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The first Law of Thermodynamics
- Energy cannot be created or destroyed, it can only be converted from one form to another.
- generally lose as heat
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The Second law of thermodynamics
- all systems tend to become more disorganized
- increased entropy
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Biological reaction tent to occur if
- they release heat
- lead to disorder
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Spontaneous Rxn
when products are favored over the reactants
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Gibbs free energy
- a function that determines the spontaneity of a reaction
- G cannot be measured directly (only ∆G)
- if ∆ G is negative the reaction is spontaneous
- if ∆G is zero, the reaction is at equilibrium
- if ∆G is positive the reaction is non-spontaneous
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∆G = ∆H - T∆S
- ∆G = the difference in Gibbs free energy
- ∆H = the difference in enthalpy
- T = the absolute temperature in K
- ∆S = the change in entropy of the universe
- guppies are hell without tartar sauce
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A reaction can be spontaneous if
- it is exothermic (-∆H) and leads to disorder (+∆S)
- it is really exothermic, and leads to increased order (-∆S)
- It is endothermic, but leads to a lot of disorder (+∆S)
- It itself is non-spontaneous but is coupled to a spontaneous one
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∆G
- describes the free energy change under any specified condtions
- must know [Reactants] and other aspects of subcellular conditions (difficult to find)
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∆G˚
- describes the free energy change under standard condtions:
- temp @ 25˚C
- pressure @ 1 atmosphere
- solutes at 1 M (except water) (pH = 0)
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∆G˚'
- is the free energy change under standard conditions at pH 7
- = -2.303 RT log([P]/[R])
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ATP Hydrolysis
- ATP + H2O = ADP + Pi + H+
- super high ∆G˚' = -30.5kJ/mol
- very spontaneous
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e.g. of coupled rxn
- glucose-6-phosphate = fructose-6-phosphate
- - ∆G˚' = +1.7 kJ/mol
- fructose-6-phosphate = fructose-1,6-bisphosphate + ADP
- - ∆G˚' = -14.2 kJ/mol
- therefore over all ∆G˚' = -12.5 kJ/mol
- ie coupling with ATP makes it favorable
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catabolism
- breakdown of large molecules to smaller ones
- streat to glucose to carbon dioxide
- releases
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Anabolism
- synthesis of large molecules from smaller ones
- carbon dioxide to glucose to starch
- requires input of energy
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OIL RIG
- oxidation is the loss of electrons
- reduction is the gain of electrons
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Oxidation Reduction (redox)
- Transfer of e-
- have an associated ∆G
- this energy can be used in metabolism
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Reductant
the more reduced compound is oxidized
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oxidant
the more oxidized compound is reduced
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- NAD+ NADP+
- nicotinamide adenine dinucleotide / phosphate
- catobolic processes
- oxidized gets 2e- in hydroxide
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Oxidized form of NAD/NADP
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- FAD (reduced from FADH2)
- FMN (reduced from (FMNH2)
- co-enzyme
- electron carrier
- accepts one e- at a time
- up to 2
- cycle between oxidized and reduced forms
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- ATP
- need 30.5 kJ/mol of energy for syntheses
- Not for energy storage (glycogen, fat, sucrose, startch)
- can be rapidly resynthesized
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glycolysis provides substrates for:
- citric acid cycle
- anaerobic glycolysis
- alcoholic fermentation
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glycolysis uses in a general sence
- glucose
- ADP
- Pi (inorganic P)
- NAD+
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glycolysis produces in a general sense
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- Product: glucose-6-phosphate + ADP + H+
- enzyme: hexokinase
- Co-factor: ATP
- Arrow: ->
- Type of rxn: phosphory group transfer
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- Product: fructose-6-phospahte
- enzyme: phosphoglucose isomerase
- Co-factor: none
- Arrow: <->
- Type of rxn: Isomeration-rearrangment
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- Product: fructose-1,6-bisphoshate + ADP + H+
- enzyme: phosphofructokinase
- Co-factor: ATP
- Arrow: ->
- Type of rxn: phosphoryl group transfer
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- Product: dihydroxyacetone phosphate and glyceraldehye-3-phospate
- enzyme: aldolase
- Co-factor: None
- Arrow: <->
- Type of rxn: nonhydrolytic cleavage rxn
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- Product: glyceraldehyde-3-phospate
- enzyme: triosephosphate isomerase
- Co-factor: None
- Arrow: <->
- Type of rxn: Isomerization-rearrangement
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- Product: 1,3-bisphosphoglycerate + NADH + H+
- enzyme: glyceraldehyde-3-phospate dehydrogenase
- Co-factor: NAD+ + Pi
- Arrow: <->
- Type of rxn: Oxidation reduction, phosphoryl group trasphate
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- Product: 3-phosphoglycerate + ATP
- enzyme: phosphoglycerate kinase
- Co-factor: ADP
- Arrow: <->
- Type of rxn: substrate level phophorylation
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- Product: 2-phosphoglycerate
- enzyme: phosphoglycerate mutase
- Co-factor: None
- Arrow: <->
- Type of rxn: Isomerization-rearrangement
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- Product: phosphoenolpyruvate (PEP) + H2O
- enzyme: enolase
- Co-factor: None
- Arrow: <->
- Type of rxn: non hydrolytic cleavage
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- Product: pryrvate + ATP
- enzyme: Pyruvate kinase
- Co-factor: ADP + H+
- Arrow: ->
- Type of rxn: substrate level phosphorylation
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∆G˚' for glycolysis
-73.3 kJ/mol
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Glycolysis net equation
- glucose + 2NAD+ + 2Pi + 2ADP ->
- 2 pyruvate + 2ATP + 2NADH + 2H+
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Why do you need NAD+ for glycolysis
it is a place for the e- to go
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Without O2
ATP is produced directly from glycolysis
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How is NAD+ regenerated in anaerobic situations in yeast and mammals?
Step 1:
- Products: NAD+ and Lactate
- then transported to liver where gluconeogensis happens
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How are the irreversible reactions of glycolysis overcome in gluconeogenesis?
- has four new steps
- doesn't use: hexokinase, phophofructokinase, or pyruvate
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Step 1 of Gluconeogenesis
- Enzyme: pyruvate carboxylase
- Makes: ADP, P and 2H
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Step 2 Glucosgenesis
+ GTP
- Enzyme: phosphoenolpyruvate carboxykinase
- Makes: GDP + CO2 +
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Step 9 of Gluconeogenesis:
+ H 2O
- Enzyme: Fructose-1,6-bisphosphatase
- Makes: Pi +
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Step 11 of Geucoeogenesis
+ H 2O
- Enzyme: glucose-6-phospatase
- Makes: Pi +
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What are the key energy producing steps in glycolysis?
- Step 7 with phosphoglycerate kinase
- Step 10 with pyruvate kinase
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