1. Energy is life

2. Thermodynamics Thermal Energy – 2 parts
1) chemical energy stored in bonds of molecules
2) kinetic energy of Brownian motion
Temperature = average kinetic energy of molecules
Heat = flow of KE from one object/place to another

3. Metabolism = all biological chm rxn
Metabolic pathways = a series of chm rxn resulting in a set product….
each step catalyzed by different enzyme
Catabolism = energy releasing pathways
( degradative )
Anabolism = pathways that consume energy to build complex molecules
(biosynthetic)

4. Laws of Thermodynamics
1st law – conservation of energy….
energy not created or destroyed only converted one form to another
2nd law – All systems tend to entropy (chaos) (disorder)
unless energy is being put in
transforming energy results in loss of organized, usable energy as heat

5. 1865 Philosophical Society of Zurich presentation Clausius concludes:
‘The entropy of the universe tends to a maximum.’
This statement is the best-known phrasing of the second law. Because of the looseness of its language, and lack of specific conditions, e.g. open, closed, or isolated, many people take this simple statement to mean that the second law of thermodynamics applies virtually to every subject imaginable. This, of course, is not true; this statement is only a simplified version of a more extended and precise description.

6. 2nd law - 1854, the Clausius statement:
Heat can never pass from a colder to a warmer body without some other change, connected therewith, occurring at the same time
Biological version – enzyme mediated chemical reactions cause the change that decreases the entropy of a substance
spontaneous processes occur on their own to increase disorder
Heat flows from high concentration of heat to low
Molecules flow from high concentration to low
Diffusion spreads molecules out increasing entropy

7. 1st & 2nd law bio-style 1) The universe tends toward chaos (entropy)
2) Without the input of E. disorder increases
…dead things decompose
3) Solar E. is added to ecosystems via
photosynthesis
4) Conversion of E from one form to another results in loss of usable energy in form of heat
Thus limiting length of food chain…only
10% of energy taken in is passed up chain

8. Gibbs free energy …G Free energy (G) can perform work
ΔG indicates if a reaction will be spontaneous

9. Negative ΔG increases entropy = spontaneous
(new molecules are lower E… degradative)
exergonic pathway

10. Positive ΔG decreases entropy = require an input of energy to occur (synthesizes molecules that are higher E)
endergonic pathway

11. ΔG = ΔH - T ΔS
ΔH = change in enthalpy
ΔS = change in entropy
T = absolute Temperature in Kelvin
ΔG = change in Gibbs free energy

12. Metabolism Exergonic Cellular respiration Endergonic Photosynthesis
Catabolism
Anabolism
Degredative
Breaks down large mol.
Hydrolysis rxns
Increases entropy by
Releasing E. (- ΔG)
Exergonic
Cellular respiration
Biosynthetic
Builds large molecules
Condensation rxns
Decreases entropy by
Storing E in mol. (+ ΔG)
Endergonic
Photosynthesis

13. Energy Coupling Exergonic rxns power endergoninc rxns
Energy is transferred via ATP

14. Adenosine triphosphate
Nucleoside used in RNA (ribose + adenine)
Plus 3 phosphates
Hydrolysis of ATP releases…
inorganic phosphate (Pi)+ 13 kcal/mol
Proteins can harness that E to …
1) transport molecules (protein pumps)
2) move things ( motor proteins)
3) drive endergonic rxns

15. ATP drives endergonic rxns by..
Substrate level phosphorylation :
enzyme transfers one Phosphate from ATP to a molecule creating an
Unstable intermediate(phosphorylated intermediate)
Unstable intermediate is a higher energy mol.
more likely to react spontaneously…releasing the Pi

16. Glu + NH3= endergonic (+G)
So in body Glu forms an unstable phosphorylated intermediate first
Then the Pi is replaced
by the lower energy NH3
Combined the reactions
are exergonic (-G)
& therefore spontaneous

17. ATP moves proteins by 1) ATP is hydrolyzed and protein is
phosphorylated…then Pi is released result:
protein changes its structure

18. 2) ATP binds to protein ...hydrolyzing ATP releases energy that causes protein to change shape

21. Enzymes 1) Proteins (except… ribozymes RNA enzymes)
2)Biological catalysts
3) Speed reactions but are NOT
a reactant (not used up)
4) lower activation energy
5) do NOT alter overall ΔG

24. Enzyme Vocab…. Substrate = reactant enzyme binds Active site =
pocket where substrate fits into enzyme
Induced fit = alteration of substrate or active site
to make a better fit between them

25. Allosteric site =
pocket other than active site where
activators & inhibitors can bind

26. Activators = increase the activity of enzyme
… stabilize enzyme in active form
Inhibitors = block activity of enzyme
…stabilize enzyme in inactive form

27. Activation Energy lowered by…
1) aligning molecules favorably
2) putting stress on bonds in molecule
3)creating favorable
microenvironment

28. Allosteric Regulation
Allosteric regulator molecules all bind to allosteric site
activator molecules stabilize enzyme in active form
inhibitor molecules
stabilize enzyme
in inactive form

29. Specificity of Active Sites
1) Based on shape, size, pH, polarity, charge
2) Substrate held in place by weak interactions
(H-bonds, ionic bonds)
3) Enzymes only catalyze one reaction
4) May be reversible (depends on concentrations)
5) Competitive inhibitors mimic substrate, bind active site covalently & inactivate enzyme….
can be overcome by vast in substrate conc.

31. Feed-Back Inhibition (allosteric)
The end-product of a pathway shuts down the first enzyme of the pathway that creates it
Prevents
overproduction
of products

32. Cofactors Non-protein molecules/atoms needed for enzymes to work
Inorganic cofactors include Zn Fe & Cu ions
Organic cofactors are called coenzymes
include many vitamins & vitamin derivatives
and nucleotides like NAD+ & FAD

33. Things that influence reaction rates..
Concentration of enzymes/coenzymes/cofactors pH
Temperature
Concentration of substrate
Concentration of allosteric molecules
Localization of reactions (compartmentalization)
Denatured enzymes or altered enzyme structure

35. Ph effect on enzymes
Optimum pH
Acidic (lowpH) Basic (highpH)

36. Temperature Increasing temperature Increases KE
Increases reaction rate
Excessive Temperature denatures enzyme by
Breaking H bonds that
Hold enzyme in its secondary structure

37. Do Scientific Skills Exercise p128
Please read the information and do #1 and #4