BIOL 201 Lecture Notes - Lecture 1: Glycogen, Tuberculosis, Protein Structure
Living things convert energy from one form to another, but never created or destroyed!
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Ex. Plants take energy from photon, convert to chemical energy through PS
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Animals do NOT consume energy! (First law of thermodynamics!)
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Ex. You can store chemical energy in the form of more biomass
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Caveat: organisms store energy during growth
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ATP= energy currency of cells
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Conversions of chemical bonds into heat and work
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~20% of genome devoted to metabolism
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Number 2: organisms store energy temporarily during activity
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Metabolism: the science of energy conversions
We’re converting a simple molecule into a complex organism
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Seems to go against 2nd law of thermodynamics that disorder and entropy are always increasing in the universe!
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Not all energy is equal! It can differ in its quality
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Doesn’t work both ways
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Potential E of mass on pulley is very high quality energy, has high amount of order
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Energy in water tank low quality, due to random motion of molecules
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Joule showed that increase in water temperature (thermal E) was directly related to height of mass spinning paddles from pulley
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Are we getting something from nothing?
Consume high quality energy (food, chemical bonds) and convert it into low quality energy (heat and work)
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Quality can never be spontaneously recovered!
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Living organisms convert high quality energy into low quality energy!
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Gibbs: defined total energy as ENTHALPY (H)
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G= free energy or available energy, or H - “unavailable energy”
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G =H - TS (total energy minus that which is no longer available
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Entropy: disorder, number of states in which system exists (Microsystems)
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The quality of energy depends on how much is “free”
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Cells capture the free energy released by atp hydrolysis to create order
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G = GFINAL - GINITIAL
G = H - T S **for an isolated system, H = 0
Entropy increases; S > 0
The change in Free Energy determines whether a process occurs spontaneously
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G < 0 for spontaneous processes!
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Standard free energies are ADDITIVE!
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If not standardized, must convert to conditions of reaction under study
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A
→
B
→
C
G° A
→ C
= G° A
→ B
+ G° B
→ C
Free Energy values are “standardized” ( G°’) where T=298K, P= 1 atm, pH = 7.0, [ ]’s = 1M
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Animals consume ENERGY QUALITY
So how do you ever make it over a transition state?
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Catalysts lower energy of transition state
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Always have some reactants and products in equilibrium state
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Delta G of transition state is positive?
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Amount of free energy a molecule has fluctuates
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Ex. Trk dimer can spontaneously undimerize, takes a few tries to form dimer
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Interaction of surrounding molecules that collide with protein to alter
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free energy state
If fluctuations exceed threshold, will drive formation of transition state
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(can go in either direction!)
Probability of spontaneously acquiring this energy allows
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calculation of rate constant
Signaling pathways are DYNAMIC and in EQUILIBRIUM
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The energy of a molecule fluctuates!
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Enzymes catalyze reactions by lowering the free energy
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of transition states
Releasing Free Energy is not Always “Easy”
Capture energy in glucose to drive ATP formation!
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Glucose (chemical E) →CO2+ H2O ( G < 0)
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Can then use this energy via ATP hydrolysis
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ADP + Pi→ATP ( G > 0)
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Organisms burn ATP to drive unfavorable reactions
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Cells capture free energy in ATP
Creates an overall negative delta G
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Coupling: using energetically favorable reactions to drive energetically unfavourable
reactions
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Lecture 1: Introduction to Energy
January 12, 2018
5:44 AM
Section 1 Page 1
Document Summary
Animals do not consume energy! (first law of thermodynamics!) Living things convert energy from one form to another, but never created or destroyed! Plants take energy from photon, convert to chemical energy through ps. You can store chemical energy in the form of more biomass. Number 2: organisms store energy temporarily during activity. Conversions of chemical bonds into heat and work. We"re converting a simple molecule into a complex organism. Seems to go against 2nd law of thermodynamics that disorder and entropy are always increasing in the universe! Joule showed that increase in water temperature (thermal e) was directly related to height of mass spinning paddles from pulley. Potential e of mass on pulley is very high quality energy, has high amount of order. Energy in water tank low quality, due to random motion of molecules. Consume high quality energy (food, chemical bonds) and convert it into low quality energy (heat and work)
