Chapter 6

Select all of the following that exhibit potential energy only.

A boulder sitting at the top of a hill Water at the top of a dam A stretched rubber band Bow ready to fire an arrow

What is entropy?

A measure of the amount of disorder in a system

All cells use a molecule called ____ to carry and release energy cyclically.

ATP

The interaction between enzyme and substrate resembles a lock and key. Which of the following accurately describes this analogy?

An enzyme is like a lock, into which the substrate must fit like a key.

Which of the following are examples of catabolic reactions?

Breakdown of glucose into 2 pyruvate molecules Breakdown of RNA by nucleases Breakdown of proteins by proteases

Which of the following are ways that enzymes act to increase the rate of a chemical reaction?

Changing the local environment of the reactants Positioning the reactants very close to each other Lowering the activation energy Straining the bonds in the reactants

Select all of the cellular processes that require a net input of energy.

Endergonic reactions Cellular movements ATP synthesis

Select the true statements about endergonic reactions.

Endergonic reactions have a positive change in free energy. The products have a higher free energy than the reactants. Endergonic reactions are not spontaneous. Endergonic reactions require the addition of free energy.

Select the reasons why changes in the pH of the fluid in which an enzyme is dissolved affect the enzyme's ability to function.

Enzymes have particular pH values at which they function best.

How does the change in free energy differ between exergonic and endergonic reactions?

Exergonic reactions have a negative change in free energy whereas endergonic reactions have a positive change in free energy.

What are some examples of cellular processes that require energy?

Muscle contraction, cellular movements, chemical reactions

Select all of the following that can occur during the reduction of an atom or molecule.

One or more electrons are added to the atom or molecule. The net charge of the atom or molecule decreases due to addition of negatively charged electron(s).

Select all of the following that are true statements about proteasomes.

Proteasomes contain enzymes (called proteases )that degrade unwanted proteins within the cell. Proteasomes are protein complexes involved in the primary biological pathway that degrades proteins in archaea and eukaryotic cells.

Which of the following are examples of macromolecules that are synthesized by the cell?

RNA Proteins

Select all of the differences between reduction and oxidation.

Reduction is the addition of electrons and oxidation is the removal of electrons. Reduction will decrease the net charge of a molecule while oxidation will increase the net charge.

During which step does organelle degradation and recycling take place during the process of autophagy?

The autophagosome fuses with a lysosome.

The hydrolysis of ATP can be used to drive a chemical reaction that cannot occur spontaneously because:

The hydrolysis of ATP is exergonic. The hydrolysis of ATP has a negative ΔG.

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

There is a negative free energy change. Free energy is released during product formation. The free energy of the products is less than the reactants.

What factors determine the direction and rate of a chemical reaction?

Thermodynamics governs the direction of a reaction but not the rate of a reaction. The change in free energy will determine the direction of the reaction. Catalysts influence the rate of a chemical reaction.

What are the two general functions of catabolic pathways?

To recycle the components of organic molecules for use in the synthesis of new molecules To obtain energy for use in endergonic processes

True or false: Polymers of ubiquitin proteins must be attached to a protein that is targeted for degradation before it is directed to the proteasome.

True

Why is some energy unusable by living organisms?

When energy transformations occur, the entropy of the system increases, which cannot be harnessed in a useful way.

Enzyme-mediated chemical reactions take place when the substrate molecules bind to the _____ ______ of an enzyme

active site

Where does a substrate bind on an enzyme in order for a chemical reaction to take place?

active site

The digestion of intracellular material, such as worn-out organelles, occurs by a process called

autophagy

The breakdown of RNA molecules by nucleases into nucleotides is an example of what type of reaction?

catabolic

What do organic molecules provide?

chemical bonds to store energy building blocks

The first law of thermodynamics is also known as the law of _____ of energy

conservation

Some energy is unusable by living organisms. This is because energy transformations result in an increase in:

disorder heat entropy

The laws of thermodynamics state that ____ cannot be created or destroyed and that the _____ of a system tends to increase.

energy, entropy

Chemical ____ occurs when the rate of formation of products equals the rate of formation of reactants.

equilibrium

What type of reaction results in products that contain less free energy than the reactants do?

exergonic reaction exergonic spontaneous reaction spontaneous

What is the term used to describe the energy of a system that is available to do work?

free energy

What is the term used to describe the usable energy of a system?

free energy

Altering the pH outside the optimal range for a protein can cause denaturation and can ______ the function of an enzyme.

impair

When a physical system becomes more disordered, the entropy

increase

When the free energy change that occurs as a result of a chemical reaction is _____ than zero, the reaction is spontaneous.

less

During the process of autophagy, different types of acid hydrolases found in the ______ break down complex cellular materials such as worn-out organelles.

lysosomes

ATP hydrolysis can be used to drive chemical reactions because the hydrolysis of ATP has a ΔG that is:

negative

Exergonic reactions have a(n) ____change in free energy, and endergonic reactions have a(n)_____ change in free energy

negative, positive

Direction and _______ are the two main factors that determine the fate of a chemical reaction.

rate, speed or velocity

According to the ____ law of thermodynamics, entropy increases when energy is transferred from one form to another and some is lost as heat in the process.

second

Consider the reversible reaction: A + B ↔ C + D. Whether C + D are favored over A + B will depend upon:

the concentrations of reactants and products the energy input required

Select all of the following that describe metabolic pathways.

the product of one reaction becomes the substrate for the next reaction can result in the synthesis of larger molecules from smaller molecules can result in the breakdown of large molecules a different enzyme catalyzes each step