Metabolism
Sum of all chemical reactions occurring in an organism
Metabolic pathway
Begins with a specific molecule and ends with a product. Each step is catalyze by a specific enzyme
Catabolic pathways
Release energy. Break down complex molecules into simpler compounds
Anabolic pathways
Consume energy to build complex molecules from simpler ones. Ex: synthesis of protein from amino acids
Energy
The capacity to cause change. Exists in various forms, some of which can perform work
Kinetic energy
Energy associated with motion
Potential energy
Energy that matter possesses because of its location or structure
First law of thermodynamics
Energy can be transferred and transformed but it cannot be created or destroyed. Sunlight is converted into chemical energy by photosynthesis
During every energy transfer/transformation…
Some energy is unusable and is often lost as heat
Second law of thermodynamics
Every energy transfer/transformation increases the entropy of the universe
Entropy
A measure of molecular disorder or randomness
Spontaneous processes
Occur without energy input and can happen quickly or slowly. For a process to occur without energy input, it must increase the entropy of the universe
Disorder
Happens spontaneously
Organization
Requires energy
Order and disorder
Cells create ordered structures from less ordered materials. Organisms also replace ordered forms of matter and energy with less ordered forms
Free energy
The energy available to work. The symbol G
Enthalpy
Energy contained in a molecules chemical bonds
Delta G is positive
When products contain more free energy than reactants
Delta G is negative
When reactants contain more free energy than products
Endergonic reaction
A reaction requiring an input of energy (not spontaneous) Delta G is positive
Exergonic reaction
A reaction that releases free energy (spontaneous). Delta G is negative
ATP is composed of
Ribose (a sugar), adenine (a nitrogenous base), and three phosphate groups
Hydrolysis of ATP
ATP is turned into ADP by hydrolysis.
Activation energy
Extra energy needed to get a reaction started.
Catalysts
Substances that lower activation energy of a reaction. Cannot make an endergonic reaction spontaneous.
Enzyme
Biological catalyst. Most enzymes are proteins
Substrate
The reactant that an enzyme acts on is called the enzymes substrate
Enzyme-substrate complex
The enzyme binds to its substrate, forming an enzyme-substrate complex
Active site
The region on the enzyme where the substrate binds
Induced fit
Induced fit of a substrate brings chemical groups of the active sit into positions that enhance their ability to catalyze the reaction
Cofactors
Usually metal ions, found in the active site participating in catalysts (Zn, Mn, Mo)
Coenzymes
Organic molecule cofactors which include vitamins
Inhibitor
Substance that binds to enzyme and decreases it’s activity
Competitive inhibitors
Bind to the active site of an enzyme, competing with the substrate
Noncompetitive inhibitors
Bind to another part of an enzyme, causing the enzyme to change shape and making the active site less effective
Allosteric enzymes
Exist in either an active or inactive state
Allosteric site
Allosteric enzymes possess an allosteric site where molecules other than the substrate bind
Allosteric inhibitors
Bind to the allosteric site to inactivate the enzyme
Allosteric activators
Bind to the allosteric site to activate the enzyme
Biochemical pathways
A series of reactions in which the product of one reaction becomes the substrate for the next reaction
Feedback inhibition
The end product of a metabolic pathway shuts down the pathway
Feedback inhibition prevents a cell
From wasting chemical resources by synthesizing more product than is needed