LACL3 Flashcards
what is the 1st law of thermodynamics?
energy can be converted from one form to another, but the total energy of the universe remains CONSTANT
what is the 2nd law of thermodynamics?
all energy transformations ultimately lead to more disorder in the universe (increase entropy in the universe)
what is entropy?
randomness/chaos/ disorder in a closed system increases
what is an enclosed system?
- collection of molecules that does not exchange matter with the rest of the universe
- energy is distributed between atoms
- everything is highly organised in life (ordered and balanced)
why are cells regarded as “open systems”?
take energy from the sun and food to generate order
to generate order, they become disordered, so entropy increases
to produce order inside a cell, cells release heat which creates what?
disorder (entropy increase)
what is Gibbs Free energy?
direct measure of entropy change of the universe and how far it’s from the equilibrium
Free energy in a closed system can be defined by which 3 quantities?
- enthalpy (H): heat released to surroundings
- entropy (S): randomness and disorder
- T: absolute temperature
what is the equation of free energy?
G= H-TS
what are the 2 conditions for a spontaneous reaction to happen?
System must..
- give up energy
- become more random and increases in entropy
What do spontaneous reactions need to kickstart them?
Energy needs to be put into them ( to become more disordered)
does a spontaneous reaction release energy?
yes
how does a spontaneous reaction affect the enthalpy and entropy?
entropy: increases (-ve delta G)
enthalpy: decreases
what delta G value do spontaneous and non-spontanous reactions have?
spontaneous: -ve delta G
non-spontanoeus: +ve delta G
reactions such as formation of proteins, DNA, chemical, organs etc. will have what sort of delta G value?
+ve; biological processes require lots of order (need to be non-spontaneous= less entropy)
what process is used to carry out thermodynamically unfavourable reaction>
energy coupling
what is energy coupling exactly?
- ongoing energy cycle
- energetically favourable reactions release energy (break things down into original components) and is continuously used for energetically unfavourable reaction producing biological order (synthesising)
why is the overall entropy increasing in energy coupling?
because more molecules will be going through the energetically favourable reaction so delta G will be more negative (entropy/ disorder increases)
is breaking molecules (favourable reaction ) the “driving” part of the energy coupling cycle?
yes; it’s bigger (therefore entropy increases)
what is catabolism?
- Breaking molecules
- energetically favourable
- delta G= -ve
- release energy
eg. food molecule broken down into oxidised food source
what is anabolism?
- synthesising molecules
- energetically unfavourable
- delta G= +ve
- requires energy
e. g. molecule available in a cell changed into molecule needed by the cell (making new things)
what are activated carrier molecules?
- energy stored in them as chemical bond energy
- carry bond energy from site of energy generation (release) to site where energy is used (biosynthesis)
- readily transfer chemical groups or electrons
- serve as both source of energy and chemical groups
- store energy in an easily exchangeable form and are readily transferable
what are activated carrier molecules sometimes referred to as?
co-enzymes (e.g. ATP, NADH, NADPH)
what do coupled reactions achieve?
energetically favourable reaction drives energetically unfavourable reaction to produce activated carrier molecule to transfer energy in usable form (to prevent it from wasting and being released as heat)
define metabolism
chemical process in a living organism by which food is sued for tissue growth (energy production)
do spontaneous reactions reach equilibrium?
no; they move towards it but never reach equilibrium
what is an exergonic process?
release of energy (catabolic reaction)
what is an endergonic process?
absorption of energy (anabolic reaction)
what is each metbaolic step catalysed by?
enzymes
define coupled reaction
energetically favourable reaction is used to drive the energetically unfavourable one that produces an activated carrier molecules or some other useful energy store
describe ATP-ADP interconversions in terms of catabolic and anabolic pathways
- ATP has a higher potential energy than ADP and Pi so hydrolysis occurs; catabolic, favourable, exergonic (-ve), high entropy
- ADP to ATP condensation occurs; anabolic, unfavourable,, endergonic (+ve), low entropy
what is the most widely used activated carrier molecule?
ATP (best currency of energy)
is synthesis of ATP from ADP and Pi, energtically unfavourable
yes (synthesis, anabolic reaction)
What is catabolism in terms of complex and simple molecules?
Breaking:
from complex to simple molecules
what is anabolism in terms of complex and simple molecules?
Forming/synthesis:
from simple to complex molecules
When glucose is broken down into PEP and then pyruvate , the potential energy from PEP can take two route, what are they?
- energy released is used in pyruvate formation
OR - energy saved as potential energy in an ATP molecule
what is the most common energy conversion step?
ATP–> ADP + Pi
what is responsible for production of energy in all cells?
electron flow
define electron motive force
describing electrons can accomplish work as they pass through chemical intermediates, the difference in potential that tends to give rise to the electron current
what are some common activated carrier molecules?
- ATP; carries Pi group
- NADH/NADPH, FADH2: electrons and H
- Acetyl CoA: carries acetyl groups
- carboxylated biotin; carboxyl groups
- S-adenosylmethionine: methyl groups
spontaneous reactions summary
- -ve delta G
- energy release
- energetically favourable
- entropy increases
- NO order
- catabolic (breaks things down)
- exergonic
non-spontaneous reactions summary
- +ve delta G
- energy taken in
- energetically unfavourable
- entropy decreases
- ORDER
- anabolic (synthesises)
- endergonic
