Energy

Question 1

Why do things happen ?

Answer 1

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

Question 2

where is energy present in biology ?

Answer 2

homeostasis
organisation
metabolism
growth
adaptation
response to stimuli
life is a non-equilibrium process

Question 3

Where does energy come from ?

Answer 3

almost all comes from sunlight
few organisms get energy from sun-independent chemical sources

Question 4

What is energy ?

Answer 4

May be divided into potential and kinetic
physical description involves capacity to do work
f=ma
e= fd

Question 5

What is the 1st law of thermodynamics ?

Answer 5

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

Question 6

What is the first main law of energy ?

Answer 6

it is not created or destroyed
a decrease in the systems energy must be matched by an increase in the energy of the surroundings

Question 7

How do organisms harness energy ?

Answer 7

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

Question 8

Energy for covalent binding ?

Answer 8

??
molecule is stabilised by attraction between electrons and protons

Question 9

What is chemical heat transfer ?

Answer 9

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

Question 10

Calorimetry and how it works ?

Answer 10

change in heat =mxCxchange in temp

C=specific heat capacity

Question 11

What are the enthalpy chnges of reactions ?

Question 12

How are enthaplies of reactions determined by ?

Answer 12

Bond enthalpies
enthalpy is required to break bonds
enthaply released by bond formation

Question 13

What is enthalpically downhill ?

Answer 13

products of exothermic reactions have stronger bonds than the reactants

Question 14

What is enthalpically uphill?

Answer 14

products of endothermic reactions have weaker bonds than the reactants

Question 15

What is a spontaneous endothermic process ?

Answer 15

NaHCO3–>NaHCO
bonds are getting weaker

Question 16

entropy S

Answer 16

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

Question 17

The 2nd law of thermodynamics ?

Answer 17

Difficult to measure the whole universe!

We need to focus on the system.

Question 18

What is Gibbs free energy ?

Answer 18

change in G sys describes the energy that may be used to do work

Question 19

What is the driving force of a reaction ?

Answer 19

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

Question 20

What are standard thermodynamic conditions ?

Answer 20

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

Question 21

How does the free energy of ATP hydrolysis work ?

Answer 21

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.

Question 22

What is Le Chateliers principle ?

Answer 22

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

Question 23

Gibbs free energy and equilibrium ?

Answer 23

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° ́

Question 24

What is the reaction quotient Q ?

Question 25

how do we measure things ?

Answer 25

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

Question 26

What are redox reactions ?

Answer 26

electron transfer reactions
very common in bio

Question 27

How do you calculate oxidation numbers in organic compounds ?

Answer 27

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

Question 28

What carries high energy electrons ?

Answer 28

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