LS 6

what is a noncompetitive inhibitor?

a molecule that binds to an allosteric site and prevents the proper functioning of an enzyme

the *blank* for an exergonic reaction is lower in the presence of a catalyst for the reaction

activation energy

the *blank* site is a specific region of an enzyme to which non-competitive inhibitors bind in order to regulate enzyme activity

allosteric

select the events that occur before bonds in the substrate are broken during an enzyme catalyzed reaction

amino acids in the enzyme must interact with the substrate; the substrate must bind the enzyme; a substrate-enzyme complex must form

select reasons why metabolic pathways are regulated

by regulating metabolic pathways, cells conserve raw materials; by regulating metabolic pathways, cells waster less energy; regulation allows cells to operate efficiently

what are competitive inhibitors?

competitive inhibitors bind to the active site of an enzyme and prevent substrates from binding

living organisms can convert the potential energy stored in chemical bonds into what other forms of energy?

electrical energy (electricity); potential energy in the bonds of new molecules; light energy; kinetic energy

a reaction that requires an input of energy is said to be a(n) *blank* reaction

endergonic or non spontaneous

what are proteins or RNA molecules that act as catalysts to speed up reactions in living organisms?

enzymes

select the characteristics of enzymes

enzymes may be used more than once in a cell; enzymes aren't changed or consumed in reactions; enzymes lower the activation energy required for new bonds to form in a chemical reaction

true or false: energy stored in the chemical bonds of a molecule can't be harvested and used to make new bonds in a different molecule

false

a *blank* inhibitor binds to an area outside of the active site of an enzyme and impairs proper functioning of the enzyme

noncompetitive

hydrolysis of which covalent bonds in ATP releases a considerable amount of energy?

phosphate-phosphate bond

a fraction of the energy from the sun is captured by plants, algae, and some bacteria through the process of what?

photosynthesis

green plants, certain bacteria, and algae can all perform the process of *blank* during which the energy of light is used to synthesize molecules

photosynthesis

how can the functioning of an enzyme be affected by the external environment?

temperature and pH can greatly affect the function of some enzymes by causing denaturation

what is the first law of thermodynamics?

the energy cannot be created or destroyed

how does feedback regulation regulate enzyme activity?

the final product of a metabolic pathway inactivates the first enzyme in the pathway by binding to its allosteric site

select the statements that describe the free energy (G) change of a spontaneous reaction

the free energy of the products is less than the reactants; there is a negative free energy change

select the ways in which multienzyme complexes improve catalytic efficiency?

the product of one reaction can be delivered to the next enzyme more easily; because products don't leave the complex there are no unwanted side reactions; all of the reactions inside the complex can be controlled as one unit

select the true statements about endergonic reactions?

the products have a higher free energy than the reactants; endergonic reactions are not spontaneous; endergonic reactions have a positive change in free energy

which characteristic of ATP is responsible for its high energy?

the repulsion of the negative phosphate groups

the energy that flows through biological systems on earth ultimately comes from which source?

the sun

with very few exceptions, all energy that enters biological systems ultimately come from where?

the sun

is any energy released during ATP hydrolysis and is so, how much?

a considerable amount of energy is released

all cells use a molecule call *blank* to carry and release energy cynically

ATP

cells us *blank* hydrolysis to drive endergonic reactions

ATP

what molecule is a common energy source for living organisms?

ATP

in the following chemical reaction, which molecule(s) is(are) reduced? Ae- + B --> A + Be-

B

in a chemical reaction, an electron is transferred from molecule X to molecule Y. which of the two molecules is oxidized in this reaction?

X

cells harvest energy during *blank* reactions and expend energy during *blank* reactions

catabolic; anabolic

because cells are too small to maintain significant internal temperature differences, cells rely on *blank* reactions rather than a *blank* gradient to do work

chemical; heat

all activities of living organisms involve changes in *blank*, which is the ability to do work

energy

all living things require which of the following, in order to carry out chemical reactions and thereby survive?

energy

the first law of thermodynamics states that the total amount of *blank* in the universe remains constant

energy

what is stored in the chemical bonds of a molecule that can be used to make new bonds in a different molecule?

energy

which of the following is another way to state the second law of thermodynamics?

entropy increases

select the statements that correctly describe differences between anabolic and catabolic reactions

in catabolic reactions large molecules are broken down, while in anabolic reactions large molecules are made from smaller ones; catabolic reactions release energy while anabolic reaction need energy input

which of the following describes the major difference between kinetic and potential energy?

kinetic energy is the energy of motion and potential energy is associated with the position of an object

*blank* energy is associated with the movement, while *blank* energy is stored energy

kinetic; potential

when the free energy that occurs as a result of a chemical reaction is *blank* than zero, the reaction is spontaneous

less/lower

during a chemical reaction, which molecules become oxidized?

molecules that have an electron removed

during a chemical reaction which molecules become reduced?

molecules that have one or more electrons added

a more efficient way to catalyze a sequence of related biochemical reactions is to combine several proteins into a *blank* complex; in this way, the product of each reaction can be delivered to the next enzyme, without being released to diffuse away

multienzyme

what are enzymes?

proteins or RNA molecules that act as catalysts

order the steps in enzyme catalysis starting at the top

substrate binds to enzyme; amino acids from enzyme interact with substrate; bonds in substrate(s) are broken and/or created and products are formed; products dissociate from the enzyme

which of the following is the branch of chemistry concerned with energy changes?

thermodynamics

certain reactions in cells are endergonic. how do cells make those reactions proceed?

they couple them with ATP hydrolysis

which of the following statements about oxidized molecules is true?

they have fewer electrons and less energy than reduced molecules

select the true statement about enzymes

they lower the activation energy of a reaction by binding to the substrates

select the true statements about allosteric sites on enzymes

this is where a noncompetitive inhibitor would bind; the binding of a substance to the allosteric site can switch an enzyme between its active and inactive configurations

what is the second law of thermodynamics?

transformation of energy from one form to another increases entropy

true or false: chemical potential energy stored in the molecules of living organisms can be converted into other forms, such as kinetic energy, light , or electricity

true

true or false: heat energy cannot be used by cells to do work

true

true or false: the oxidized form of a molecule has less energy than its reduced form

true

true or false: thermodynamics is the study of energy changes in the universe

true

phosphate bonds in ATP are high energy bonds because they are . . .

unstable