bio ch 6

Which statement is true regarding catabolic pathways? a) Molecules are synthesized using dehydration synthesis. B) Polymers are broken down into their monomers. C) Catabolic pathways are used to construct macromolecules such as carbohydrates, lipids, and proteins. D) Catabolic reactions consume energy.

B) Polymers are broken down into their monomers.

As liquid water is heated on a hot plate. Which of the following changes would occur? a) The hot plate consumes energy as it transfers entropy. B) The entropy of the system will increase. C) The kinetic energy of the water molecules decreases. D) The water molecules become more closely packed when they are heated.

B) The entropy of the system will increase.

Which of the following is the best way to judge the relative activation energies between two given chemical reactions? a. Compare the ∆G values between the two reactions. b. Compare their reaction rates. c. Compare their ideal environmental conditions. d. Compare the spontaneity between the two reactions.

b. Compare their reaction rates.

Which of the following comparisons or contrasts between endergonic and exergonic reactions is false? a. Endergonic reactions have a positive ∆G and exergonic reactions have a negative ∆G. b. Endergonic reactions consume energy and exergonic reactions release energy. c. Both endergonic and exergonic reactions require a small amount of energy to overcome an activation barrier. d. Endergonic reactions take place slowly and exergonic reactions take place quickly.

b. Endergonic reactions consume energy and exergonic reactions release energy.

Energy is stored long-term in the bonds of _____ and used short-term to perform work from a(n) _____ molecule.

glucose : ATP

transition state

high-energy, unstable state (an intermediate form between the substrate and the product) occurring during a chemical reaction

Without the presence of enzymes, the reactions necessary to sustain life would require ___________________ in order to occur.

higher temperatures

Explain in your own words how enzyme feedback inhibition benefits a cell.

Feedback inhibition allows cells to control the amounts of metabolic products produced. If there is too much of a particular product relative to what the cell's needs, feedback inhibition effectively causes the cell to decrease production of that particular product.

free energy

Gibbs free energy is the usable energy, or energy that is available to do work

Describe the position of the transition state on a vertical energy scale, from low to high, relative to the position of the reactants and products, for both endergonic and exergonic reactions.

The transition state is always higher in energy than the reactants and the products of a reaction, doesn't matter if the reaction is endergonic or exergonic.

How do noncompetitive inhibitors interact with enzymes?

They bind to a location other than the active site, stopping the enzyme from functioning.

What is the primary function of cofactors?

To aid in enzyme function

feedback inhibition

a product's effect of a reaction sequence to decrease its further production by inhibiting the first enzyme's activity in the pathway that produces it

enthalpy

a system's total energy

Which of the following summarizes the first law of thermodynamics? a) Energy cannot be created or destroyed. B) Energy cannot be transferred or transformed. C) The total entropy of a system increases over time. D) Two systems that are in equilibrium with a third system are in equilibrium with one another.

a) Energy cannot be created or destroyed.

Enzyme names always end with the suffix

-ase

(fig 6.14) One ATP molecule's hydrolysis releases 7.3 kcal/mol of energy (∆G = −7.3 kcal/mol of energy). If it takes 2.1 kcal/mol of energy to move one Na+ across the membrane (∆G = +2.1 kcal/mol of energy), how many sodium ions could one ATP molecule's hydrolysis move?

3 Na+ ions can be moved by the hydrolysis of 1 ATP molecule. The ∆G of the coupled reaction must be negative. Movement of 3 Na+ ions across the membrane will take 6.3 kcal of energy (2.1 kcal × 3 Na+ ions = 6.3 kcal). Hydrolysis of ATP provides 7.3 kcal of energy. Movement of 4 Na+ ions across the membrane but would require 8.4 kcal of energy, more than 1 ATP molecule can provide.

(Figure 6.8) Look at each of the processes, and decide if it is endergonic or exergonic. In each case, does enthalpy increase or decrease, and does entropy increase or decrease?

A compost pile decomposing is an exergonic process; enthalpy increases and entropy increases. A baby developing from a fertilized egg is an endergonic process; enthalpy decreases and entropy decreases. Sand art being destroyed is an exergonic process; there is no change in enthalpy and entropy increases. A ball rolling downhill is an exergonic process; enthalpy decreases and there's no change in entropy.

Explain in your own words the difference between a spontaneous reaction and one that occurs instantaneously.

A spontaneous reaction has a negative ∆G and releases energy. But spontaneous reaction need not happen quickly like an instantaneous reaction. It may happen over long periods due to a large energy of activation, which prevents the reaction from occurring quickly.

kinetic energy

energy type that takes place with objects or particles in motion

What is the relationship between anabolic and catabolic pathways?

Anabolic pathways create complex molecules using the energy from catabolic pathways.

Which of the following are roles of amino acids at an enzyme's active site? a) Preventing the substrate from entering the chemical reaction B) Binding the substrate to the enzyme C) Converting the enzyme to receive a different substrate D) Changing the enzyme itself

B) Binding the substrate to the enzyme

Define anabolic and catabolic reactions. Describe each in terms of their change in free energy.

