BCH 3120 Study Guide - Winter 2018, Comprehensive Midterm Notes - Thiolase, Small Intestine, Skeletal Muscle
12 Oct 2018
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BCH 3120
MIDTERM EXAM
STUDY GUIDE
Fall 2018
What is metabolism?
• The sum of biochemical processes involved in the synthesis (anabolism),
breakdown (catabolism), and inter-conversion of constituents in cells and
organisms
Intermediary metabolism
Metabolic pathways
• Series of enzymatic reactions leading to a products (metabolites)
• Main metabolic pathways:
o Carbohydrates metabolism
o Lipids metabolism
o Amino acid metabolism
o Nucleic acid metabolism
Characteristics of metabolic pathways
• Irreversible
• Anabolism and catabolism use different pathways
o Depending on energy demand
o Allows an independent control
• Each pathway has a committed step (irreversible reaction)
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• All pathways are regulated
• Metabolic pathways take places in specific intracellular sites.
o Intracellular compartmentalization but also at the level of the organs
and tissues.
Fundamental concepts of metabolism
Bioenergetics
• In order to keep our system, cell, organ, body in a steady state, we need:
o Building blocks (nutrients, food),
o Workers (enzymes and cofactors) and
o Traffic control (compartmentalization, thermodynamics and
enzymatic control)
• Importantly, all this work is made possible by using the energy in the
nutrients to transform and use it for other purposes. This need for energy is
constant.
Energy is provided by electron flow
• Virtually all energy transductions in cells can be traced to this flow of
electrons, from one molecule to another, in a downhill flow from higher to
lower electrochemical potential.
• Oxidation-reduction reactions
o Where one reactant is oxidized (loses electrons) an another is
reduced (gains electrons)
Regulation and control of metabolic pathways
• To maintain a dynamic steady state and in order to use its available
resources efficiently, organisms heavily control how these resources are
used.
• Control measures:
o Thermodynamics
o Cell-cell communication and compartmentalization
o Inhibition and allosteric control
o Post-translational modifications
o Enzyme turnover
Control measures: Thermodynamics
Free Gibbs energy
• ΔG = ΔH- TΔS
• The change in randomness of a reaction or system is expressed as the
difference in entropy ΔS
• The number and kinds of bonds involved in the reaction in the measure of
enthalpy Δ(
• The measure of total free energy capable of doing work for a reaction at
constant temperature and pressure is termed the Gibbs free energy ΔG
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Document Summary
What is metabolism: the sum of biochemical processes involved in the synthesis (anabolism), breakdown (catabolism), and inter-conversion of constituents in cells and organisms. Metabolic pathways: series of enzymatic reactions leading to a products (metabolites, main metabolic pathways, carbohydrates metabolism, lipids metabolism, amino acid metabolism, nucleic acid metabolism. In order to keep our system, cell, organ, body in a steady state, we need: building blocks (nutrients, food), workers (enzymes and cofactors) and, traffic control (compartmentalization, thermodynamics and enzymatic control) Importantly, all this work is made possible by using the energy in the nutrients to transform and use it for other purposes. If the sum of the free energy change is still negative (- g(cid:524), the reactions are favourable and the exergonic reaction will force the endergonic ones. Standard free energy change (cid:523)dg "(cid:524) change (dg): standard free energy change (dgo(cid:495)(cid:524) is different from actual free energy, the standard free energy change (dgo(cid:495)(cid:524) is a constant .
