ATP and Enzymes Flashcards
Metabolism
The totality of an organism’s chemical reactions
Free Energy ΔG
The portion of a system’s energy that can do work when pressure and temperature are uniform, as in a living cell
Free energy is also a measure of a system’s instability: the more free energy a system has, the less stable it is
Endergonic
Absorbs free energy from its surroundings. Because free energy is stored, ΔG is positive and Endergonic reactions are not spontaneous.
Ex: Energy for cellular work.
Exergonic
A spontaneous reaction with a net release of free energy. ΔG is negative.
Ex: Cellular Respiration/ATP Synthesis ATP hydrolysis
Activation Energy (Ea)
The minimum energy required for a specific reaction to occur.
Ea allows the cell to control when chemical reactions occur
Enzyme
Enzymes lower the Activation Energy barrier, speeding up the process of the reaction. They also do not get used up in the process.
Enzymes have structural specificity for their substrates
Ex: Without sucrase, sucrose would sit in water for years without being broken down by hydrolysis.
ATP Hydrolysis
Hydrolysis adds water to break off the gamma phosphate in ATP, releasing so much energy. The gamma phosphate turns into an inorganic phosphate.
Ex: The hydrolysis of ATP produces much more energy than the hydrolysis of other molecules due to the instability of the triphosphate group. Once ATP becomes ADP, energy is released. This powers many metabolic reactions in a cell.
Thermophiles
microorganisms with optimal growth temperatures between 60 and 108 degrees CELSIUS isolated from marine and terrestrial geothermally heated habitats
Non-competitive Inhibitor
These types of inhibitors bind to a different region of the enzyme than the active site which changes the shape of it and deters its function.
Ex: The poison cyanide binds to and
blocks the function of cytochrome oxidase – a
carrier molecule that forms part of the electron
transport chain.
Competitive Inhibitor
These reduce the productivity of enzymes by blocking the active site. This can be overcome by increasing the concentration of substrate.
Ex: Penicillin blocks the active site
of an enzyme necessary for the synthesis of
peptidoglycans which many bacteria use to make
their cell wall.
Bioenergetics
the study of how energy
flows through living organisms
What kind of work does a cell need to perform?
- Chemical Work: ATP phosphorylates key reactants
- Transport Work: ATP Phosphorylates transport proteins
- Mechanical Work: ATP binds noncovalently to motor proteins and then is hydrolyzed
Energy for work comes from chemical reactions
Chemical Work example includes a phosphorylated intermediate of glutamic acid by ATP driving an endergonic reaction.
Energy Coupling
ATP mediates most energy coupling in cells and provides an immediate source of energy to power cellular work
ATPase
Enzymes that catalyze the hydrolysis of ATP into ADP
How does a phosphorylated intermediate make an endergonic reaction energetically favorable?
Energy released by ATP hydrolysis can be directly used to drive chemical reactions
