Metabolism and ATP Flashcards
An organism’s metabolism transforms
matter and energy,
An organism’s metabolism is
subject to
the laws of thermodynamics
The free-energy change of a reaction tells us
whether or not the reaction occurs spontaneously
ATP powers cellular work by
coupling exergonic reactions to endergonic reactions
Enzymes speed up metabolic reactions by
lowering energy
barriers
Regulation of enzyme activity helps
control metabolism
A living cell is a
miniature chemical factory where
thousands of reactions occur
The cell extracts energy
stored in sugars and other
energy-containing organic molecules
The cell extracts energy and applies
energy to perform work
Metabolism
the totality of an organism’s chemical
reactions
metabolism is an _______ from _____
emergent property and interactions between molecules in cell
Metabolic pathways
begin with a specific molecule
(substrate or reactant) and end with a product
Each step in the metabolic pathways us
catalyzed by a specific enzyme
Catabolic pathways
release energy by breaking down
complex molecules into simpler compounds
example of catabolic pathways
Cellular respiration
how is Cellular respiration an example of a catabolic pathway
breakdown of glucose in the
presence of oxygen
Anabolic pathways
consume energy to build complex
molecules from simpler ones
Anabolic pathway example
Synthesis of protein from amino acids
Bioenergetics
the study of how organisms manage
their energy resources
Energy
the capacity to cause change
Energy exists in ______ and some can _____
various forms and perform
work
Energy can be converted
from one form to another
Kinetic energy
energy associated with motion
thermal energy is also known as
heat
Heat (thermal energy)
kinetic energy associated with
random movement of atoms or molecules
Potential energy
energy that matter possesses
because of its location or structure
Chemical energy
potential energy available for release
in a chemical reaction
Thermodynamics
the study of energy transformations
two types of systems
- open system
- isolated system
isolated system
unable to exchange energy or
matter with its surroundings
open system
energy and matter can be transferred
between the system and its surroundings
organisms are _____ systems
open
first law of thermodynamics
the amount of
energy in the universe is constant
how is the amount of
energy in the universe is constant
Energy can be transferred and transformed, but it cannot be
created or destroyed
what is first law of thermodynamics also known as
principle of conservation of energy
During every energy transfer or transformation, some energy is
unusable, and often lost as heat
The second law of thermodynamics
Every energy transfer or transformation increases
entropy (disorder) of the universe
Living cells convert what to what
organized forms of energy to heat
Spontaneous processes
without energy input
For a process to occur without energy input
it must increase entropy of universe
Spontaneous processes can happen
quickly or slowly
Cells create ordered structures from
less ordered materials
Cells create ordered structures from less ordered materials
Requires the input of energy
Organisms also replace
ordered forms of matter and
energy with less ordered forms
- Energy flows into an ecosystem in _____ and exits in ____
form of light
form of heat
Evolution of more complex organisms
does not violate
the second law of thermodynamics
Entropy (disorder) may _____ in an organism, but universe’s total entropy ____
decrease and increases
Biologists want to know
which reactions occur
spontaneously and which require input of energy
An unstable system is
rich in free energy.
An unstable system has a tendency to
change spontaneously to a more stable state
how does the free-energy concept apply on a molecular scale
to the physical movement of molecules
known as diffusion
less free energy means what (2)
- more stable
- less work capacity
Chemical reactions also involve
free energy.
When catabolic pathways break down complex organic molecules what can a cell do
harness the free energy stored in the molecules to perform
work
Free energy
-It is the amount of energy that is available to do work.
what is a criterion for spontaneous change
Free energy
G
Free energy
Free energy is related to the systems
total energy and entropy
H
enthalpy of total energy
S
entropy
T
Temperature in K
Free Energy equation
G = H-TS
Free energy (g) is proportional to the
system’s energy available to do work
free energy is the difference between
the total energy (enthalpy) and
the energy not available for doing work (TS)
The maximum amount of usable energy that can be harvested from a particular reaction is
the system’s free energy change from the
initial to the final state.
