Energy Flashcards
Why do things happen ?
why certain reaction possible
spontaneous/thermodynamically favourble
process moves towards eqm their lowest energy state
energy can be transferred and take different
energy can be transferred and take different forms
eqm ultimately depends on the distribution of energy
where is energy present in biology ?
homeostasis
organisation
metabolism
growth
adaptation
response to stimuli
life is a non-equilibrium process
Where does energy come from ?
almost all comes from sunlight
few organisms get energy from sun-independent chemical sources
What is energy ?
May be divided into potential and kinetic
physical description involves capacity to do work
f=ma
e= fd
What is the 1st law of thermodynamics ?
energy may be transferred as heat (q) or work (w)
U=q +w
easiest to study in ideal gases which only possess kinetic energy
pV=nRT
What is the first main law of energy ?
it is not created or destroyed
a decrease in the systems energy must be matched by an increase in the energy of the surroundings
How do organisms harness energy ?
chemically
using metabolic processes to get and release chemical energy to do work?release energy
linked to potential energy -binding energy
energy absorbed when chemical bonds broken
energy is relesed when chemical bonds are formed
Energy for covalent binding ?
??
molecule is stabilised by attraction between electrons and protons
What is chemical heat transfer ?
chnage in enthalpy is the change in U at constant pressure
meaure this by energy change by measuring heat flow into or out of the process
Calorimetry and how it works ?
change in heat =mxCxchange in temp
C=specific heat capacity
What are the enthalpy chnges of reactions ?
How are enthaplies of reactions determined by ?
Bond enthalpies
enthalpy is required to break bonds
enthaply released by bond formation
What is enthalpically downhill ?
products of exothermic reactions have stronger bonds than the reactants
What is enthalpically uphill?
products of endothermic reactions have weaker bonds than the reactants
What is a spontaneous endothermic process ?
NaHCO3–>NaHCO
bonds are getting weaker
entropy S
is a measure of energetic disorder
and how many ways energy can be distributed in a system
the higher the entropy of a system the less able the energy is to do work
entropy is related to heat and temp
enthalpic heat change=Tx change in S under reversible conditions
The 2nd law of thermodynamics ?
Difficult to measure the whole universe!
We need to focus on the system.
What is Gibbs free energy ?
change in G sys describes the energy that may be used to do work
What is the driving force of a reaction ?
for spontaneous reaction change in G < 0
for non-spontaneous reaction change in G>0
at eqm change in G =0
change in G depends on amounts and concentration
What are standard thermodynamic conditions ?
all aqeous conc 1M
all gases 1 atm partial pressure
temp not specified by usually 298 K
standard biological conditions
all same except proton conc -> 1x10-7
How does the free energy of ATP hydrolysis work ?
ATP hydrolysis is the catabolic reaction process by which chemical energy that has been stored in the high-energy phosphoanhydride bonds in adenosine triphosphate (ATP) is released after splitting these bonds, for example in muscles, by producing work in the form of mechanical energy.
What is Le Chateliers principle ?
if conc of reactants are increased the reaction is driven to the right
so delta G decreases
the futher the reaction is from eqm the more the reaction is driven towards eqm
Gibbs free energy and equilibrium ?
Δ G determines spontaneity
Δ G < 0 the reaction is spontaneous (goes left to right)
Δ G > 0 the reaction is non-spontaneous (goes right to left)
Δ G = 0 the reaction is at equilibrium
Δ G varies to according to conc of reactants
Δ G varies according to conc
example of ATP hydrolysis
Importantly, under standard conditions Δ G = Δ G°
under biological standard conditions Δ G = Δ G° ́
What is the reaction quotient Q ?
how do we measure things ?
ou can get Q and K by measuring concentrations
by titrations,spectrophotmetry
measure
also measuring delta G and delta G for redox reactions
electron transfer-changes in redox reactions-changes in oxidation numbers-measuring voltage
What are redox reactions ?
electron transfer reactions
very common in bio
How do you calculate oxidation numbers in organic compounds ?
Similar to calculating formal charge if identical atoms bound to each other.
In a bond between non-identical atoms, both bonding electrons are assigned to the more electronegative atom.
This means that O atoms in a compound have ON = -2
H atoms in a compound have ON=+1
What carries high energy electrons ?
NADH,NADPH,FADH2
described as activated carriers of electrons
when compared with ATP;activated carrier of phosphate
ATP hydrolysis NOT redox reaction
P remains in 5+ oxidation state
