Chapter 15- Metabolism Flashcards
What is metabolism?
What is anabolism and catabolism?
Metabolism- all enzyme catalyze reactions collectively (turned off and on as needed)
Gets chemical energy from degrading nutrients
Convert nutrients into building blocks of macromolecules
Assemble building blocks into macromolecules-proteins, nucleic acids, lipids, polysaccharides
Form and degrade biomolecules
It is the sum of anabolism (small molecule converted to larger complex molecules, combust carbon fuels to synthesize atp) and catabolism (breakdown of larger organic nutrient molecules to smaller simpler molecules, use atp to synthesize large biomolecules)
What are the 5 basic principle that govern energy manipulations in all cells?
- Molecules degraded or made step wise in metabolic pathways (can be linear branched or circular)
- ATP is energy currency
- ATP is firmed from oxidation of carbon fuels
- Few reaction types that contain intermediates common to all metabolic pathways
- Metabolic pathways are highly regulated
What are the intermediates in metabolic pathways?
Metabolites
What are the two necessary things in order to construct a metabolic pathway?
- The individual reaction must be specific
- The pathway in total must be thermodynamically favourable
(Thermodynamically unfavourable reaction can be driven by coupling to a more favourable reaction)
What are the two thermodynamic laws?
First law: total amount of energy in the universe remains constant
Second law: the amount of entropy (total disorder) in the environment increases as a result of all chemical and physical changes
What is free energy (G)?
What does it mean to be exergonic or endergonic?
Free energy performs useful work at constant temperature and pressure (every reaction causes a change in free energy)
Exergonic- ΔG is negative, initial state energy level of reactants is higher than final product
Endergonic- ΔG is positive, initial states energy level or reactants is lower than final product
Will not move in forward direction unless input energy is added
What is heat energy (H)?
What is entropy (S)
What equation links free energy, heat energy, and entropy?
Heat energy- total heat content of a system (enthalpy) occurs through a change of temp and pressure
Entropy- energy state of randomness and disorder (useless energy)
ΔG=ΔH-TΔS
What is the equation for standard free energy (at 1M, 1atm, and pH 7.0)?
What are the three Keq’s (1, <1, >1) and what do they mean for G?
ΔG’=-RT ln(Keq)
Or
ΔG’=-2.3RT log(Keq)
Keq= 1, ΔG*’= 0 (reaction at equilibrium) Keq= <1, ΔG*’= positive, does not favour forward reaction only reverse (reaction doesn’t proceed) Keq= >1, ΔG*’= negative, favours forward reaction (spontaneous)
How do you calculate actual free energy? (ΔG)
A+B C+D
ΔG=ΔG* + RT ln[CD/AB]
ABCD are concentrations
At equilibrium ΔG=0 so ΔG*= -RT ln [CD/AB]
Keq= ([C][D]/[A][B])
Slide 19-20
What are the 3 key factors that make ATP have a high phosphoryl transfer potential?
- Charge repulsion (4 negative repulse)
- Resonance stabilization
- Stabilization by hydration
ATP is energy currency because it has stable bonds that want to break and ADP and P (the products of ATP) are stable
Slide 22
What is oxidation and reduction reactions?
What is the reduction potential?
Oxidation- loss of electrons (sometimes also protons)
Reduction- gain of electrons (sometimes also protons)
Reduction potential (E)- measures affinity for electrons in Volta
Standard reduction potential (E)
Standard reduction potential at pH 7 (E’)
Electrons move from lower E to higher E
Slide 26
Look at the structures of NAD+ and FAD on slides 29-31
Okay
How do you find the standard free energy at pH 7 with number of electrons?
ΔG’=-nFE’net
n is number of electrons
F is faradays constant
E*’net is net reduction potential
Slides 33-35
How do you find The net reduction potential at pH 7? (E*’net)
E’net= E’ (for reduction reaction)-E*’ (for oxidation reaction)
Slides 33-35
How much ATP is produced when you oxidize NADH?
2.5 ATP
