Chapter 8: An Introduction to Metabolism Flashcards
What is metabolism?
the totality of an organisms chemical reactions
What are the two different types of pathways for metabolic processes?
catabolic and anabolic pathways
What are metabolic pathways?
begins with a specific molecule which is then altered into a certain product through a series of defined steps
What is each step of a metabolic pathway catalyzed by?
A specific enzyme
What is a catabolic pathway?
break down pathways
What is a anabolic pathway?
biosynthetic pathways
The process of turning complex molecules into simple compounds is known as what?
catabolic pathways
What is the opposite of a catabolic pathway?
Anabolic pathway
What are bioenergetics?
the study of how energy flows through living organisms
What is energy defined as?
the capacity to cause change
What is kinetic energy?
the energy associated with relative motion of objects
What is thermal energy?
kinetic energy associated with the random movement of atoms/molecuels
What is heat defined as?
thermal energy IN TRANSFERfrom one object to another
What is potential energy?
Energy that is not kinetic. Is due to its specific location/structure
What is chemical energy?
the potential energy available for release in a chemical reaction
Glucose is high in ______ energy
chemical
what are thermodynamics?
the study of energy transformations that occur in a collection of matter
How are collection of matter denoted?
systems and their surrounding
What is an isolated system
unable to exchange either energy or matter with its surroundings
What is an open system?
Can exchange energy/matter w/ surroundings
Are organisms open or closed systems?
open
What is the first law of thermodynamics?
conservation of energy
What is the second law of thermodynamics?
Every energy transfer/transformation increases the disorder (entropy) of the universe
What is entropy?
a measure of molecular disorder/randomness
What is spontaneous process?
A process that is energetically favorable?
Living systems ______ the entropy of their surroundings
increase
(Cells/Organisms) create ordered structures from less organized molecules
Cells
Depletion of chemical energy will lead to what?
Will increase heat
What is free energy?
the portion of a systems energy that can perform work
What is critical for free energy?
temperature and pressure must be uniform through out
What is the equation for free energy (G)?
change in G= change in H (enthalpy) - T(change in entropy)
Enthalpy in biological systems is equivalent to what?
total energy
Every spontaneous process ______ the systems free energy
decreases
What is an exergonic reaction?
(Energy outward) A net release of free energy.
What is an endergonic reaction?
a reaction that absorbs energy from its surroundings
What kind of reaction stores free energy in molecules?
endergonic reactions
When change in energy is negative a ______ reaction is occurring
exergonic
What are the three different kinds of work a cell does?
- chemical
- transport
- mechanical
What is chemical work?
the pushing of endergonic reactions that would not occur spontaneously
What is transport work?
the pumping of substances across membranes against direction of spontaneous movement
what is mechanical work?
such as the beating of cilia, muscle contractions, ect.
What is energy coupling?
the use of exergonic process to drive endergonic process
What are the components of ATP?
Adenine
Ribose
Triphosphate Group
As ATP loses phosphate groups what happens to free energy?
higher free energy
ATP to ADP is a ________ reaction.
Exogonic
Products have a (low/high) energy compared to the reactants
low
chemical work uses ________ energy to perform endergonic reactions
exergonic
What is phosphorylation
the transfer of a phosphate group from ATP to another molecule
Phosphate groups are ________ bonded
covalently
Two reactions are coupled when the energy needed to complete the endergonic reaction is _____ than the energy released by ATP
less
ATP hydrolysis is a great example of _______ _________
Energy coupling
What is the benefit of energy coupling regarding endergonic and exergonic reactions
energy coupling allows endergonic reactions to be coupled with exergonic reactions that result in a net exergonic reaction
What type of reaction will occur spontaneously
exergonic
What are the effects of a phosphorylated intermediate?
makes the compound less stable and increases free energy
What is the process of turning glutamic acid into glutamine
- ATP phosphorylates Glu into a phosphorylated intermediate
- ammonia displaces phosphate group by forming glutamine
What is transport and mechanical work powered by?
ATP hydrolysis
What is transport work?
ATP phosphorylates transport proteins
What is mechanical work?
ATP binds non-covalently to motor proteins and is then hydrolyzed
Energy released by _______ add phosphate to ADP to form ATP and a H2O molecule
catabolism
The breakdown of ATP into ADP and a phosphate group produces energy used for ___________
cellular work
What is a catalyst?
a chemical agent that speeds up a reaction w/o being consumed by the reaction
What is an enzyme?
a macromolecule that acts as a catalyst
Most the time an enzyme is what kind of macromolecule?
protein
What is activation energy?
the initial energy needed to start a chemical reaction
Activation energy is often supplied in the form of ______ energy
thermal
What is a transition state?
when molecules have absorbed enough energy for their bonds to break
How does a transition state affect reactants?
puts them in an unstable state
How do enzymes catalyze reactions
by lowering the EA barrier
What is the relationship between Enzymes and change in free energy
Enzymes do not change free energy they simply speed up the reaction
substrate
the reactant that an enzyme acts on
enzyme substrate complex
enzyme and substrate bonded together
What is an active site
the region on the enzyme where the substrate binds
What are the 4 ways that an active site can lower an EA barrier?
- orienting substrates correctly
- straining substrate bonds
- providing a favorable microenvironment
- covalently bonding to the substrate
What is the catalytic cycle of an enzyme ?
- substrates enter active cite
- enzyme-substrate complex
- substrates are converted to products
- products are released
- active site is available for new substrates
What effects enzyme activity?
- environmental factors
2. chemicals that specifically influence enzymes
What are cofactors?
non protein enzyme helpers
What is a coenzyme ?
an organic cofactor
What do competitive inhibitors do?
bind to the active site on an enzyme, competing with the substrate
What do noncompetitive inhibitors do?
bind to another part of the enzyme causing the enzyme to change shape
What are the effects of noncompetitive inhibitors?
they make the active site less effective
What is an allosteric regulation?
when a regulatory molecule binds to a protein on one site and affects the protein’s function at another site
What are the effects of an allosteric reaction?
either inhibit or stimulate an enzymes activity
What are most allosterically regulated enzymes made from?
polypeptide subunits
The binding of an activator stabilizes what?
the active form of the enzyme
The binding of an inhibitor stabilizes the what?
inactive form of the enzyme
What is cooperatively?
a form of allosteric regulation that can amplify enzyme activity
What is feedback inhibition?
the end product of metabolic pathway shuts down the pathway
What does feedback inhibition help prevent?
prevents the cell from wasting valuable chemical resources by synthesizing more product than is needed
T or F? some enzymes reside in specific organelles
T
T or F? some enzymes act as structural components of membranes
T
