대사과정: 생체고분자의 합성과 분해, 에너지 대사

자동차에 비유하면

자동차의 부속품: 고분자 생화학, 단백질 생화학

자동차의 작동원리: 대사 생화학

자동차의 설계도: DNA

1. overview of metabolism

same metabolic principles: common evolutionary origin and the constraints of the laws of thermodynamics

A. Trophic strategies

nutritional requirements reflect its source of metabolic free energy

autotrophs: chemolithotrophs, photoautotrophs

heterotrophs

oxidizing agents for nutrient breakdown

aerobes

anaerobes

B. metabolic pathways

series of connected enzymatic reactions that produce specific products

        metabolites

        energy

        reducing power

metabolic pathways occur in specific cellular locations

C. thermodynamic considerations

metabolic flux:

        near-equilibrium: easily reversible, quickly restore equilibrium, regulated by the relative concentrations of substrates

        far-equilibrium: irreversible, controlled by enzymatic activity

        different pathways for catabolism and anabolism

D. Control of metabolic flux

equilibrium & steady state

at equilibrium, no flux

at steady state, constant flux determined by the rate-determining step

several mechanisms to control the rds

        allosteric control: rapid

        covalent modification

        substrate cycle: rapid

        genetic control

2. High-energy compounds

the energy released by oxidation is conserved by the synthesis of a few types of "high-energy intermediates" to pay for the E-requiring processes

A. ATP and phosphoryl group transfer

phosphoryl group transfer potentials

the energy in high-energy compounds

        resonance unstability

        electrostatic repulsion

        lower solubility

B. coupled reactions

        ATP synthesis

        ATP hydrolysis

        NTPs

C. Other phosphorylated compounds

D. Thioesters

    primitive high energy compound (phosphate is scarce)

    Coenzyme A: acetyl-CoA, acyl-CoA

3. oxidation-reduction reactions

    A. NAD+ and FAD

        O2 receive one electron at a time

    B. the Nernst equation

        half reactions (redox couples)