Gibbs-Helmholtz equation
change in free energy (ΔG) at a constant Temp and pressure
ΔG
change in free energy
ΔH
change in total energy
the total energy is also known as
enthalpy
ΔS
change in entropy
T
absolute temp in K
how to calculate Kalvins
(Degree Celius + 273)
ΔG equation
ΔG = ΔH – TΔS
The living system’s free energy is
the energy that can do work
when temperature and pressure are uniforms,
spontaneous processes have a
negative ∆G
what can spontaneous processes be harnessed to do
perform work
During a spontaneous change, free energy ____ and the stability of a system ____
decreases and increases
- Free energy is a measure of a
system’s instability
system’s instability
tendency to change to a more stable state
Equilibrium is a state
of maximum stability
A process is spontaneous and can perform work only
when it is moving toward equilibrium
more free energy =
- higher G
- less stable
- greater work capacity
In a spontaneous change
- free energy of the system decreases
- system becomes more stable
- released free energy can be used to do work
the final result of the change
- less free energy
- lower G
- more stable
- less work capacity
Based on their free energy changes, all chemical reactions
classified as exergonic or endergonic
relationship between chemical equilibrium and the free energy change (ΔG) of a reaction
- As a reaction approaches equilibrium, the free energy of the system decreases
- When a reaction is pushed away from equilibrium, the free energy of the system increases
- When a reaction reaches equilibrium, ΔG = 0
When a reaction reaches equilibrium, ΔG = 0
no net change in the system
When a reaction is pushed away from equilibrium, the free energy of the system increases
non-spontaneous and
endergonic reaction
As a reaction approaches equilibrium, the free energy of the system decreases
spontaneous and exergonic reaction
Reactions can be classified based on their free energy changes
Exergonic reaction
Endergonic reaction
Exergonic reaction
a reaction that proceeds with a net
loss of free energy.
Endergonic reaction
an energy-requiring reaction that
proceeds with a net gain of free energy;
a reaction absorbs free energy from its surroundings
Endergonic reaction
Chemical products have less free energy than the reactant molecules
Exergonic reaction
Reaction is energetically downhill
Exergonic reaction
Spontaneous reaction
Exergonic reaction
ΔG is negative
Exergonic reaction
ΔG is the maximum amount of work the reaction can perform
Exergonic reaction
Products store freer energy than reactants
Endergonic reaction
The reaction is energetically uphill
Endergonic reaction
Non-spontaneous reaction
requires energy input
Endergonic reaction
ΔG is positive.
Endergonic reaction
+ΔG is the minimum amount of work required to drive the reaction
Endergonic reaction
- An exergonic reaction proceeds
with a net release of free energy and is spontaneous
- Exergonic reaction is
spontaneous
Energy is released during
the progress of an exergonic reaction.
The amount of energy released is delta G
less than zero
Exergonic reaction
The exergonic reaction is the
difference between the ____ free energy of
the reactants and the ____ free energy of
the products
higher and the lower
An endergonic reaction
absorbs free energy from its
surroundings and is nonspontaneous
nonspontaneous
Endergonic reaction
Energy is required during the progress
- Endergonic reaction
The amount of energy required is delta G
greater than zero
- Endergonic reaction
Endergonic reaction is the
difference between the ____ free energy
of the reactants and the ____ free energy
of the products
lower and higher
Reactions in a closed system
eventually, reach equilibrium
and then do no work
Cells are
not in equilibrium and open systems
experiencing a constant flow of energy and matter
- Defining feature of life
is that metabolism is never at
equilibrium
Catabolic pathway in a cell
releases free energy in a series
of reactions
If a chemical process is exergonic the reverse process
must be endergonic
For each mole of glucose oxidized in the exergonic process of cellular respiration
2870 kJ are released
To produce a mole of glucose, the endergonic process of photosynthesis requires
energy input of 2870 kJ
The individual steps of respiration in isolation would
come to equilibrium and the cellular work would cease
in respiration, there is a series of drops in free energy between
glucose, the start material and the metabolic wastes at the end
with the steps, respiration will
never reach equilibrium as long as the organism lives
with multiple steps, the _____ becomes the _____ for the next and the _____ are expelled from the cell
- product
- waste
- metabolic wasts
three kinds of cellular work
- chemical
- transport
- mechanical
To do work, cells manage energy resources by
energy coupling
energy coupling
use of an exergonic process to drive an endergonic one
Most energy coupling in cells is mediated by
ATP (adenosine triphosphate)
cell’s energy shuttle
ATP
ATP has what nitrogen base
adenine
Bonds between the phosphate groups of A T P can be broken
by hydrolysis
- Energy is released from ATP with
the terminal phosphate bond of ATP broken
The release of energy comes from the ATP molecule is
chemical change to a state of lower energy, not from the phosphate bonds themselves
cilia beating
mechanical work
the contraction of the muscle cells
mechanical work
the movement of the chromosomes during
cellular reproduction
mechanical work
the pumping of substances across
membranes against the direction of spontaneous movement
transport work
the pushing of endergonic reactions that would
not occur spontaneously
chemical work
synthesis of polymers from monomers
