Please enable JavaScript.
Coggle requires JavaScript to display documents.
An introduction to metabolism (An organism's metabolism transforms…
An introduction to metabolism
An organism's
metabolism
transforms
matter
and
energy
, subject to the laws of
thermodynamics
.
Bioenergetics
: The study of how energy flows through living organisms.
Forms of Energy
.
Heat
: is when thermal energy transfers from one object to another.
Potential Energy
: An object that is not presently moving still containing energy.
Thermal Energy
: is kinetic energy associated with the random movement of atoms or molecules.
Chemical Energy
: a term used by biologist to refer to potential energy available for release in a chemical reaction.
Kinetic Energy
: associated with the relative motion of objects.
The laws of Energy Transformation
.
First Law
: The energy of the universe is constant; Energy can be transferred and transformed, but it cannot be created or destroyed.
Thermodynamics
: The study of energy transformations that occur in a collection of matter.
Second Law
: Every Energy transfer or transformation increases the entropy of the universe.
Entropy
: is a measure of molecular disorder, or randomness. The more randomly a collection of matter is the greater the entropy.
Free Energy and Metabolism.
Free Energy
: is the portion of a system's energy that can perform work when
temperature
and
pressure
are uniform throughout the system, as in a living cell.
The free energy change of a reaction tells us whether or not the reaction occurs spontaneously.
Spontaneous process
: A process that on it's own leads to an increase to entropy without the input of energy.
Nonspontaneous
: is a process that on it's own leads to a decrease to entropy.
ΔGº = ΔHº – TΔS
: is the maximum amount of non-expansion work that can be extracted from a thermodynamically closed system
closed system
: is a physical system that does not allow certain types of transfers (such as transfer of mass and energy transfer) in or out of the system.
The relationship of free energy to
stability
,
work capacity
, and
spontaneous change
.
Gravitational motion
: Objects move spontaneously from a higher altitude to a lower one.
Diffusion
: Molecules in a drop of dye diffuse until they are randomly dispersed.
Chemical reaction
: in a cell, a glucose molecule is broken down into a simpler molecules.
ATP powers cellular work by coupling exergonic reactions to endergonic reactions.
Exergonic and Endergonic Reactions in Metabolism.
Endergonic reaction
: is one that absorbs free energy from its surrounding. Thus since energy is stored reaction is non spontaneous.
Exergonic reaction
: proceeds with a net release of free energy. Because the chemical mixture loses free energy, ΔG is negative for an exergonic reaction making it spontaneous.
Energy Coupling
: the use of an exergonic process to drive an endergonic one.
A cell does three main kinds of work:
Chemical work
: the pushing of endergonic reactions that would not occur spontaneously, such as the synthesis of polymers from monomers.
Transport work
: the pumping of substances across membranes against the direction of spontaneous movement.
Mechanical work
: the contraction of muscle cells, and the movement of chromosomes during cellular reproduction. Example the beating of cilia.
Cellular Respiration and Fermentation
Catabolic pathways and production of ATP
Catabolic pathways
yield energy by oxidizing organic fuels.
Energy flows into an ecosystem as
sunlight
and ultimately leaves a
heat
, while the
chemical elements
essential to life are recycled.
Fermentation
: is a partial degradation of sugars or other organic fuel that occurs without the use of oxygen.
Aerobic respiration
: the most efficient catabolic pathway. It is when oxygen is consumed as a reactant along with the organic fuel.
Cellular respiration
: includes both aerobic and anaerobic processes.
The Principle of Redox.
The relocation of electrons releases energy stored in organic molecules, and this energy ultimately is used to synthesize ATP.
In many chemical reactions, there is a transfer of one or more electrons from one reactant to another.
Redox reactions
: Electron transfers that are called oxidation-reduction reactions.
Oxidation
: the loss of electrons from one substance.
Reduction
: the addition of electrons to another substance.
Reducing agent
: is an element or compound that loses (or "donates") an electron to another chemical species in a redox chemical reaction. Since the reducing agent is losing electrons, it is said to have been oxidized.
Oxidizing agent
:is a chemical species that removes an electron from another species. It is one component in an oxidation-reduction (
redox
) reaction. In the second sense, an oxidizing agent or an oxidizer is a chemical species that transfers electronegative atoms, usually oxygen, to a substrate.
The Stages of Cellular Respiration
Glycolysis
:is the metabolic pathway that converts glucose C6H12O6, into pyruvate, CH3COCOO + H. The free energy released in this process is used to form the high-energy compounds ATP
Glycolysis
harvests chemical energy by oxidizing glucose to pyruvate.
After pyruvate is oxidized, the citric acid cycle completes the energy-yielding oxidation of organic molecules.
Pyruvate oxidation
and
Citric acid cycle
.
Pyruvate oxidation
: is the step that connects glycolysis and the Krebs cycle.
The oxidation of pyruvate occurs in the mitochondria's inner membrane. During cellular respiration, all of the CO2 that occurs is generated in the mitochondria.
Citric acid cycle
: is a series of chemical reactions used by all aerobic organisms to generate energy through the oxidation of acetyl-CoA derived from carbohydrates, fats and proteins into carbon dioxide and chemical energy in the form of guanosine triphosphate (GTP).
Oxidative Phosphorylation
: is the metabolic pathway in which the mitochondria in cells use their structure, enzymes, and energy released by the oxidation of nutrients to reform ATP.
The two main steps of oxidative phosphorylation are electron transport and chemiosmosis, both of which use the movement of charged particles to transfer energy.