energy Flashcards
thermal energy
chemical energy stored in bonds of molecules and kinetic energy of brownian motion
temperature
average kinetic energy of molecules
heat
flow of kinetic energy from one object/ place to another
metabolic pathways
a series of chemical reactions resulting in a set product, each catalyzed by different enzymes
catabolism
energy releasing pathways (degradative)
Anabolism
pathways that consume energy to build complex molecules (biosynthetic)
first law of thermodynamics
conservation of energy, energy cant be created or destroyed, only converted from one form to another
second law of thermodynamics
all systems tend to entropy(chaos)
all systems tend to entropy unless
energy is being put in
transforming energy results in
loss of organized, usable energy as heat
1865 Philosophical Society of Zurich presentation Clausius concludes:
The entropy of the universe tends to a maximum.’
theClausius statement
Heat can never pass from a colder to a warmer body without some other change
Biological version
enzyme mediated chemical reactions cause the change that decreases the entropy of a substance
spontaneous processes occur on their own to
increase disorder
Heat flows from
high concentration of heat to low
The universe tends toward
chaos (entropy)
Second law
Without the input of E. disorder…
increases, dead things decompose
Solar E. is added to ecosystems via
photosynthesis
Conversion of E from one form to another results in
loss of usable energy in form of heat
only – percent of energy is passed up the food chain
10 percent
G stands for
free energy
change in G indicates
if a reaction will be spontaneous
negative ΔG
increases entropy
spontaneous
new molecules are lower E… degradative
exergonic pathway
Positive ΔG
decreases entropy = require an input of energy to occur (synthesizes molecules that are higher E)
endergonic pathway
ΔG = ΔH - T ΔS
ΔH = change in enthalpy ΔS = change in entropy T = absolute Temperature in Kelvin ΔG = change in Gibbs free energy
catabolism chart
Degredative Breaks down large mol. Hydrolysis rxns Increases entropy by Releasing E. (- ΔG) Exergonic Cellular respiration
anabolism chart
Biosynthetic Builds large molecules Condensation rxns Decreases entropy by Storing E in mol. (+ ΔG) Endergonic Photosynthesis Refugees energy to work
Energy Coupling
Exergonic rxns power endergoninc rxns
Energy is transferred via ATP
Adenosine triphosphate
Nucleoside used in RNA (ribose + adenine (sugar and base)
Plus 3 phosphates
Hydrolysis (breaking) of ATP releases inorganic phosphate
inorganic phosphate
(Pi)+ 13 kcal/mol
Adenosine triphosphate Proteins can harness that E to
transport molecules (protein pumps) move things ( motor proteins) drive endergonic rxns
ATP drives endergonic rxns by
Substrate level phosphorylation
Substrate level phosphorylation
enzyme transfers one Phosphate from ATP to a molecule creating an Unstable intermediate
Unstable intermediate
is a higher energy mol.
more likely to react spontaneously…releasing the Pi
Glu + NH3= endergonic (+G)
So in body Glu forms an unstable phosphorylated intermediate first
Then the Pi is replaced
by the lower energy NH3
Combined the reactions
are exergonic (-G) & therefore spontaneous
ATP moves proteins by
step one
ATP is hydrolyzed and protein is phosphorylated…then Pi is released result: protein changes its structure
ATP moves proteins by
step two
ATP binds to protein …hydrolyzing ATP releases energy that causes protein to change shape
Enzymes
Proteins Biological catalysts Speed reactions but are NOT a reactant (not used up) lower activation energy do NOT alter overall ΔG
a —– reaction requires a higher activation energy than does a—-
an uncatalyzed reaction requires a higher activation energy than does a catalyzed reaction
is there a difference between free energy of catalyzed and uncatalyzed reactions
no,no difference between catalyzed and uncatalyzed reactions
substrate
reactant enzyme binds
active site
pocket where substrate fits into enzyme
induced fit
alteration of substrate or active site to make a better fit between them
Allosteric site
pocket other than active site where activators & inhibitors can bind
Activators
increase the activity of enzyme … stabilize enzyme in active form
inhibitors
block activity of enzyme
…stabilize enzyme in inactive form
Activation Energy lowered by…
aligning molecules favorably
putting stress on bonds in molecule
creating favorable microenvironment
Allosteric Regulator molecules all bind to
allosteric site
activator molecules stabilize enzyme in
active form
inhibitor molecules
stabilize enzyme
in
inactive form
active sites based on
shape, size, pH, polarity, charge
Substrate held in place by
weak interactions
(H-bonds, ionic bonds)enzymes catalyze
one reaction
Competitive inhibitors
mimic substrate, bind active site covalently & inactivate enzyme
Feed-Back Inhibition
allosteric
The end-product of a pathway shuts down the first enzyme of the pathway that creates it
prevents overproduction of products
cofactors
Non-protein molecules/atoms needed for enzymes to work
inorganic cofactors
Inorganic cofactors include Zn Fe & Cu ions
Organic cofactors are
called coenzymes
include many vitamins & vitamin derivatives and nucleotides like NAD+ & FAD
things that influence reaction rates
Concentration of enzymes/coenzymes/cofactors
pH
Temperature
Concentration of substrate
Concentration of allosteric molecules
Localization of reactions (compartmentalization)
Denatured enzymes or altered enzyme structure
denatured
if temp and pH change beyond enzymes optimum, shape of enzyme changes, this affects the active site and means the enzyme will no longer work
what does increasing temp do
Increases KE
Increases reaction rate
Excessive Temperature denatures enzyme by
Breaking H bonds that
Hold enzyme in its secondary structure
Does heat change chemical energy
No, only breaking bonds affects it
Adding energy to ecosystems does what
Maintains order
What is free energy
En hey that can perform energy, is available
Order
Lots of energy in molecule
Disorder
Less energy in molecule
Exergonic pathway
Giving off energy kinda like expthermic
Change in G is
Difference between what it starts with (products) and ends with (reactants)
For exergonic reactions explain energy relationship
Reactants have more energy than products (lose energy)
What is activation energy
The energy the reactants gain from the environment until the reaction can run
Endergonic pathway
Put in energy
Endergonic reaction reaction relationship with energy
Reaction energy is less than the products (gains energy)
What increases enthalpy (order)
When increasing concentration and building bigger molecules
What increase entropy
Spread molecules out and break them apart
Which one is spontaneous: anabolic or catabolic
Catabolic
What molecule is more stable
One with less energy
Hydrolyzed ATP goes to
ADP+P
If want to include an enzyme in a reaction put it where
Over the yield sign
What is the only difference between catalyzed and uncatalyzed reactions
The activation energy
How can competitive inhibitors be overcome
can be overcome by vast increase in substrate concentration
