, each catalyzed by a different enzyme.

After completion of the citric acid cycle, most of the usable energy from the original glucose molecule is in the form of __________.

NADH

During the energy payoff phase of glycolysis, __________.

NADH and ATP are produced

In what molecule(s) is the majority of the chemical energy from pyruvate transferred during the citric acid cycle?

NADH and FADH2

A new drug inhibits the action of a specific enzyme by binding to it. The drug is unaffected by changes in the concentration of the substrate. What is this drug?

Noncompetitive inhibitor Allosteric regulator

C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy

O2 accepts electrons. O2 is the oxidizing agent. Glucose is the reducing agent.

Which of the following is a correct description of the events of cellular respiration and the sequence of events in cellular respiration?

Oxidation of glucose to pyruvate; oxidation of pyruvate; oxidation of acetyl-coA; oxidative phosphorylation

All of the processes involved in cellular respiration produce ATP. Which of the following processes produces the most ATP?

Oxidative phosphorylation

In preparing pyruvate to enter the citric acid cycle, which of the following steps occurs?

Pyruvate is oxidized and decarboxylated, and the removed electrons are used to reduce an NAD+ to an NADH.

Most of the electrons removed from glucose by cellular respiration are used for which of the following processes?

Reducing NAD+ to NADH in glycolysis and the citric acid cycle AND producing a proton gradient for ATP synthesis in the mitochondria.

Pyruvate oxidation

Second

An iron railing rusts.

Spontaneous process

Which of these statements about enzyme inhibitors is true?

The action of inhibitors may be reversible or irreversible.

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

The activation energy

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

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

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.

Most of the NADH that delivers electrons to the electron transport chain comes from which of the following processes?

The citric acid cycle

Which part of the catabolism of glucose by cellular respiration requires molecular oxygen (O2) and produces CO2?

The combination of the citric acid cycle and electron transport

Which of the following metabolic pathways produce(s) the most ATP, per glucose molecule metabolized, during cellular respiration?

The electron transport chain and oxidative phosphorylation

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.

The ATP synthase in a human cell obtains energy for synthesizing ATP directly from which of the following processes?

The flow of H+ across the inner mitochondrial membrane through the ATP synthase enzyme

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.

Regarding the ATP cycle, which are correct?

The phosphorylated intermediate is more reactive than the original unphosphorylated molecule. If the ΔG of an endergonic reaction is less than the amount of energy released by ATP hydrolysis, then the two reactions can be coupled. Energy coupling is the use of an exergonic process to drive an endergonic one.

Which are correct?

The presence of the enzyme lowers EA. The red curve [2] shows the reaction with the enzyme

The energy from the electrons in NADH and FADH2 fuel what process in the electron transport chain?

The pumping of H+ across the cristae of the mitochondrion

The rate of reaction of pepsin will increase

The rate of reaction of pepsin will increase

Which are correct?

The red arrow [4] shows EA in the presence of the enzyme. The yellow arrow [5] shows that the enzyme has no effect on ΔG.

Regarding metabolic reactions, which are correct?

The ΔG of an exergonic reaction is negative. Exergonic reactions are spontaneous. The ΔG of an endergonic reaction is positive.

Citric acid cycle

Third

A small amount of ATP is made in glycolysis by which of the following processes?

Transfer of a phosphate group from a fragment of glucose to ADP by substrate-level phosphorylation

Citric acid cycle

Two ATP, six NADH and two FADH2

What is the total production of ATP, NADH, and FADH2 in the citric acid cycle from one molecule of glucose?

Two ATP, six NADH, and two FADH2

Glycolysis

Two molecules of pyruvate, two ATP, and two NADH

Regarding oxidative phosphorylation, which are correct?

Uses a proton gradient across the membrane Accounts for almost 90% of the ATP generated by respiration ATP synthase enzyme uses elctrochemical energy to add an inorganic phosphate to ADP. Produces ATP by using energy derived from the redox reactions of an electron transport chain

Which of the following statements about enzymes is true?

Which of the following statements about enzymes is true?

Releases energy by breaking down complex molecules

catabolic pathway

Sucrase speeds up the breakdown of sucrose.

catalyst

Fermentation is essentially glycolysis plus an extra step in which pyruvate is reduced to form lactate or alcohol and carbon dioxide. This last step __________.

enables the cell to recycle the reduced NADH to oxidized NAD+

The function of cellular respiration is to __________.

extract usable energy from glucose

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

feedback inhibition

During the energy investment phase of glycolysis, __________.

glucose is phosphorylated before it is split into two three-carbon molecules

In the overall process of glycolysis and cellular respiration, __________ is oxidized and __________ is reduced.

glucose; oxygen

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

A molecule becomes more oxidized when it __________.

loses an electron

Muscle tissues make lactate from pyruvate to do which of the following?

regenerate NAD+

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

releases energy when proceeding in the forward direction

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

releases; absorbs

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

releasing free energy that can be coupled to other reactions

Occurs without an overall input of energy

spontaneous process