What is metabolism?
The totality of an organism’s chemical reactions.
What gives rise to metabolism as an emergent property of life?
Orderly molecular interactions.
What defines a metabolic pathway?
A series of defined steps that alters a specific molecule to produce a product.
What catalyzes each step in a metabolic pathway?
A specific enzyme.
What do catabolic pathways do to complex molecules?
They break them into simpler compounds and release energy.
What is energy?
The ability to do work.
What are the two states in which energy exists?
Potential energy and kinetic energy.
Where is chemical energy stored?
In the structural arrangement of molecules.
What can happen to energy, though it cannot be created or destroyed?
It can be converted from one form to another.
What does entropy scientifically measure?
Molecular disorder or randomness.
What happens to universal entropy during every energy transfer or transformation, according to the Second Law?
It increases.
What characterizes a spontaneous process in terms of energy input and universal entropy?
It requires no energy input and increases universal entropy.
What does a nonspontaneous process require, and what happens to entropy?
It requires energy input and decreases entropy.
Why does local order in living systems not violate the Second Law?
Catabolic breakdown releases heat and small molecules into the environment.
What portion of a system’s energy is available to do work in a living cell at uniform temperature and pressure?
Free energy ().
How is the change in free energy calculated from final and initial free energy?
What does negative indicate about a reaction’s free energy change?
The reaction loses free energy.
What does negative indicate about a reaction’s stability and spontaneity?
The reaction becomes more stable and is spontaneous.
What is the stability and work capacity of a system at equilibrium?
It is maximally stable and can do no work.
How does an exergonic reaction affect free energy in its surroundings?
It releases free energy to its surroundings.
What three kinds of work do cells perform?
Chemical, transport, and mechanical work.
What does energy coupling use to drive an energy-consuming process?
An energy-releasing process.
What components make up ATP?
A sugar, an adenine nucleobase, and three phosphate groups.
What happens during ATP hydrolysis?
Water is added and the terminal phosphate bond is broken.
How is ATP regenerated from ADP?
A phosphate is added using energy from exergonic catabolic breakdown reactions.
What does ATP transfer to power an endergonic reaction?
Its terminal phosphate group.
What kind of molecule usually acts as an enzyme?
A macromolecule, almost always a protein.
What is activation energy?
The initial energy needed to break chemical bonds and start a reaction.
How do enzymes help reactions proceed rapidly at normal body temperature?
They selectively lower activation energy.
What can an enzyme change about a reaction?
Its speed, but not its or spontaneity.
What can increased temperature do to enzymes?
It can denature them.
What is a cofactor?
A non-protein helper required by many enzymes to function properly.
What causes feedback inhibition?
A reaction product acts as a repressor.
Where do noncompetitive inhibitors bind, and what effect follows?
They bind an allosteric site, changing the active-site shape so the substrate cannot bind.
What defines allosteric regulation?
A regulatory molecule binds at one protein site and affects function at another.
What does bioenergetics study?
How energy flows through living organisms.
What is the cellular respiration equation?
What equation represents photosynthesis?
What energy transformation is involved in work by living organisms?
Potential energy transforms into kinetic energy.
What movement is thermal energy associated with?
The random movement of atoms or molecules.
What is heat?
Thermal energy transferred from one object to another.
Why do complex organic molecules like glucose contain high chemical energy?
Significant energy is liberated as they break down into simpler products.
How do living organisms increase their surroundings’ disorder through metabolism?
They break down complex food molecules into heat and small molecules such as CO2.
What do living cells assemble from amino acids?
Ordered polypeptide chains.
How does energy enter and leave ecosystems?
It enters as light and exits permanently as heat.
How does high free energy compare with low free energy in stability and available energy?
High free energy indicates instability and more available energy; low free energy indicates greater stability and less available energy.
What do cells use reactions with negative to do?
Power cellular processes.
Why does ATP’s triphosphate tail store potential energy?
Its negatively charged phosphate groups repel one another.
What can ATP hydrolysis do to an energy-consuming reaction when coupled to it?
Make the coupled reaction net exergonic.
What does a catalyst do without being consumed or altered?
It drastically speeds up a chemical reaction.
How quickly can sucrase break down sucrose into glucose and fructose?
In seconds.
What happens at the transition state?
Reactants reach a highly unstable peak after absorbing enough energy to break their bonds.
Which suffix do most enzyme names have?
-ase.
What distinguishes coenzymes from inorganic cofactors?
Coenzymes are organic cofactors.
How do most vitamins support coenzyme production or function?
They function as coenzymes or supply materials to manufacture them.
How can poisons affect enzyme activity?
They can act as irreversible enzyme inhibitors.
Answer 27 questions on Metabolism and Bioenergetics.
1. What does metabolism encompass in a living organism?
2. A molecule is transformed through several defined steps, with a specific enzyme catalyzing each step; what is this sequence called?
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