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Introduction to Metabolism - Coggle Diagram
Introduction to Metabolism
An organism's metabolism
Metabolic Pathways
Anabolic pathways
Consume energy to build complex molecules from simpler ones
"Uphill"
Ex: synthesis of amino acids
Catabolic pathways
Release cellular energy by breaking down complex molecules into simpler compounds
"Downhill"
Ex: Cellular respiration
A series of chemical reactions that build or break things down
Bioenergetics
Laws of thermodynamics
2nd law
- conversion of energy results in loss of heat by living things
Every energy transformation increases the
entropy
of the universe
Entropy
- disorder/randomness
1st law
- energy can be transferred or transformed but can't be created or destroyed
spontaneous process
- occurs without energy input, can happen fast or slow
↓ ▲G
The study of how
energy
flows through living organism
Energy
- capacity to cause change, can be used to do work
Kinetic energy
- energy associated with motion
Thermal energy
-
kinetic energy
associated with random movement
Heat
-thermal energy transferred from one object to another
Potential energy
- the potential of energy that can happen
Chemical energy
- potential energy available for release in a chemical reaction
Metabolism
Anabolic
reactions +
catabolic
reactions
Totality of an organism's chemical reactions
The free energy change of a reaction
Free energy and metabolism
Exergonic reaction
- proceeds with a net release of ▲G to the surroundings
"Energy outward"
Reactants > products (spontaneous)
Endergonic reaction
- absorbs ▲G from the surroundings
"Energy inward"
Reactants < Products (non-spontaneous)
Equilibrium and metabolism
-
Isolated
Eventually reach equilibrium and can then do no work
Open
Energy & matter can be transferred between systems & it's surroundings
Free energy
Portion of a system's energy that can do work when temperatures and pressure are uniform throughout the system, as in a living cell
"The energy available"
Often represented as
▲G
▲ = change
▲G=▲H-T▲S
▲H = Enthalpy(total energy) T= Temperature in Kelvin..... ▲S = entropy (disorder)
▲G- = spontaneous (more stable) ▲G+ = non-spontaneous (less stable) ▲G 0 = equilibrium
More potential energy = more ▲G
ATP powers cellular work
Energy coupling
- use of an exergonic process to drive an endergonic one
ATP (adenosine triphosphate)
- composed of ribose, adenine (a nitrogenous base), & 3 phosphate groups
The triphosphate tail is the chemical equivalent of a compressed spring
Regeneration of ATP
- free energy needed to
phosphorylate
ADP exergonic energy needed to make ATP
Phosphorylation
- transfer of a phosphate group from
ATP
to another molecule
Phosphorylation intermediate
- More reactive than the original molecule (less stable with more free energy)
Enzymes speed up metabolic reactions
Catalyst
- speeds up a reaction without being consumed by the reaction
Enzyme
- acts as a catalyst to speed up a specific reaction
Enzyme-substrate complex
- enzyme that binds to its substrate
Enzymes are very specific, must fit exactly the size with a specific enzyme
Increase in reaction speed = increase in substrate concentration
All enzymes utilized = saturation
Activation energy
- initial energy needed to break the bonds of the reactants
Substrate
-Reactant that the enzyme acts on
Active site
- pocket or groove on an enzyme that binds to the substrate
Enzyme inhibitors
- certain chemicals inhibit the action of specific enzymes
Competitive inhibitors
- closely resembles the substrate and can bind to the activation site on the substrate
Non-competitive inhibitors
- causes enzyme to change shape, making binding less effective
Toxins & poisons are often irreversible enzyme inhibitors
Regulation of enzyme activity
Allosteric regulation
- occurs when a regulatory molecule binds to a protein at one site & affects the proteins function at another site
Mostly made from polypeptide subunits, each with it's own activation site
Cooperativity
- substrate binding to one active site triggers a shape change in the enzyme that stabilizes the active form for all other site
Feedback inhibition
- method of metabolic pathway acts as an inhibitor of an enzyme within a pathway
