Lecture 11; Energy

A molecule called cyclic adenosine monophosphate (cAMP) is derived from ATP and is an important messenger molecule in the endocrine system. To produce this molecule, you would need to _____. A. remove two phosphate groups from ATP B. add a phosphate group to ATP C. add a phosphate to ADP D. remove a phosphate group from ATP

A

Individuals with the genetic disease phenylketonuria (PKU) are lacking 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 is toxic to the central nervous system, causing serious problems for the individual. Which of the following would be a reasonable management for this disease? A. Severely limit the amount of protein in the diet to avoid phenylalanine B. Increase the amount of protein in the diet to provide other amino acids that the body can metabolize C. Eat a normal diet and take tyrosine supplements D. Increase the protein in the diet in an attempt to stimulate enzyme production by increasing substrate concentration

A

Maltose is a disaccharide. Suppose someone had a hypothetical "maltose intolerance." Based on what you know about lactose intolerance, what would that mean? A. The person lacks the enzyme to break down maltose in the small intestines B. The person's cells cannot utilize maltose C. The person is allergic to maltose D. The person's enzymes accelerate the breakdown of maltose, which overloads the blood with sugar

A

The enzyme lactase ______. A. facilitates the breakdown of lactose B. raises the energy required to breakdown lactose C. catalyzes the bonding of glucose and galactose to form lactose D. is overactive in people with a lactose intolerance

A

The hydrolysis of ATP is coupled to all of the following except _____. A. osmosis B. active transport of amino acids across a membrane C. contraction of the protein microfilaments in muscle cells D. establishing a difference in electrical charge across a membrane

A

The hypothetical biochemical reaction A+B--> C+D requires 7.2 kcal/mole of energy to proceed. Could this reaction be coupled with the reaction ATP --> ADP + P (which releases 7.2 kcal/mole of energy)? A. No, because some of the energy liberated in the reaction involving ATP is released as heat B. Yes, the reaction involving ATP produces more energy when coupled with another reaction

A

What kind of reaction will occur spontaneously? A. exergonic reactions B. endergonic reactions C. inorganic reactions D. all biological reactions E. organic reactions

A

Which of the following is the most critical in determining enzyme function? A. the shape of the active site B. its overall shape C. its entire amino acid sequence D. its size

A

Which of the following might denature (change the shape) and prevent the functioning of an enzyme? A. extreme heat B. a decrease in substrate concentration C. placing the enzyme in a neutral pH D. an increase in enzyme concentration

A

Which of the following statements about ATP is false? A. The reaction ATP--> ADP + P is an endergonic reaction B. ATP serves as a main energy source inside cells C. ATP drives an endergonic reaction by transferring a phosphate group to another molecule D. The reaction ATP---> ADP + P is coupled with endergonic reactions in cells

A

Which of the following statements about enzymes is true? A. Many enzymes utilize cofactors such as vitamins or metal ions B. They increase the activation energy required for chemical reactions to proceed C. They are not reused D. The allosteric site of an enzyme has a shape that is specific for its given substrate

A

A ripped piece of paper will never spontaneously repair itself. The law of thermodynamics that explains why this is so is the ______ law of thermodynamics. A. fourth B. second C. third D. first

B

According to the first and second laws of thermodynamics, what happens if the entropy in the universe increases? A. Energy has been created B. A transformation of energy has occured C. Energy has been destroyed D. Order has increased in systems

B

Competitive and noncompetitive enzyme inhibitors differ with respect to ______. A. their energies of activation B. the location on the enzyme to which they bind C. their binding affinities D. their pH

B

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? A. Humans would no longer be able to harvest solar energy B. Oxygen levels would drop C. Carbon dioxide levels would drop D. There would not be enough water available

B

People with high cholesterol levels often take drugs in an attempt to lower their cholesterol levels. One such drug is Lipitor. How does that drug work? A. It prevents cholesterol from being absorbed in the small intestine B. It acts as a competitive inhibitor by binding to the active site of enzymes that normally produce cholesterol C. It increases the activation energy of the enzymes needed to produce cholesterol D. It enhances the activity of enzymes that help break down cholesterol in the body

B

The drug Zocor is a statin that inhibits the production of cholesterol in the body. Although the drug can lower cholesterol levels, when a person stops taking the drug, the cholesterol level typically elevates again. The most likely reason for this is that Zocor ______. A. acts as a competitive inhibitor to the enzymes that produce cholesterol, and when the drug is no longer taken, the enzyme resumes functioning to produce cholesterol B. acts as an allosteric regulator C. causes a permanent change to the shape of the enzymes that produce cholesterol so that their function in completely impaired D. increases the activation energy of the enzyme needed to produce cholesterol

B

The substrate for the enzyme lactase is _____. A. galactose B. lactose C. lactase D. glucose

