Chapter 8 - Introduction to Metabolism Flashcards
What is the first law of thermodynamics?
Energy can be transferred and transformed, but it cannot be created or destroyed.
What is the Second Law of Thermodynamics?
Every energy transfer or transformation increases the entropy (disorder) of the universe
What is an emergent property of life which arises from orderly interactions between molecules?
Metabolism
Metabolism
The totality of all chemical reactions in an organism.
When a molecule is altered in a series of defined steps which results in a specific product. It is referred to as a ________________ .
Metabolic Pathway
In a metabolic pathway. Each step is _________ by a specific ____________ .
catalyzed; enzyme
A ____________ that speeds up a specific reaction is an __________ .
macromolecule; enzyme
A process which breaks down complex molecules to simpler compounds is a ___________________ .
catabolic pathway
___________ consume energy to build complex molecules from simple molecules.
Anabolic Pathways
In _________ energy is stored by building bonds between atoms.
dehydration synthesis
In ____________ , bonds between atoms are broken to release energy.
Hydrolysis
When you ________ a reaction, you increase the speed of the reaction.
Catalyze
________ is the capacity to cause change.
Energy
________ is _______ associated with the relative motion of objects.
Kinetic energy
_______ is ________ associated with the random movement of atoms or molecules.
Thermal energy
The study of energy transformations which occur in a collection of matter is called ____________
Thermodynamics
______ is in transfer from one object to another is called _______.
Thermal Energy; Heat
_________ is the _______ available for release in a chemical reaction.
Chemical energy; potential energy
_______ is a measure of molecular disorder or randomness.
Entropy
__________ prevents the transfer of energy.
Insulation
In an ___________ , energy and matter can be transferred between a system and its surroundings.
open system
An organism is an ________ system
Open
In a _________ , a process can proceed without requiring an input of energy.
spontaneous process
A __________ requires an input of energy to proceed.
nonspontaneous process
_________ is the portion of a system’s energy that can perform work when temperature and pressure are uniform.
Free Energy
Equation for the change in free energy.
(Delta)G = (Delta)H - T(Delta)S
A spontaneous process will have a ________ (Delta)G
negative
A nonspontaneous process will have a ________ (delta)G
positive
An _________ reaction proceeds with a net release of free energy.
exergonic
A __________ requires an input of energy to proceed.
Endergonic
An exergonic reaction is a _________ reaction
downhill
An endergonic reaction is __________.
uphill
In ________ cells use an exergonic process to drive an endergonic one.
energy coupling
__________ is the transfer of a phosphate group from ATP to another molecule
phosphorylation
(delta)H is
change in enthalpy (or total energy)
(Delta)S
Change in entropy
If (delta)G is negative, a system uses _______ and becomes more _______.
free energy; stable
The point at which forward and reverse actions occur at the same rate.
Equilibrium
A ________ is a macromolecule that acts a catalyst.
Enzyme
A _____ is a chemical agent that speeds up a reaction without being consumed by a reaction.
Catalyst
__________ is the initial investment of energy required to start a reaction.
activation energy
_______ speed up chemical reactions by lowering __________
Enzymes; energy barriers.
___________ catalyzes the breakdown of ________ to glucose and fructoes
sucrase; sucrose
Every chemical reaction between molecules involves ___________ and __________.
Bond breaking; bond forming
_______ is the initial amount of energy required to break the bonds in reactants.
Activation Energy E(sub)A
When enough energy is absorbed to break bonds; molecules become unstable. This is the _________.
Transition State
_______ in the form of ________ often supplies activation energy.
Thermal energy; heat
As atoms settle into new, more stable bonds, energy is ____________
released to the surroundings.
In an exercongic reaction, ________ energy is released into the surroundings than was invested in breaking the old bonds.
more
Catalysis
The process by which a catalyst selectively speeds up a reaction without itself being consumed
An enzyme catalyzes a reaction by lowering the ___________ enough for the reaction to occur at moderate temperatures.
Activation Energy barrier
Can an enzyme change the amount of free energy in a system?
No. It only speeds up a reaction that would eventually occur anyway.
substrate
The reactant that an enzyme acts on.
If an enzyme binds to a substrate. It forms an ________
Enzyme substrate complex.
The _____ is the region on the enzyme, often a pocket or groove, that binds to the substrate
active site
Interactions between chemical groups on the substrate and the active site create an
induced fit
The substrate is typically held in the enzyme’s active site by ________.
weak bonds
How do you speed up the rate of an enzyme-catalyzed reaction?
Increase the concentration of substrate
When all enzyme molecules have their active sites engaged, the enzyme is ______________.
saturated
If the enzyme is saturated, the reaction rate can only be sped up by:
adding more enzyme
Enzyme activity can be affected by environmental factors, such as ___________ and __________.
temperature: pH
If you go over the optimal temperature of an enzyme, the reaction rate will _______
decrease
An enzyme that works in the stomach would work at a pH of about
2
An enzyme that works in the intestine would work at a pH of about
8
Nonprotein helpers that bind to the enzyme permanently, or reversibly with the substrate
Cofactors
Inorganic cofactors
iron; copper zinc (all ions)
Organic cofactors are called
coenzymes
What is an example of an organic coenzyme?
A vitamin
Enzymes are selectively inhibited by:
Enzyme inhibitors
Are the actions of an enzyme inhibitor permanent?
If the inhibitor bonds to an enzyme using a covalent bond, the inhibition is usually irreversible. Many inhibitors however bond using weak bonds. In this case the inhibition can be temporary.
A ___________ closely resembles a substrate and can bind to an enzymes active site.
competitive inhibitor
How would you overcome an enzyme inhibitor?
Increase the amount of substrate.
What inhibitor binds to an enzyme away from the active site?
A noncompetitive inhibitor. It changes the shape of the enzyme. This makes the active site less effective at catalyzing the reaction.
What are examples of enzyme inhibitors?
Toxins; pesticides, sarin gas
Why are enzymes important in metabolism?
Enzyme activity allows metabolic pathways to work.
How to cells regulate metabolism?
By switching on or off the genes that code for specific enzymes. Another way is to regulate the activity of specific enzymes.
In ______________________ the end product of a pathway shuts down that pathway.
feedback regulation
What prevents a cell from wasting resources by producing more product than is needed?
Feedback inhibition.
When a regulatory molecule binds to a protein at one site and affects the protein’s function at another site
Allosteric regulation
What is the effect of Allosteric Regulation?
To inhibit or stimulate enzyme activity.
In ___________, substrate binding to one active site triggers a shape change in the enzyme that stabilizes the active form for all other sites
cooperativity
