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)
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Bones23
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Skin28
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Carbohydrates 121
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Carbohydrates 263
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Nerves 158
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Tissues 169
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Tissues 272
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Carbohydrates 5: Citric Acid Cycle48
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Carbohydrates 6: Terminal respiration67
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Nerves 237
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Nerves 337
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LACL 138
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LACL 238
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Nerves 437
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Enzymes 146
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Enzymes 265
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LACL342
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LACL441
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Sensory Receptors 148
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Sensory Receptors 241
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Sensory receptors 326