B

Which of the following statements about allosteric enzymes is false? A. Their activity can be increased when the substrate binds the enzyme B. Their activity can be increased when the product binds the enzyme C. Their activity can be reduced when the product binds the enzyme D. The inhibition of allosteric enzymes is reversible

B

Which organic molecule is sometimes required for the activity of certain enzymes? A. an accessory enzyme B. a coenzyme C. a functional group D. an allosteric enzyme

B

According to the laws of thermodynamics, which of the following is impossible? A. creation of a system that couples an endergonic reaction to an exergonic reaction B. creation of an isolated system whose entropy decreases C. creation of a system that is 100% energy efficient D. creation of a system that requires a catalyst

C

Metabolism is _______. A. the sum of all the enzymes a cell contains B. the sum of all the ATP a cell contains C. the sum of all the chemical reactions that a cell carries out D. the sum of all the energy a cell uses

C

Shivering when you are cold can be helpful because ___ A. it creates a lot of new ATP that can be used in reactions in the cells to generate heat B. it decreases entropy in the cells C. it involves energy conversions in the muscles that generate heat D. it distracts your brain from processing the fact that you are cold

C

When energy changes from one form to another, some of the energy that can be used to do work is always lost. The loss of this energy is mostly in the form of _____. A. light energy B. kinetic energy C. heat D. potential energy

C

Which of the following statements about energy conversions is true? A. They are 100% efficient B. They make systems more ordered C. They generate heat D. They decrease entropy

C

Which of the following statements about energy s true? A. Energy conversions decrease entropy B. Energy can be destroyed C. Energy cannot be created D. Energy can be converted from one type to another with near 100% efficiency.

C

Which of the following statements represents a violation of the laws of thermodynamics? A. Energy conversions produce heat B. Energy cannot be created C. Entropy decreases over time D. Energy cannot be destroyed

C

Which statement concerning the following chemical reaction is false? ADP + P + energy --> ATP A. Some of the energy used to combine ADP and P into ATP is lost as heat B. This is an endergonic reaction C. This is an exergonic reaction D. The product of the reaction contains more energy than the reactants

C

A deficiency of B vitamins in your diet might cause ____. A. an increase in activation energy needed to initiate reactions B. allosteric inhibition of enzymes C. a change in the shape of your enzymes D. a lack of coenzymes needed by cells

D

A lack of solar energy would ultimately affect all living things. However, the first organism to be affected would be ______ A. animals B. bacteria C. fungi D. plants

D

The inhibitor of an enzyme is frequently a molecule that is produced at the end of a biochemical pathway in a cell. This inhibitor binds to the inhibitor site on an enzyme, causing a change in the shape of the active site enzyme. This prevents the normal substrate from binding to the active site. What process does this describe? A. kinetic feedback B. reaction coupling C. inactive control D. allosteric regulation

D

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 ____. A. activation B. inhibition C. denaturation D. allosteric regulation

D

What is the importance of coupled reactions A. Coupled reactions allow endergonic reactions to drive exergonic reactions B. Coupled reactions turn potential energy into kinetic energy C. Coupled reactions violate the second law of thermodynamics D. Coupled reactions allow exergonic reactions to drive endergonic reactions

D

When a high-energy bond of ATP is broken, what happens to the released energy? A. It converts inorganic phosphates into energy molecules B. It polarizes the cell C. It is lost as light energy D. It drives endergonic reactions in the cell

D

When bonding a phosphate group to ADP _______. A. Energy will be released B. Water will be needed C. The shape of the ribose sugar will change D. Energy will be consumed

D

Which of the following is a characteristic of competitive inhibition? A. It increases the amount of substrate available B. It increases the activity of an enzyme C. It decreases the amount of substrate available D. It decreases the activity of an enzyme

D

Which of the following is an example of kinetic energy? A. water held behind a dam B. a high concentration of Na+ on the outside of a cell membrane C. a lump of coal D. water turning a water wheel

D

Which of the following statements about enzymes is true A. Enzymes increase the activation energy needed to initiate a chemical reaction B. Enzymes force chemical reactions that would not otherwise occur without enzyme assistance C. Enzymes change their shape after participating in chemical reactions and cannot be used again D. Enzymes are critical for the regulation of important metabolic pathways

D

Which of the following statements about enzymes is true? A. One enzyme will work on many different substrate molecules to produce many different products B. They decelerate the rate of chemical reactions C. At their fastest speed, they can carry out hundreds of chemical transformations per hour D. Many activities in living organisms require multiple enzymes

D

Many types of "perpetual motion machines" have been invented, but none has worked. An example of a simple perpetual motion machine might be as follows: a battery is hooked up to an electrical engine, causing the engine to turn a generator, which recharges the battery. In theory, the machine could be turned on and then run forever; however, in reality it will not. Why? A. A battery can hold a charge for only so long B. Energy is being destroyed as it moves through the generator; thus, the battery will eventually run out of energy C. Eventually the generator would wear out D. Some of the energy will be lost in all the energy transformations; thus, the battery will eventually run down

DD