Chapter 8: An Introduction to Metabolism Flashcards
is a miniature chemical factory where
thousands of reactions occur
the living cell
extracts energy stored in sugars
and other fuels
cellular respiration
Cells apply this energy to perform work
the energy produced for cellular respiration
is the totality of an organism’s chemical reactions
metabolism
is an emergent property of life that arises from orderly interactions between molecules
metabolism
begins with a specific molecule and ends with a product
metabolic pathway
release energy by breaking down complex molecules into simpler compounds
catabolic pathways
an example of catabolic pathways is
Cellular respiration, the breakdown of glucose
in the presence of oxygen,
consume energy to build
complex molecules from simpler ones
anabolic pathways
example of anabolic pathways
the synthesis of protein from amino
acids
is the study of how energy flows
through living organisms
bioenergetics
is the capacity to cause change
energy
Energy associated with motion
kinetic energy
is the kinetic energy associated with
random movement of atoms or molecules
thermal energy
is thermal energy in transfer between objects
heat
is energy that matter possesses
because of its location or structure
potential energy
is potential energy available for release in a chemical reaction
chemical energy
is the study of energy
transformations
thermodynamics
is unable to exchange energy or
matter with its surroundings
isolated system
energy and matter can be
transferred between the system and its surroundings
open system
what kind of systems are organisms
open
proceeds with a net release of free energy and is spontaneous
exergonic reaction
absorbs free energy from its surroundings and is non spontaneous
endergonic reactions
what happens to reactions in closed systems
eventually reach equilibrium and can then do no work
what is special ab metabolism in life
it is never at equilibrium
three main kinds of work
chemical
transport
mechanical
pushing endergonic reactions
chemical work
pumping substances against the direction of spontaneous movement
transport work
contraction of muscle cells
mechanical work
how cell manage energy resources
energy coupling
the use of an exergonic process
to drive an endergonic one
energy coupling
most energy coupling is meditated by what
ATP
the chemical breakdown of a compound due to reaction with water.
hydrolysis
how is cellular work powered?
hydrolysis of ATP
what can be used to drive an endergonic reaction
the energy from the exergonic reaction of ATP hydrolysis
transferring a phosphate group to some other
molecule, such as a reactant
phosphorylation
how does ATP drive endergonic reactions?
phosphorylation
the molecule that receives the phosphate group is called
phosphorylated intermediate
is a renewable resource that is regenerated by
addition of a phosphate group to adenosine
diphosphate ()
ATP
what regenerates ATP?
addition of a phosphate group to adenosine
diphosphate (ADP) (phosphorylate - ing the ATP)
where does the energy come to phosphorylate ATP come from
catabolic reactions
is a chemical agent that speeds up a
reaction without being consumed by the reaction
catalyst
is a catalytic protein
enzyme
Every chemical reaction between molecules involves what
bond breaking and bond forming
The initial energy needed to start a chemical
reaction is called the free energy of activation, or
activation energy (EA)
often supplied in the form of
thermal energy that the reactant molecules absorb
from their surroundings
activation energy (EA)
speed up specific reactions by lowering the EA barrier
catalysis
hasten reactions that would occur
eventually
enzymes
The reactant that an enzyme acts on is called the enzyme’s
substrate
The enzyme binds to its substrate, forming an
enzyme-substrate complex
example of a enzyme
sucrase
how is activation energy often supplied
thermal energy
how do catalysis speed up specific reactions
by lowering the activation energy barrier
is the region on the enzyme where
the substrate binds
active site
brings chemical groups of
the active site into positions that enhance their ability
to catalyze the reaction
induced fit of a substrate
The active site can lower an EA barrier by what
orienting substrates correctly
straining substrate bonds
providing a favorable microenvironment
covalently bonding to the substrate
how can the rate of enzyme-catalyzed reaction can be sped up
increasing substrate
When all enzyme molecules have their active sites engaged, the enzyme is what
saturated
how do you speed up a saturated reaction rate
adding more enzyme
An enzyme’s activity can be affected by
- general environmental factors, such as
temperature and pH - chemicals that specifically influence the
enzyme
are nonprotein enzyme helpers
cofactors
An organic cofactor is called a
coenzyme
bind to the active site
of an enzyme, competing with the substrate
Competitive inhibitors
bind to another part of an enzyme, causing the enzyme to change shape and making the active site less effective
Noncompetitive inhibitors
examples of inhibitors
toxins, poisons,
pesticides, and antibiotics
Chemical chaos would result if what
a cell’s metabolic pathways were not tightly regulated
may either inhibit or stimulate an enzyme’s activity
Allosteric regulation
occurs when a regulatory molecule binds to a protein at one site other than the enzyme’s active site and affects the protein’s
function at another site
Allosteric regulation
most allosterically regulated enzymes are made from
polypeptide subunits
stabilizes the active form of the enzyme
The binding of an activator
stabilizes the inactive form of the enzyme
The binding of an inhibitor
is a form of allosteric regulation that
can amplify enzyme activity
cooperativity
what is the exception for cooperativity
the substrate itself is the regulator and regulation is induced by binding in one of the
active sites
how is cooperativity allosteric
because binding by a substrate to one active site affects catalysis in a different active site
the end product of a
metabolic pathway shuts down the pathway
feedback inhibition
prevents a cell from wasting chemical resources by synthesizing more product
than is needed
Feedback inhibition