endergonic
ATP drives endergonic reactions by
phosphorylation
phosphorylation
transferring a phosphate group to some other molecule
phosphorylated intermediate
The recipient molecule after receiving the phosphate group
ATP is a ______ regenerated from _____
renewable resource and adenosine
diphosphate ADP
Energy to phosphorylate ADP comes
catabolic reactions in the cell
Catalyst
chemical agent that accelerate a reaction without being permanently changed in the process
Enzymes
are catalytic proteins that change the rate of a
reaction without being consumed by the reaction
Are all enzymes catalysts
YES
Are all catalysts enzymes
NO
Transition state
unstable condition of reactant molecules
that have absorbed sufficient free energy to react
energy of activation, or activation
energy
The initial investment of energy for starting a reaction – the energy required to break bonds in the reactant molecules
example of an enzyme-catalyzed reaction
Hydrolysis of sucrose by sucrase
Every chemical reaction between molecules involves
bond breaking and bond forming
Initial energy needed to start a chemical reaction
activation energy
Activation energy is often supplied in form of
thermal energy that reactant molecules absorb from their surroundings
Enzymes catalyze reactions
by lowering activation energy barrier
Enzymes do not affect
change in free energy (∆G)
The reactant that an enzyme acts
substrate
An enzyme binds to its substrate to form an
enzyme-substrate complex
the reaction catalyzed by each enzyme is very specific
from the enzyme-substrate complex
The active site
is the region on an enzyme where the
substrate binds
Induced fit
a substrate brings chemical groups of active
site into positions that enhance their ability to catalyze reaction
The active site can lower an EA barrier by
- Orienting substrates correctly
– Straining bonds in the substrate molecule
– Providing a favourable microenvironment
– Covalently bonding to the substrate
In an enzymatic reaction, the substrate
binds to the active site of the enzyme
how are substrates held together in the active site
by weak interactions
hydrogen or ionic bonds
An enzyme’s activity can be affected by
temperature
pH
pressure
Chemicals that specifically influence the enzyme
Optimal conditions favour the most
active conformation (shape) for the enzyme
optimal temp for typical human enzyme
37 degree Celcius
Stomach enzyme (Pepsin) optimal PH
2
Intestinal enzyme (Tryposin) optimal PH
8
Cofactors
nonprotein enzyme helpers
cofactors may be
inorganic
or organic
inorganic cofactor
such as a metal in ionic form
coenzyme
organic cofactor
coenzyme example
vitamins
Competitive inhibitors
bind to the active site of an
enzyme, competing with substrate
Noncompetitive inhibitors
bind to an enzyme at a
separate site from the active site
Noncompetitive inhibitors results in
a conformational change in the enzyme that makes the active site less effective
Examples of inhibitors include
toxins, poisons, pesticides,
and antibiotics
antibiotics works more on
bacteria
ANIMAL intermediate energy
glucose and sugar
ANIMAL immediate energy
ATP
ANIMAL long-term energy
Fat and adipose cells
PLANT intermediate energy
Glucose
PLANT immediate energy
ATP
PLANT long-term energy
oils
photosynthesis is endergonic or exergonic
endergonic reaction
cellular respiration is endergonic or exergonic
exergonic reaction
more complex molecules have more energy because
the energy stored is in the bonds
Downhill metabolic pathway
Energy is released by the downhill reactions of catabolic pathways
uphill metabolic pathway
energy is stored and then used to drive uphill reactions of anabolic pathways
a process on its own that leads to a decrease in entropy
Nonspontaneous process
Organisms are ____ entropy
low
The greater the decrease in free energy,
the greater the amount of work that can be done
Why does heat not work well in biological systems?
a. High temps denature proteins and kill cells
b. Heat would speed up ALL reactions not just specific ones
Inhibitors can attach to the enzyme by covalent bonds
irreversible
Most bind to the enzyme by weak interactions
reversible
A cell must be able to control when and where its various enzymes are active
Either by switching on and off the genes that encode specific enzymes
Regulating the activity of enzymes once they are made
Endergonic or Exergonic
Endergonic
Endergonic or Exergonic
Exergonic
enzymes are _____ encoded by ____
proteins and genes
changes or _____ leads to changes in enzyme’s ______
mutations and amino acids
altered amino acids may alter enzyme’s
substrate specificity
what would result if a cell’s metabolic pathways were not regulated
chemical chaos
how does a cell regulate its metabolism
- switching on or off genes that encode specific enzymes
- regulating activity of enzymes
Allosteric regulation
may either inhibit or stimulate an enzymes activity
Allosteric regulation occurs when a
regulatory molecule binds to a protein at one site and affects the protein’s functionm at another site
Most allosterically regulated enzymes contain
multiple polypeptide subunits
Each enzyme has
active and inactive forms
Binding of an activator
stabilizes the active form of an enzyme
- Binding of an inhibitor
stabilizes the inactive form of an enzyme
Cooperativity
is a form of allosteric regulation that can
amplify enzyme activity
In feedback inhibition,
the end product of a metabolic pathway shuts down the pathway
ATP powers cellular work by
coupling exergonic
reactions to endergonic reactions
ATP drives endergonic reactions by
transfer of the phosphate group to specific reactants
cell respiration (catabolic pathway) drives the
regeneration of ATP from ADP