Catabolic: release energy by breaking down complex molecules into simpler compoundsAnabolic:consume energy to build complex molecules from simpler ones.In exergonic reaction its spontaneous so it doesn't require energy. It increase entropy, use hydrolysis and is catabolic.In endogenic reaction its non-spontaneous so it does require energy, decrease entropy, use dehydration and is anabolic.

Describe how enzymes are regulated by the cell.

Cells regulate the enzymes in metabolic pathways is through feedback inhibition. During feedback inhibition, metabolic pathway products serve as inhibitors of one or more of the enzymes involved in the pathway that produces them.

A scientist hydrolyzes ATP in a laboratory test tube. He finds that about 3 times as much heat is released than when the same amount of ATP is hydrolyzed in a cell. What best explains the scientist's observation? a) ATP hydrolysis in a cell makes different products than in a test tube. B) Enzymes in cells use heat energy to catalyze reactions. C) Cells are less efficient at producing heat. D) Cells often convert some of the energy from ATP hydrolysis into other usable forms.

D) Cells often convert some of the energy from ATP hydrolysis into other usable forms.

Which statement is true of enzymes? a)Changes in temperature do not affect enzymes. B) Enzymes work independent of substrate concentration. C) Enzymes are non-specific. D) The activity of an enzyme might change as pH changes.

D) The activity of an enzyme might change as pH changes.

What occurs when a phosphate-phosphate bond in an ATP molecule is broken?

Energy is released in a cell.

Name two different cellular functions that require energy that parallel human energy-requiring functions.

Energy is required for cellular motion, through beating of cilia or flagella, as well as human motion, produced by muscle contraction. Cells also need energy to perform digestion, as humans require energy to digest food.

With regard to enzymes, why are vitamins necessary for good health? Give examples

Enzymes are substances present in the living organism which acts as a catalyst to specific biochemical reactions. They help with digestion of nutrients in the body. Enzymes catalyze many important reactions, it is critical to obtain sufficient vitamins and minerals from diet and supplements. Vitamin C is a coenzyme necessary for the action of enzymes that build collagen.

activation site

enzyme's specific region to which the substrate binds

How is ATP hydrolysis used to power other cellular reactions?

It is coupled with endergonic reactions.

(fig 6.10) If no activation energy were required to break down sucrose (table sugar), would you be able to store it in a sugar bowl?

No. We can store chemical energy b/c of the need to overcome the barrier to its breakdown.

Pepstatin binds to the enzyme pepsin. The substrate is still able to bind to the active site, but the reaction is blocked. What is this an example of?

Noncompetitive Inhibition

Does physical exercise involve anabolic and/or catabolic processes? Give evidence for your answer.

Physical exercise involves both anabolic and catabolic processes. Body cells break down sugars to provide ATP to do the work necessary for exercise, such as muscle contractions. This is catabolism. Muscle cells also must repair muscle tissue damaged by exercise by building new muscle

Do you think that the EA for ATP hydrolysis is relatively low or high? Explain your reasoning.

The activation energy for hydrolysis is low. ATP hydrolysis an exergonic process with a large −∆G, but ATP is also a very unstable molecule that breaks down into ADP + Pi if not utilized fast enough. Meaning a very low E A since it hydrolyzes so quickly.

magine an elaborate ant farm with tunnels and passageways through the sand where ants live in a large community. Now imagine that an earthquake shook the ground and demolished the ant farm. In which of these two scenarios, before or after the earthquake, was the ant farm system in a state of higher or lower entropy?

The ant farm had lower entropy before the earthquake. After the earthquake, it had higher entropy.

Energy transfers take place constantly in everyday activities. Think of two scenarios: cooking on a stove and driving. Explain how the second law of thermodynamics applies to these two scenarios.

When cooking the food is heating up on the stovetop but not most of the heat goes to cooking the food, some is lost from heat energy to the air causing it to increase entropy. When driving the cars use gas to run the engine and move the car. Just like cooking the food some of the heat energy is lost which is why the hood and other parts of the car it heat up while the engine is turned on. This also increase entropy.

Which of the following forms of energy is correctly paired with its definition? a) Thermal energy - the energy in a system due to its temperature B) Potential energy - the energy associated with an object's motion C) Chemical energy - the energy contained within a system that is responsible for its temperature D) Kinetic energy - the stored energy of an object due to its position

a) Thermal energy - the energy in a system due to its temperature

Which of the following processes results in an increase of entropy? a) Water boiling B) Condensation of water vapor C) Water freezing into ice D) Crystallization of a salt from an aqueous solution

a) Water boiling

Which of the following is NOT true? a. Prokaryotic cells and viruses do not use enzymes b. Enzymes only work inside of cells c. Most enzymes are proteins d. Enzymes are used up after catalyzing a reaction

a. Prokaryotic cells and viruses do not use enzymes b. Enzymes only work inside of cells d. Enzymes are used up after catalyzing a reaction

Which of the following is not true about enzymes: a. They increase ∆G of reactions. b. They are usually made of amino acids. c. They lower the activation energy of chemical reactions. d. Each one is specific to the particular substrate(s) to which it binds.

a. They increase ∆G of reactions.

