Chapter 8: Introduction to Metabolism Flashcards
Metabolism
Totality if an organism’s chemical reactions
Metabolic pathway
A specific molecule is altered in a series of steps to produce a product
Catabolic pathways
Energy is released, complex molecules are broken down. Ex. Cellular respiration
Anabolic pathways
Energy is consumed, simple molecules are built up to create more complex ones. Ex. Using amino acids to make proteins
Energy
The capacity to cause change or to do work
Bioenergetics
The study of how energy flows through living organisms
First law of thermodynamics
Energy cannot be created or destroyed, but it can be transferred and transformed
Second law of thermodynamics
Every energy transfer or transformation increases the entropy of the universe
Spontaneous process
Occurs without energy input, increases entropy
Nonspontaneous process
Requires energy input, decreases entropy
Free energy
The portion of a system’s energy that can do work
Exergonic reaction
Energy is released, free energy is negative
Endergonic reaction
Energy is absorbed, free energy is positive
Chemical work
Pushing endergonic reactions polymerization
Transport work
Pumping substances across membranes against the direction of spontaneous movement
Mechanical work
Beating cilia, muscle contraction, etc
Energy coupling
The use of an exergonic process to drive and endergonic one
Phosphorylated intermediate
More reactive (less stable, more free energy) than the original molecule
Catalyst
Chemical agent that speeds up a reaction without being consumed by the reaction
Enzyme
A macromolecules (typically a protein) that acts as a catalyst to speed up a specific reaction
Activation energy
Initial energy needed to break the bonds of the reactants
Substrate
Reactant that an enzyme acts on
Enzyme-substrate complex
Formed when the enzyme binds to its substrate
Lock and key metaphor
Only the right key (substrate) will fit in the lock (enzyme)
Induced fit
Enzyme tightens binding after initial contact with substrate
Influences of enzyme activity
Concentration of substrate, temperature, pH, chemicals/inhibitors
Competitive inhibitor
Closely resembles the substrate, can bind to the enzymes active site
Noncompetitive inhibitor
Binds to another part of an enzyme, causing the enzyme to change shape, making active site less effective
Cofactors
No protein helpers that bind to the enzyme with the substrate
Coenzymes
Organic cofactors
Allosteric regulation
A protein’s function at one site is affected by binding of a regulatory molecule to a separate site
Feedback inhibition
The end product of a metabolic pathway shuts down the pathway
