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What is Metabolism?
The totality of an organism’s chemical reactions; manages the material and energy resources of the cell
Metabolic pathways begin with…
A specific molecule and ends with a product
A catabolic pathway…
leads the RELEASE energy by the BREAK DOWN complex molecules into similar compounds
Example of a catabolic pathway
Cellular respiration
Anabolic pathways…
CONSUME energy to BUILD complex molecules from similar ones
What is energy?
Capacity to work
What is Kinetic energy(KE)?
Associated with motion; thermal energy & heat
what is potential energy (PE)?
Energy that matter posses because if it’s location or structure; chemical energy
1st law of thermodynamics:
Energy can be transferred and transformed but not created or destroyed
What is thermodynamics?
The study of energy transformations
2nd law of thermodynamics:
In every energy transfer the PE if the final state is less than the PE of the initial state
What is Free energy(🔼G)?
Part of a system’s energy that is able to perform when the temperature of a system is uniform
Exergonic reaction…
Energy is released; occurs spontaneously; 🔼G<0
Endergonic reaction…
Requires energy; absorb/ require free energy; 🔼G>0
What is ATP
The cell’s energy shuttle; ribose, adenine, and 3 phosphate groups
When ATP transfers one phosphate group through_______, it becomes____
Hydrolysis, ADP
When ADP transfers one phosphate group through_____ it becomes ___
Phosphorylation, ATP
What is a catylsist?
A chemical agent that speeds up a reaction without being consumed by the reaction
Ex of a catalytic protein
Enzyme; ase= enzyme
Activation Energy (EA)
The initial energy needed to start a chemical reaction
Enzymes speed up reactions by…
Lowering the EA of the reaction but without altering the 🔼G of the reaction
In catalysis, how do enzymes or other catalysts speed up specific reactions?
By lowering the EA barrier
Enzymes do not affect the change in 🔼G…
They hasten reactions that would occur eventually
What is an Active site?
Region on the enzyme where the substrate binds
What is step 1 of an enzymatic reaction?
Substrates enter active site
What is step 2 of an enzymatic reaction?
Substrates are held in active site by weak interactions
What is step 3 of an enzymatic reaction?
The active site lowers EA
What is step 4 of an enzymatic reaction?
Substrates are converted into products
What is step 5 of an enzymatic reaction?
Products are released
What is step 6 of an enzymatic reaction?
Active site is now available for new substrates
An enzyme has an…
Optimal temperature in which it can function
Each enzyme has an…
Optimal pH in which it can function
As the enzyme loses its precise shape, it’s efficiency decreases until…
It becomes denatured; can no longer function
Many enzymes require
Nonproteins, aka cofactors
If the cofactor is organic…
It is referred to as a coenzyme
What is an example of a cofactor?
Vitamins
What are Competitive inhibitors?
Molecules that compete with the substrate for the active site on the enzyme; may bind reversible or irreversibly to the active site.
What is an example of a competitive inhibitor
Poisons
What are non competitive inhibitors?
Molecules that don’t directly compete with the substrate molecule to bind at the active site; they impede enzyme activity by binding to another part of the enzyme. This causes the enzyme to change shape, often rendering the active site nonfunctional.
Assuming abundant substrate, An increase in enzyme concentration will lead to…
An increase in production of the final product
If the enzyme concentration is held constant and the substrate concentration is increased, the rate of the reaction will
increase until the enzyme is saturated (functioning at maximum efficiency) and the production of the final product is constant.
Many enzyme regulators bind to…
Allosteric sites on the enzyme; which is a specific binding site but NOT the active site
Once bound, the shape of the enzyme is changed and can stimulate…
Enzyme activity(allosteric activator) or inhibit enzyme activity(allosteric inhibitor)
What happens during feedback inhibition?
The end product of a metabolic pathway shuts down the pathway by binding to the allosteric site of the enzyme in the pathway
Feedback inhibition…
Increases the efficiency of the pathway by turning it off when the end product accumulated in the cell.
ATP powers cellular work by…
coupling energy releasing (exergonic) reactions to energy requiring (endergonic) reactions.
Enzymes catalyze the conversion…
of a substrate to a final product by lowering the energy of activation.
Enzymes are specific in the reactions they catalyze…
because of the molecular shape and charge of their active sites.
Factors that change the shape of the active site of enzymes…
influence enzyme activity.
enzymes regulate biological activities
by the rate of their reactions, often governed by feedback inhibition and activation.
enzyme and substrate concentrations can affect
the rate of reactions.
Note 
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