CHE 350 Lecture Notes - Lecture 6: Centriole, Rate-Determining Step, Thermodynamics
Chapter 14 – Introduction to Metabolism
Metabolism = the overall process through which living systems acquire and use free energy to
carry out their various functions. 2 types = catabolism and anabolism
Catabolism = degradation; in which nutrients and cell constituents are broken down to
salvage their components and/or to make energy available
oCarry out the exergonic oxidation of nutrient molecules. The free energy released
is used to drive endergonic processes like anabolic rxns, mechanical work, and
active transport of molecules against concentration gradients
Anabolism = biosynthesis; in which biomolecules are synthesized from simpler
components
1 | Overview of Metabolism
A – Nutrition Involves Food Intake and Use
Nutrition = intake and utilization of food
The nutritional requirements of an organism reflects its source of metabolic energy
oAutotrophs = synthesize all their cellular constituents from simple molecules
(H2O, CO2, NH3, H2S)
Chemolithotrophs = obtain energy thru oxidation of inorganic compounds
(NH3, H2S, even Fe2+)
Photoautotrophs = energy via photosynthesis (light transfers energy from
inorganic donors to CO2 carbs later oxidized to release free energy)
oHeterotrophs = obtain free energy thru oxidation of organic compounds (carbs,
lipids, proteins) and ultimately depend on autotrophs for them
Organisms can further be classified by the identity of the oxidizing agent for nutrient
breakdown
oObligate aerobes (ex: animals) = use O2
oAnaerobes = sulfate or nitrate
oFacultative anaerobes = grow in presence of absence of O2
oObligate anaerobes = poisoned by O2
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B – Vitamins and Minerals Assist Metabolic Rxns
Vitamins = can’t synthesize it, from diet only
o2 classes = Water soluble and fat soluble
Most water-soluble vitamins are converted to coenzymes
oNicotinamide + Nicotinic acid = form the redox-active components of the
nicotinamide coenzymes NAD+ and NADP+ deficiency = pellagra
oThe water-soluble vitamins in the human diet are all coenzyme precursors
vs fat-soluble vitamins, which aren’t (except for Vitamin K)
C – Metabolic Pathways Consist of Series of Enzymatic Rxns
Metabolic pathways are series’ of connected enzymatic rxns that = specific products
Metabolites = their reactants, intermediates, and products
Degradative and biosynthetic pathways are related in this way:
oIn degradative pathways, the major nutrients (complex metabolites) are
exergonically broken down into simpler products.
oThe free energy released in this degradative process is conserved by the synthesis
of ATP from ADP + P, or by the reduction of a coenzyme like NADP+ to
NADPH
oATP and NADPH are the major free energy sources for biosynthetic reactions
oWhat degradative pathways create, biosynthetic pathways use
The pathways for the catabolism of a large number of diverse substances (carbs, lipids,
proteins) converge on a few common intermediates (ex: acetyl-CoA)
oThese intermediates are then further metabolized in a central oxidative pathway,
citric acid cycle, electron transport train
Biosynthetic pathways carry out the opposite process – relatively few metabolites serve
as starting materials for a host of varied products
find more resources at oneclass.com
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Document Summary
Metabolism = the overall process through which living systems acquire and use free energy to carry out their various functions. Catabolism = degradation; in which nutrients and cell constituents are broken down to salvage their components and/or to make energy available: carry out the exergonic oxidation of nutrient molecules. The free energy released is used to drive endergonic processes like anabolic rxns, mechanical work, and active transport of molecules against concentration gradients. Anabolism = biosynthesis; in which biomolecules are synthesized from simpler components. A nutrition involves food intake and use. Nutrition = intake and utilization of food. The nutritional requirements of an organism reflects its source of metabolic energy: autotrophs = synthesize all their cellular constituents from simple molecules (h2o, co2, nh3, h2s) Chemolithotrophs = obtain energy thru oxidation of inorganic compounds (nh3, h2s, even fe2+) B vitamins and minerals assist metabolic rxns. Vitamins = can"t synthesize it, from diet only: 2 classes = water soluble and fat soluble.
