(BIOL) Exam 4 Review

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

Water at the top of a dam has potential energy; water falling through a dam has kinetic energy. The moving water performs work by moving the blades of turbines in the dam to generate electricity.

Which of the following is a chemical reaction?

The formation of a covalent bond between two amino acids

_{^{*Chemical reactions involve the making and breaking of chemical bonds, leading to changes in the composition of matter. Ice melting changes the state of water rather than the composition of water, and hydrogen bonds do not change the composition of the molecules involved. Chemical reactions cannot create or destroy atoms but can only rearrange (redistribute) the electrons among them.}}

Chemical equilibrium is reached when

the forward and reverse reactions occur at the same rate

Which of the following is the strongest evidence that protein structure and function are correlated?

Denatured (unfolded) proteins do not function normally.

Energy is observed in two basic forms: potential and kinetic. Which of the following correctly matches these forms with a source of energy?

• kinetic energy with the energy related to the height of a bird above the ground

• potential energy with the covalent bonds of a sugar molecule

• kinetic energy with the energy associated with a gradient of ions across a membrane

• potential energy with the heat released from a living organism

• potential energy with the motion of individual molecules

potential energy with the covalent bonds of a sugar molecule

Which of these is exhibiting kinetic energy?

a space station orbiting Earth

"Conservation of energy" refers to the fact that _____

energy cannot be created or destroyed but can be converted from one form to another

Chemical energy is a form of _____ energy

potential

In your body, what process converts the chemical energy found in glucose into the chemical energy found in ATP?

cellular respiration

Which of these are by-products of cellular respiration?

heat, carbon dioxide, and water

Which of the following examples describes a type of potential rather than kinetic energy?

a sucrose molecule

Which of the following statements about equilibrium of chemical reactions is correct?

A reaction that is at equilibrium is not capable of doing any work.

The process of cellular respiration, which converts simple sugars such as glucose into CO₂ and water, is an example of __________.

a catabolic pathway

Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as _______ is to _______.

exergonic; endergonic

Which of the following statements about ATP (adenosine triphosphate) is correct?

• The hydrolysis of ATP can supply energy needed for catabolic pathways.

• Almost all of the free energy released in the hydrolysis of ATP is released as heat.

• The energy release on hydrolysis of ATP is the result of breaking a high-energy bond.

• The hydrolysis of ATP is an endergonic process.

• The cycling between ATP and ADP + Pi provides an energy coupling between catabolic and anabolic pathways.

The cycling between ATP and ADP + Pi provides an energy coupling between catabolic and anabolic pathways.

What type of reaction breaks the bonds that join the phosphate groups in an ATP molecule?

• dehydration decomposition

• hydrolysis

• dehydration synthesis

• entropic

• anabolism

hydrolysis

How does the phosphorylation of glutamic acid (Glu) provide energy for the rest of the reaction to occur?

The addition of a phosphate to Glu forms a phosphorylated intermediate with more free energy than Glu. The ammonia can thus displace the phosphate in an exergonic reaction

A chemical reaction occurs between the amino acids alanine (Ala) and glycine (Gly), forming the compound alanylglycine. The simple conversion reaction of alanine and glycine into this compound is endergonic, with a ∆G of 6.9 kcal/mol. Therefore, it requires ATP hydrolysis to drive the nonspontaneous reaction. Calculate the free energy change for the whole process, applying what you know about ATP hydrolysis

∆G = -0.4 kcal/mol

Which of these statements best describes the overall progress of a reaction?

The breaking of bonds requires an input of energy, and the formation of new bonds releases energy.

An enzyme _____

is an organic catalyst

What name is given to the reactants in an enzymatically catalyzed reaction?

substrate

As a result of its involvement in a reaction, an enzyme _____

is unchanged

If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to

add more of the enzyme.

Some bacteria are metabolically active in hot springs because

their enzymes have high optimal temperatures

You have added an irreversible inhibitor to a sample of enzyme and substrate. At this point, the reaction has stopped completely. What can you do to regain the activity of the enzyme?

Removing the inhibitor and adding more enzyme

You have an enzymatic reaction proceeding at the optimum pH and optimum temperature. You add a competitive inhibitor to the reaction and notice that the reaction slows down. What can you do to speed the reaction up again?

Add more substrate; it will outcompete the inhibitor and increase the reaction rate

The binding of a compound to an enzyme is observed to slow down or stop the rate of the reaction catalyzed by the enzyme. Increasing the substrate concentration reduces the inhibitory effects of this compound. Which of the following could account for this observation?

the compound is a competitive inhibitor

Which of the following statements about feedback inhibition of a metabolic pathway is correct?

• The final product of a metabolic pathway is usually the compound that regulates the pathway.

• The enzyme that is regulated by feedback inhibition is usually the last enzyme in the metabolic pathway.

• The products of the pathway become the reactants for a different reaction, and thus products are unable to accumulate.

• Accumulation of the product of the pathway increases further formation of that product.

• The compound that regulates the pathway acts as a competitive inhibitor or a positive allosteric regulator.

The final product of a metabolic pathway is usually the compound that regulates the pathway

Which of the following would be unlikely to contribute to the substrate specificity of an enzyme?

• a similar shape exists between a pocket on the surface of the enzyme and a functional group on the substrate

• the enzyme has the ability to change its configuration in response to the substrate binding

• a hydrophobic group on the substrate interacts with several hydrophobic amino acids on the enzyme

• a positive charge on the substrate is attracted to a negative charge in the active site of the enzyme

• the enzyme has an allosteric regulatory site

the enzyme has an allosteric regulatory site - _{^{The allosteric site is distinct from the active site and does not affect the substrate specificity of the enzyme.}}