Biology Chapter 8: An Introduction to Metabolism
The optimal pH values for most enzymes fall in the range of ___________.
6-8
An organism at work uses __________ continuously.
ATP
__________ is responsible for mediating most energy coupling in cells.
ATP
____________ is a renewable resource that can be regenerated by dephosphorylation.
ATP
What is the shuttling of inorganic phosphate and energy called?
ATP cycle
What is the portion of a system's energy that can perform work when temperature and pressure are uniform throughout the system?
Gibbs free energy (G)
What is the symbol for entropy?
S
___________________ is the energy required to break bonds between reactant molecules.
activation energy
The binding of a(n) ________________ to a regulatory site stabilizes the shape that has functional active sites, while the binding of a(n) ____________________ stabilizes the inactive form of the enzyme.
activator, inhibitor
The restricted region of the enzyme molecule that binds to the substrate is called the _______________.
active site
When an enzyme population is saturated, what is the only way to increase the rate of product formation?
add more enzyme
____________ is the term used to describe any case in which a protein's function at one site is affected by the binding of a regulatory molecule to a separate site, resulting in either inhibition or stimulation of an enzyme's activity.
allosteric regulation
If a given process leads to an increase in entropy, it can proceed without requiring _______________.
an input of energy
What is a process that consumes energy to build complicated molecules from simpler ones?
anabolic (biosynthetic) pathway
The fact that metabolism as a whole is never _______________ is one of the defining features of life.
at equilibrium
What is mechanical work in a cell?
beating of cilia, contraction of muscle cells, movement of chromosomes, etc.
During every energy transfer or transformation, some energy becomes unavailable to do work due to __________________.
being released to the surroundings as heat
What is the study of how energy flows through living organisms?
bioenergetics
What is a degradative process that breaks down complex molecules to simpler compounds?
catabolic pathway
Organisms use the process of _________________ to speed up reactions.
catalysis
Most allosterically regulated enzymes oscillate between two different shapes: ___________________ and ___________________.
catalytically active, catalytically inactive
What is a major pathway of catabolism?
cellular respiration
What is the potential energy available for release in a chemical reaction?
chemical energy
What 3 main kinds of work does a cell do?
chemical, transport, mechanical
Certain ______________ selectively inhibit the actions of specific enzymes.
chemicals
If the cofactor is an organic molecule, it is called a(n) ____________.
coenzyme
Nonprotein helpers for catalytic activity are called ____________.
cofactors
______________ inhibition can be overcome by increasing the concentration of substrate so that as active sites become available, more substrate molecules than inhibitor molecules are able to gain entry to the sites.
competitive
___________________ compete with the substrate for admission into the active site and reduce the productivity of enzymes.
competitive inhibitors
Anabolic pathways _______________ energy and are considered "________________" reactions.
consume, uphill
______________ is a type of allosteric regulation in which a substrate molecule binds to one active site in a multisubunit enzyme, triggering a shape change in all units.
cooperativity
A cell at metabolic equilibrium is _____________.
dead
Delta G =
delta H - T x delta S
Is the regeneration of ATP exergonic or endergonic?
endergonic
What is the ability to rearrange a collection of matter?
energy
What is the capacity to cause change?
energy
The use of an exergonic process to drive an endergonic one is called ____________.
energy coupling
____________ is a measure of disorder or randomness.
entropy
A(n) ________________ is a macromolecule that acts as a catalyst to speed up a reaction.
enzyme
Each step of a metabolic pathway is catalyzed by a specific ____________.
enzyme
The enzyme binds to the substrate and forms a(n) ________________.
enzyme-substrate complex
A state of maximum stability is __________.
equilibrium
The net effect of a metabolic reaction is always in the direction of ______________.
equilibrium
The ATP cycle couples the cell's ____________ processes with its _____________ processes.
exergonic, endergonic
The more concentrated the substrate is, the ______________ the substrate will be converted to product by the enzyme.
faster
In ___________________, a metabolic pathway is halted by the inhibitory binding of its end product to an enzyme that acts early in the pathway.
