BIO CH 6

ATP is used in the cell to transfer energy. Indicate if the following statements about ATP are true or false. 1. When ATP is used in a reaction, the last phosphate is transferred to the substrate. 2. The release of the last phosphate from ATP is endergonic. 3. Once phosphates are released from ATP they can be added back in an endergonic reaction. 4. Creatine-P to creatine has a ΔG of -11kcal/mole and thus can be used to generate ATP from ADP. 5. When ATP is hydrolyzed to form ADP, the energy is released into the cytoplasm where enzymes use it to run endergonic reactions.

1. True 2. False 3. True 4. True 5. False

Consider the biochemical pathway below, where A, B, and C are substrates and products and E1 and E2 are the enzymes that catalyze the reactions. If Enzyme 1 (E1) is inactive, which of the following compounds will accumulate? A--E1--> B --E2--> C B only A only C only A and B B and C

A only

Indicate the examples below that illustrate the first law of thermodynamics. A plant uses sunlight to form a H+ gradient A H+ gradient is used to produce ATP 10% of the energy in one trophic level can be passed to the next trophic level An animal uses ATP to move its muscles An animal produces heat in the process of metabolism.

A plant uses sunlight to form a H+ gradient A H+ gradient is used to produce ATP An animal uses ATP to move its muscles

A bowl of sugar water is very stable. However, cells can rapidly break down sugar into carbon dioxide and water. What is the best explanation for this observation? -Breakdown of glucose has a negative delta G outside of cells, but a positive delta G inside cells -Glucose becomes more chemically reactive inside a cell -Enzymes in the cell catalyze the breakdown of glucose -The water is activated by the presence of living cells -Cells use energy to break down glucose -Living cells make the water warmer, speeding up the reaction

Enzymes in the cell catalyze the breakdown of glucose

Inhibiting one step in a biochemical pathway will not have any affect on the rates of the other reactions in the pathway. True or False

False

Noncompetitive inhibitors bind the active site of an enzyme, reducing its activity and the subsequent formation of product. True or False

False

What would your predict about the following reaction? Pi + ADP → ATP It has a change in free energy that is greater than 0 It yields energy It has a change in free energy that is greater than 0, and hence can be used to drive endergonic reactions It has a change in free energy that is less than 0 It can be used to drive endergonic reactions

It has a change in free energy that is greater than 0

Based on the reaction in the animation, what can you say about the change in free energy of the cleavage of sucrose into glucose and fructose? It is positive and the reaction is exergonic It is negative and the reaction is endergonic It is positive and the reaction is endergonic It is negative and the reaction is exergonic

It is negative and the reaction is exergonic

What happens to sucrase when it binds to sucrose? -Sucrase goes through a conformational (shape) change -Sucrase is cleaved in half -Sucrase becomes denatured -Sucrase releases energy to the sucrose

Sucrase goes through a conformational (shape) change

A mutation occurred in the gene that encodes the enzyme sucrase, resulting in a single amino acid substitution in the active site of the enzyme; a polar amino acid changed to a nonpolar amino acid. What is probably the result of this mutation. -Sucrase will not be able to bind sucrose in the active site -Sucrase will no longer be specific to sucrose. It will now hydrolyze a variety of disaccharides. -Sucrase will bind sucrose, but will not catalyze the hydrolysis reaction. -A single amino acid substitution will probably not affect the enzyme.

Sucrase will not be able to bind sucrose in the active site

What would you predict about a reaction that has a ΔG < 0? The reaction will require energy and is spontaneous The reaction will yield energy The reaction will require energy The reaction will yield energy and is spontaneous The reaction is spontaneous

The reaction will yield energy and is spontaneous

A reaction with a ΔG > 0 is endergonic and requires a net input of energy to proceed. True or False

True

In a biochemical pathway, the product released by the first enzyme becomes the substrate for the second enzyme. Group starts True or False

True

Temperature, pH, and ionic concentrations each play an important role in the proper functioning of enzymes. True or False

True

Energetic molecules such as NADH and ATP are often reactants of _____ reactions.

anabolic

In photosynthesis, carbon dioxide gas is reduced and combined to form glucose. This is an example of exergonic catabolism anabolism hydrolysis metabolism

anabolism

Energetic molecules such as NADH and ATP are often products of _____ reactions.

catabolic

The process of breaking glycogen down to glucose is an example of catabolism dehydration metabolism anabolism catalysis

catabolism

You measure the amount of enzyme activity in the presence of compound X and note that as you add more substrate the amount of enzyme activity increases. This indicates that the compound X is an allosteric inhibitor activator competitive inhibitor enzyme non-competitive inhibitor

competitive inhibitor

An autotroph captures energy from other sources and does not actually produce energy because kinetic energy is based on location the transfer of energy increases entropy the transfer of energy increases the disorder of a system energy cannot be created or destroyed once energy is created it can be destroyed

energy cannot be created or destroyed

How often can a sucrase molecule be used to hydrolyze sucrose? -once -twice -many times -never

many

In the reaction A− +B →A + B−, molecules A and B are both reduced molecules A and B are both oxidized molecule A is oxidized and molecule B is unchanged molecule A is oxidized and molecule B is reduced molecule A is reduced and molecule B is oxidized

molecule A is oxidized and molecule B is reduced

All of the following are a form of potential energy that can be used by a cell EXCEPT ATP NADH concentration gradient an electrical/ion gradient nitrogen

nitrogen

Consider the biochemical pathway below, where A, B, and C are substrates and products and E1 and E2 are the enzymes that catalyze the reactions. Enzyme 1 (E1) can utilize A --E1--> B --E2--> C either A or B as substrate, but not both neither A nor B as substrate only A as substrate both A and B as substrates only B as substrate

only A as substrate

Altering the three-dimensional structure of an enzyme might prevent the substrate from binding the enzyme's active site prevent the enzyme from adding energy to a reaction change the amount of energy needed for a reaction change the type of product produced in the reaction change the type of substrate that binds the enzyme's active site

prevent the substrate from binding the enzyme's active site

The primary function of an enzyme or any biological catalyst is to -change the direction of a reaction -increase the rate of a reaction and change the direction of a reaction -increase the rate of a reaction -reduce the energy of activation and increase the rate of a reaction -reduce the energy of activation of a reaction

reduce the energy of activation and increase the rate of a reaction

In the reaction Pyruvate + NADH -> Lactate + NAD+, pyruvate is being __________, while NADH is being _________.

reduce, oxidized

In ALL exergonic reactions, -the reactions are nonspontaneous -the reaction proceeds with a net release of free energy -a net input of energy from the surroundings is required for the reactions to proceed -the products have more total energy than the reactants -some reactants will be converted to products

the reaction proceeds with a net release of free energy