DNA replication involves unwinding two strands of parent DNA, copying each strand to synthesize complementary strands, and releasing the parent and daughter DNA. Which of the following accurately describes this process? a. This is an anabolic process. b. This is a catabolic process. c. This is both anabolic and catabolic. d. This is a metabolic process but is neither anabolic nor catabolic.

a. This is an anabolic process.

Which of the following analogies best describes the induced-fit model of enzyme-substrate binding? a. a hug between two people b. a key fitting into a lock c. a square peg fitting through the square hole and a round peg fitting through the round hole of a children's toy d. the fitting together of two jigsaw puzzle pieces

a. a hug between two people

In a reaction between the sugar maltose, and the enzyme maltase, which catalyzes the decomposition of maltose a. maltose is the substrate b. maltase is the substrate c. maltose is the product d. maltase is the product e. water is the substrate

a. maltose is the substrate

Which of the following molecules is likely to have the most potential energy? a. sucrose b. ATP c. glucose d. ADP

a. sucrose

Which of the following is not an example of an energy transformation? a. turning on a light switch b. solar panels at work c. formation of static electricity d. none of the above

a. turning on a light switch

ATP

adenosine triphosphate, the cell's energy currency

metabolism

all the chemical reactions that take place inside cells, including anabolism and catabolism

A+B+energy-> energy Which of the following best describes the above reaction?

anabolic reaction

In each of the three systems, determine the state of entropy (low or high) when comparing the first and second: i. the instant that a perfume bottle is sprayed compared with 30 seconds later, ii. an old 1950s car compared with a brand new car, and iii. a living cell compared with a dead cell. a. i. low, ii. high, iii. low b. i. low, ii. high, iii. high c. i. high, ii. low, iii. high d. i. high, ii. low, iii. low

b. i. low, ii. high, iii. high

Phosphoanhydride bond

bond that connects phosphates in an ATP molecule

An allosteric inhibitor does which of the following? a. Binds to an enzyme away from the active site and changes the conformation of the active site, increasing its affinity for substrate binding. b. Binds to the active site and blocks it from binding substrate. c. Binds to an enzyme away from the active site and changes the conformation of the active site, decreasing its affinity for the substrate. d. Binds directly to the active site and mimics the substrate.

c. Binds to an enzyme away from the active site and changes the conformation of the active site, decreasing its affinity for the substrate.

Disulfiram binds to the active site of the enzyme aldehyde oxidase, blocking the binding of its substrate. What kind of a molecule is disulfiram?

competitive inhibition

Exergonic

describes chemical reactions that release free energy

endergonic

describes chemical reactions that require energy input

induced fit

dynamic fit between the enzyme and its substrate, in which both components modify their structures to allow for ideal binding

activation energy

energy necessary for reactions to occur

heat

energy transferred from one system to another that is not work (energy of the molecules' motion or particles)

potential energy

energy type that has the potential to do work; stored energy

Consider a pendulum swinging. Which type(s) of energy is/are associated with the pendulum in the following instances: i. the moment at which it completes one cycle, just before it begins to fall back towards the other end, ii. the moment that it is in the middle between the two ends, and iii. just before it reaches the end of one cycle (just before instant i.).

i. potential, ii. kinetic, iii. potential and kinetic

allosteric inhibition

inhibition by a binding event at a site different from the active site, which induces a conformational change and reduces the enzyme's affinity for its substrate

cofactor

inorganic ion, such as iron and magnesium ions, required for optimal enzyme activity regulation

Enzymes speed up a reaction by

lowering the activation energy

entropy (S)

measure of randomness or disorder within a system

substrate

molecule on which the enzyme acts

Cells must produce many different enzymes because

most cellular reactions require a specific, unique enzyme

Catabolic (catabolism)

pathways in which complex molecules break down into simpler ones

anabolic (anabolism)

pathways that require an energy input to synthesize complex molecules from simpler ones

When a piece of liver is dropped into hydrogen peroxide, the peroxide bubbles vigorously as a result of what reaction?

peroxide being broken into water and oxygen

chemical energy

potential energy in chemical bonds that releases when those bonds are broken

energy coupling

process during which energy released by one reaction is used to drive another reaction

denature

process that changes a substance's natural properties

Enzymes are composed of what organic molecule?

proteins

The energy released by the hydrolysis of ATP is____

providing energy to coupled reactions

coenzyme

small organic molecule, such as a vitamin or its derivative, which is required to enhance an enzyme's activity

Thermodynamics

study of energy and energy transfer involving physical matter

Bioenergetics

study of energy flowing through living systems

When a piece of liver is dropped into hydrogen peroxide, the peroxide bubbles vigorously as the hydrogen peroxide (H2O2) decomposes into water (H2O) and oxygen (O2). This rapid change in reaction rate suggests

the liver contains an enzyme that breaks down hydrogen peroxide

heat energy

total bond energy of reactants or products in a chemical reaction

competeive inhibition

type of inhibition in which the inhibitor competes with the substrate molecule by binding to the enzyme's active site