feedback inhibition
The _______________ Law of Thermodynamics states that the energy of the universe is constant.
first
The key to coupling exergonic and endergonic reactions is the __________.
formation of the phosphorylated intermediate
In cellular respiration, _____________ is broken down into ________________.
glucose; carbon dioxide and water
Thermal energy in transfer from one object to another is called ___________.
heat
Unstable systems have ____________ G and are more likely to change to become more stable (______________ G).
higher, lower
Although order can _______________ locally, there is an unstoppable trend toward randomization of the universe as a whole.
increase
Up to a certain point, the rate of an enzymatic reaction _______________ with increasing temperature.
increases
When the binding between an enzyme and substrate becomes tighter after the initial contact, it is called _____________.
induced fit
Free energy is the measure of a system's ____________.
instability
A(n) _______________ system is unable to exchange either energy or matter with its surroundings outside.
isolated
Organisms are islands of _____________ entropy in an increasingly random universe.
low
How does an enzyme catalyze a reaction?
lowers activation energy
A(n) ____________________ begins with a specific molecule, which is then altered in a series of defined steps, resulting in a certain product.
metabolic pathway
The totality of an organism's chemical reactions is called _____________.
metabolism
What manages the material and energy resources of a cell?
metabolism
Delta G is ____________ for an exergonic reaction.
negative
Only processes with a _______________ delta G are spontaneous.
negative
____________________ do not directly compete with the substrate to bind to the enzyme at the active site; they instead impede enzyme reactions by binding to another part of the enzyme, causing it to change its shape so that the enzyme becomes less effective at converting the substrate to product.
noncompetitive inhibitors
A process that leads to a decrease in entropy is said to be _____________.
nonspontaneous
The formation of ATP from ADP and P is _____________.
nonspontaneous
A(n) _________________ system allows energy and matter to be transferred between the system and its surroundings.
open
What type of systems are organisms?
open systems
Cells create _______________ from less ordered starting materials.
ordered structures
The molecule that receives a phosphate group in phosphorylation is called a(n) ________________.
phosphorylated intermediate
Delta G is ________________ for an endergonic reaction.
positive
In a cell, the ______________ from one enzyme becomes the ____________ of another until the end product is released.
product, substrate
Most enzymes are ______________.
proteins
Catabolic pathways ____________ energy and are considered "_____________" reactions.
release, downhill
The breaking of bonds ___________ energy; it does not release energy.
requires
An enzyme is said to be ________________ when all enzyme molecules have their active sites engaged with substrates.
saturated
The __________________ Law of Thermodynamics states that every energy transfer or transformation increases the entropy of the universe.
second
The specificity of an enzyme results from its _____________.
shape
Phosphorylation and dephosphorylation promote crucial protein ______________.
shape changes
ATP hydrolysis leads to a change in a protein's __________ and its __________________________.
shape, ability to bind to another molecule
A process that does not require an input of energy is said to be _______________.
spontaneous
The reactant an enzyme acts on is called the ______________.
substrate
What is transport work in a cell?
the pumping of substances across membranes against the direction of spontaneous movement
What is chemical work in a cell?
the pushing of endergonic reactions that would not occur spontaneously
What is enthalpy in biology?
the total energy of a system
What is phosphorylation?
the transfer of a phosphate group from ATP to some other molecule, such as the reactant
_____________ is kinetic energy associated with the random movement of atoms or molecules.
thermal energy
What is the study of the energy transformations that occur in a collection of matter?
thermodynamics
The work of life depends on a cell's ability to ________________.
transform energy from one form to another
When molecules have absorbed enough energy for their bonds to break, they are in an unstable state called the _______________.
transition state
Substrates are held in the active site by __________________.
weak interactions (hydrogen bonds, ionic bonds, etc.)
Are enzymes specific to the molecule they catalyze?
yes
Are exergonic reactions spontaneous?
yes
If a process is spontaneous, is it energetically favorable?
yes
