life @ cellular level - thermodynamics of life 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, i.e. increase the entropy
Gibbs Free Energy is a useful, energy of a closed system, what 3 quantities can it be defined by?
Enthalpy (H) - heat/energy released to surroundings
-Entropy (S) - randomness/disorder
Absolute temperature (T)
G=H-TS
Gibbs free energy can be used to define the spontaneity of a reaction, when do they occur?
if a system:
Gives up energy e.g. water runs downhill
Becomes more random and increases in entropy
why does spontaneous energy changes have a negative value for their change in free energy?
A spontaneous process must decrease enthalpy (H) and/or increase entropy (S)
what is reaction coupling?
it’s a strategy used by cells, in which an energetically favourable reaction is linked with an energetically unfavourable reaction
what does ΔG = 0 mean?
the reaction is at an equilibrium which is incompatible with life.
Reactions usually do not reach equilibrium in our bodies as they are open systems i.e. energy passes from the environment to the organism and back to the environment.
what is the dynamic steady state?
Where the rate of input/supply equals the rate of output/removal
when does a system reach a Dynamic Steady State?
When a = b (equal reaction rates) the system is in a dynamic state because the intermediate molecule does not change concentration
what is metabolism?
The chemical process in a living organism by which food is used for tissue growth
what is catabolism and anabolism?
Catabolism is the breaking-down aspect of metabolism.
Anabolism is the building-up aspect of metabolism
what is the form of energy harvested from catabolic pathways?
ATP
what is the ATP energy harvested from catabolic pathways used in?
anabolic pathways to form complex molecules (proteins, DNA, Fatty acids.. etc.)
what is metabolism catalysed by?
enzymes
why do spontaneous reactions move toward equilibrium but do not reach it?
because the body is an open system where the products are used in subsequent reactions
since spontaneous reactions aren’t instantaneous, what do they depend on?
the enzymes function by selectively altering the rate of metabolic reactions.
what are intermediary metabolites?
The molecules that are used in link between catabolic and anabolic reaction pathways e.g. ATP, ADP, NADH, NAD+
what is ATP hydrolysis?
a catabolic reaction used to release free energy
collected to do energetically unfavourable reactions (+ΔG)
what is an exergonic process?
one in which there is a positive flow of energy from the system to the surroundings
how does the exergonic, catabolic (break-down) pathway ‘save’ free energy?
within a system by forming ATP.
what is an endergonic process?
is a reaction that requires energy to be driven e.g. photosynthesis
how is the endergonic, anabolic (build-up) pathway ‘supplied’ with free energy?
within a system from converting ATP to ADP
what reactions do ATP - ADP interconversions involve? and why?
ATP hydrolysis and ADP condensation
to ensure the flow of free energy between pathways
What’s the difference between ADP Condensation and ATP Hydrolysis thermodynamically?
ATP has a higher potential energy than ADP/Pi
ATP Hydrolysis occurs with a decrease in Free Energy, it is catabolic/exergonic.
describe an intermediate process in glucose metabolism (phosphoenolpyruvate):
Phosphoenolpyruvate (PEP) is converted to pyruvate
releases potential energy which is stored in the form of ATP by an ADP-ATP interconversion through phosphoryl transfers.
what driving force is the ATP - ADP interconversions behind?
muscle contractions and membrane potentials which can store or release energy in the form of phosphoryl group transfer between molecules
what do cellular redox reactions use?
Metabolic intermediaries as electron carrier molecules such as NAD+ and FAD+, act as coenzymes in metabolic pathways to facilitate fuel oxidation and biosynthesis reactions.
