10/16/24, 11:10 Chapter 3 - Energy, Catalysis, and
AM Biosynthesis
Chapter 3: Energy, Catalysis, and Biosynthesis
Contents
- Use of energy by cells
- Free energy and catalysis
- Activated carriers and biosynthesis
Catabolic and Anabolic Pathways
- Catabolic and anabolic pathways together constitute the cell’s metabolism
- During catabolism, a major portion of the energy stored in the chemical bonds of food
molecules is dissipated as heat
- Some of this energy is converted to the useful forms of energy needed to drive the synthesis of
new molecules in anabolic pathways, as indicated
- Catabolic: from larger molecules smaller (preferred due to entropy)
- Anabolic pathways: smaller building blocks macromolecules (requires a lot more energy)
o Measure this using Gibbs free energy
- (image)
The Use of Energy By Cells
- Cells can convert energy from one form to another
- Different forms of energy are interconvertible, but the total amount of energy must be converted
- The large amount of chemical-bond energy released when water (H2O) is formed from H2
and O2 is initially converted to very rapid thermal motions in the two new H2O molecules;
however, collisions with other H2O molecules almost instantaneously spread this kinetic
energy evenly throughout the surroundings (heat transfer), making the new H2O molecules
indistinguishable from all the rest. Cells can convert chemical-bond energy into kinetic
energy to drive, for example, molecular motor proteins; however, this occurs without the
intermediate conversion…
- (image)
- Oxidation and reduction involve electron transfers
- Oxidation and reduction involve a shift in the balance of electrons
- A) When two atoms from a polar covalent bond, the atom that ends up with a greater share of
electrons is said to be reduced, while the other atom, with a lesser share of electrons, is said to
be oxidized. Electrons are attracted to the atom what has a greater electronegativity. As a
result, the reduced atom requires a partial negative charge; conversely, the oxidized atom
acquires a partial positive charge, as the positive charge on the atomic nucleus now exceeds
the total charge of the electrons surrounding it.
- LEO says GER or OIL RIG
- Can count the number of C-H bonds; if number reduced oxidation; adding C-H bonds
reduction
- (image)
Free Energy and Catalysis
- Enzymes reduce the energy needed to initiate spontaneous reactions
- Activation energy required
- Enzymes reduce activation energy for catalyzed reaction
- Substrate binds to enzyme to create substrate-enzyme complex catalysis enzyme-product
complex release of product enzyme with an open active site to cycle back to substrate
binding
- Free energy (G) change (∆G) for a reaction determines whether it can occur
- ∆G as a reaction proceeds toward equilibrium
- If negative reaction spontaneous
- The free energy of Y is greater than the free energy of X. Therefore, ∆G is negative, and
the disorder of universe increases when Y is converted to X. This reaction occurs
spontaneously.
about:blan 1/
k 2
AM Biosynthesis
Chapter 3: Energy, Catalysis, and Biosynthesis
Contents
- Use of energy by cells
- Free energy and catalysis
- Activated carriers and biosynthesis
Catabolic and Anabolic Pathways
- Catabolic and anabolic pathways together constitute the cell’s metabolism
- During catabolism, a major portion of the energy stored in the chemical bonds of food
molecules is dissipated as heat
- Some of this energy is converted to the useful forms of energy needed to drive the synthesis of
new molecules in anabolic pathways, as indicated
- Catabolic: from larger molecules smaller (preferred due to entropy)
- Anabolic pathways: smaller building blocks macromolecules (requires a lot more energy)
o Measure this using Gibbs free energy
- (image)
The Use of Energy By Cells
- Cells can convert energy from one form to another
- Different forms of energy are interconvertible, but the total amount of energy must be converted
- The large amount of chemical-bond energy released when water (H2O) is formed from H2
and O2 is initially converted to very rapid thermal motions in the two new H2O molecules;
however, collisions with other H2O molecules almost instantaneously spread this kinetic
energy evenly throughout the surroundings (heat transfer), making the new H2O molecules
indistinguishable from all the rest. Cells can convert chemical-bond energy into kinetic
energy to drive, for example, molecular motor proteins; however, this occurs without the
intermediate conversion…
- (image)
- Oxidation and reduction involve electron transfers
- Oxidation and reduction involve a shift in the balance of electrons
- A) When two atoms from a polar covalent bond, the atom that ends up with a greater share of
electrons is said to be reduced, while the other atom, with a lesser share of electrons, is said to
be oxidized. Electrons are attracted to the atom what has a greater electronegativity. As a
result, the reduced atom requires a partial negative charge; conversely, the oxidized atom
acquires a partial positive charge, as the positive charge on the atomic nucleus now exceeds
the total charge of the electrons surrounding it.
- LEO says GER or OIL RIG
- Can count the number of C-H bonds; if number reduced oxidation; adding C-H bonds
reduction
- (image)
Free Energy and Catalysis
- Enzymes reduce the energy needed to initiate spontaneous reactions
- Activation energy required
- Enzymes reduce activation energy for catalyzed reaction
- Substrate binds to enzyme to create substrate-enzyme complex catalysis enzyme-product
complex release of product enzyme with an open active site to cycle back to substrate
binding
- Free energy (G) change (∆G) for a reaction determines whether it can occur
- ∆G as a reaction proceeds toward equilibrium
- If negative reaction spontaneous
- The free energy of Y is greater than the free energy of X. Therefore, ∆G is negative, and
the disorder of universe increases when Y is converted to X. This reaction occurs
spontaneously.
about:blan 1/
k 2
