Download Chapter 8 Notes – Energy and Metabolism

Chapter 8 Notes – Energy and Metabolism
Flow of Energy in Living Things
Energy - _______________________________
 kinetic - energy of motion
 potential - stored energy
Thermodynamics - _______________________________
 calorie - ___________________________________________________________
– kilocalorie = ____________ calories
Oxidation - Reduction
• Oxidation occurs when an atom or molecule _______________________.
– The loss of an electron means an _______________________
• Reduction occurs when an atom or molecule _______________________.
– The addition of an electron is a _______________________
• OILRIG: ______________________________________________
In redox reactions you must _______________________
 Redox reactions occur because ________________________________ by an atom
through oxidation is ____________________________________ through reduction.
 Oxidation and reduction always _______________________________
 The reduced form of a molecule has a _____________________ than the oxidized form
 The ability of organisms to store energy in molecules by transferring electrons to them is
referred to as ________________________, and is a fundamental property of living things
 The amount of energy an electron possess depends on ______________________
 Electrons close are held tightly and have _________________
 Electrons further away have ______________________
 What kind of processes can add energy to an electron to get it to move?
o ____________________________
 The added energy is stored as _____________________________ that the atom can later
release when the electron ____________________________________.
The First Law of Thermodynamics
– _____________________________________________________________________.
– During each conversion, ______________________________________________.
 Heat is defined as the measure of the _______________________________.
The Second Law of Thermodynamics
– The disorder _________________ in the universe is continuously __________________.
– Energy transformations proceed _____________________ to convert matter from a
__________________, less stable form, to a ________________, more stable form.
A clean room shows high ___________________________
A dirty room shows high _____________________________
Free Energy
Free energy refers to the amount of energy _______________________________________
____________________.
• Gibbs’ free energy (G)
– change in free energy
 endergonic - __________________________________________
 exergonic - ____________________________________________
Activation Energy
Activation energy refers to the ____________________________ to destabilize existing
chemical bonds and ______________________________________.
• catalyst - substance that ______________________________________
– cannot violate laws of thermodynamics.
 direction of a chemical reaction is determined solely by the difference in free
energy between the reactants and the products
Activation Energy and Catalysts
Enzymes Are Biological Catalysts
Enzymes are ________________ that ___________________________ in living organisms.
• Unique ____________________________ enables an enzyme to stabilize a _________
____________________ between substrates.
– Because the enzyme itself is _____________________________ in the reaction,
only a __________________________ is needed, and can then be reused.
Enzymes
Most enzymes are globular proteins with ________________________.
• Substrates ____________________________ at these active sites, forming an
_____________.___
Enzyme Forms
•
•
A ____________________ is composed of several enzymes, catalyzing the different steps
of a sequence of reactions, that are associated with one another.
–
subunits work in concert, providing significant advantages in catalytic efficiency
RNA catalysts _______________________
Factors Affecting Enzyme Activity
•
•
Temperature
–
Rate of an enzyme-catalyzed reaction _____________________, but only up to
_______________________________.
pH
–
Ionic interactions also hold enzymes together.
Inhibitors and activators
• inhibitor - substance that____________________________________________ its activity
• competitive inhibitors - compete with the _______________________________________
• noncompetitive inhibitors - bind to the enzyme in a _______________________________
– allosteric sites - specific binding sites acting as ___________________________
– activator - substances that
________________________ and keep
the enzymes in their __________________
__________________________________
– increase _____________________
– cofactors - chemical components that
____________________________
– coenzyme – when the cofactor is
________________________________
Enzyme Cofactors
coenzymes
• In many ox-red reactions catalyzed by enzymes, the electrons pass in pairs from the active
site of the enzyme to a coenzyme that serves as the electron acceptor
• The coenzyme transfers the electrons to a different enzyme which releases them
• Often the electrons combine with protons (H+)
• In this way, coenzymes shuttle energy in the form of hydrogen atoms
NAD+
• One of the most important coenzymes is the H acceptor __________________________
_____________________________________
• 2 nucleotides bound together
• NMP: nicotinamide monophosphate
• active _________________________________
• has site that is ___________________________
• AMP: adenine monophosphate
• acts as core __________________________
• When NAD+ acquires electrons and a H atom (or
two electrons and an H+ ion) it is __________
_____________________________________
• NADH now carries ________________________
__________________________which it can
supply to other molecules to reduce them.
•
•
Oxidation of energy containing molecules involves ____________________________
_________________________________________
Much of the energy donated to NADH is _______________________________________
Oxidation-reduction reactions often employ cofactors
Oxidation-reduction reactions often employ cofactors
ATP
•
__________________________ (ATP)
is the chief ______________________
of the cell.
• Each molecule is a nucleotide
composed of
___________________________
____
___________________________
___.
• energy stored in the
______________________
______
• cell uses ATP to drive
_________________
_______
Biochemical Pathways
•
Biochemical pathways are the _______________________________________.
– ______________ is the total of all chemical reactions carried out by an organism.
 anabolism - _____________________________
 catabolism - _____________________________
Video Biochemical Pathway
• Organisms contain many different kinds of enzymes
that ________________________________
__________________ ______________.
• Many of these reactions, such as those involved in
biosynthesis of an amino acid, are carried out in a
_________________________________ called a
biochemical pathway.
• In such pathways, a ______________________
_______________________ by the first enzyme in
the pathway and the product of the first reactions then
becomes the substrate for the next reaction.
• The_________________ of the first reaction then
becomes the _______________ for the second
enzyme.
• The sequence of reactions continues until the final
product is made.
• When a biolchemical pathway is functioning, the
____________________ is continually converted to
the final product through the ____________________
in the pathway.
What is happening to the molecule at
each step in the video?
Regulation of Biochemical Pathways
•
Biochemical pathways must be _____________________________ to operate efficiently.
– advantageous for cell to temporarily ____________________________ when their
products are not needed
 ________________________ - When the cell produces increasing quantities
of a particular product, it automatically inhibits its ability to produce more.
Video Feedback Inhibition
• Many of these reactions, such as those involved in biosynthesis of an amino acid, are carried out in
a specific sequence called a biochemical pathway.
• In such pathways, the product of the first reactions then becomes the substrate for the next
reaction.
• If the end product of a pathway, such as an amino acid, becomes available in the environment, it is
unnecessary and wasteful for the cells to continue to produce the product.
• Cells therefore have the ability to shut down a pathway when it is not needed. In feedback inhibition,
the end product of the pathway reacts with the first enzyme that is unique to the pathway.
• The reaction occurs at a site on the enzyme that is different from the active site, called the alosteric
site.
• When the product binds to the allosteric site, the enzyme undergoes a conformational change an
can no longer react with its substrate.
• There is no substrate for subsequent steps in the pathway and the final product is no longer
synthesized.
Terms that you should know from this chapter!!
activation energy
catalysis
coenzyme
endergonic reaction
entropy
exergonic reaction
free energy
metabolism
oxidation
reduction
substrate