Chapter 3 (Quiz)

Oxidation is the process by which oxygen atoms are added to a target molecule. Generally, the atom that is oxidized will experience which of the following with respect to the electrons in its outer shell?

A net loss

Activated carriers are small molecules that can diffuse rapidly and are used to drive biosynthetic reactions in the cell. Their energy is stored in a readily transferable form, such as high-energy electrons or chemical groups. Which of the molecules shown here are widely used activated carriers in cells? (There may be more than one correct answer): A. FADH2 B. NADH C. NADPH D. ATP

A, B, C, & D

ΔG° indicates the change in the standard free energy as a reactant is converted to product. Given what you know about these values, which reaction below is the most favorable? A. ADP + Pi → ATP - ΔG° = +7.3 kcal/mole B. glucose 1-phosphate → glucose 6-phosphate- ΔG° = -1.7 kcal/mole C. glucose + fructose → sucrose - ΔG° = +5.5 kcal/mole D. glucose → CO2 + H2O - ΔG° = -686 kcal/mole

D

An enzyme facilitates a reaction by

Lowering the activation energy of the reaction

The rate at which an enzyme will encounter a substrate depends on

The concentration of the substrate in the cell

Consider two molecules that associate with each other through hydrogen bonds. In this association, the larger the equilibrium constant, K:

The more tightly the two molecules will bind

Energetically favorable reactions are those that:

decrease the free energy of a system

If proteins A and B have complementary surfaces, they may interact to form the dimeric complex AB. Which of the following is the correct way to calculate the equilibrium constant for the association between A and B?

kon/koff = K or K = [AB]/[A][B]

When an enzyme is functioning at Vmax, the rate of the reaction is limited by:

the rate at which the enzyme can convert bound substrate to product and release the product.

Any reaction A ⇔ B is at equilibrium when

∆G = 0

If the equilibrium constant (K) for the binding of molecule A to molecule B is K = 1000, and for the binding of molecule A to C is K = 20000, which molecule has a weaker binding affinity for A?

B

Cells use anabolic reactions to build required molecules, like proteins and nuclei acids. These reactions are unfavorable so cells use intermediate steps to provide the energy needed. Of the following examples, which is NOT an intermediate molecule used in cells? ATP NADP FADH2 CO2

CO2

A common means of providing energy to an energetically unfavorable reaction in a cell is by

Coupling of ATP hydrolysis to the reaction

In thermodynamics, what does the term "free energy" refer to?

Energy that can be harnessed to do work or drive chemical reactions

Catalysts are molecules that lower the activation energy for a given reaction. Cells produce their own catalysts properly called

Enzymes

After an enzyme catalyzes a reaction, the enzyme will not be able to perform additional reactions because it will be permanently altered.

False

Most of the energy available for use by cells and organisms on earth is obtained through:

Photosynthesis

The potential energy stored in the high-energy bonds found in complex compounds is commonly harnessed when the bonds are split by the addition of ____________ in a process called _____________.

Water, hydrolysis

Two molecules will bind to each other by means of noncovalent bonds if the ΔG° of the interaction is:

negative (the free energy of the product is lower than the sum of the free energies of the unbound partners).