AP BIO UNIT 3 Flashcards
Metabolism
All of the chemical reactions in an organism
Metabolic Pathways
Series of chemical reactions that either build complex molecules or break down complex molecules
Catabolic Pathway
Pathways that release energy by breaking down complex molecules into simpler compounds
Anabolic Pathway
Pathways that consume energy to build complicated molecules from simpler compounds
Energy
The ability to do work
Organisms need energy to…
survive and function. A loss in energy flow results in death.
Kinetic Energy
Energy associated with motion.
Thermal Energy
Energy associated with the movement of atoms or molecules.
Potential Energy
Stored energy.
Chemical Energy
Potential energy available for release in a chemical reaction.
Thermodynamics
The study of energy transformations in matter. These laws apply to the universe as a whole.
1st Law of Thermodynamics
Energy cannot be created or destroyed. Energy CAN be transferred or transformed. (Example: the chemical energy (potential) stored in the nut will be transformed into kinetic energy for the squirrel to climb the tree.)
2nd Law of Thermodynamics
Energy transformation increases the entropy (disorder) of the universe. During energy transfers or transformations, some energy is unusable and often lost as heat. (Example: as the squirrel climbs the tree, some energy is released as heat)
∆G
Change in free energy
∆H
Change in total energy
T
Absolute temperature (K)
∆S
Change in entropy
Law of Thermodynamics Formula
∆G = ∆H - T∆S
Exergonic Reactions
Reactions that release energy (Example: cellular respiration)
Endergonic Reactions
Reactions that absorb energy (Example: photosynthesis)
Mechanical Work
Movement (Example: beating cilia, movement of chromosomes, contraction of muscle cells)
Transport Work
Pumping substances across membranes against spontaneous movement
Chemical Work
Synthesis of molecules (Example: building polymers from monomers)
ATP
(Adenosine Triphosphate) Molecules that organisms use as a source of energy to perform work
Organisms obtain energy…
By breaking the bond between the 2nd and 3rd phosphate in a hydrolysis reaction. (ATP –> ADP)
Phosphorylation
The released phosphate moves to another molecule to give energy
Regeneration of ATP
ADP can be regenerated to ATP via the ATP cycle. (ATP + H20 –> ADP + Pi)
Enzymes
Macromolecules that catalyze (speed up) reactions by lowering the activation energy. (Are not consumed by the reaction, type of protein, enzyme names end in “ase”)
Enzyme Structure
The enzyme acts on a reactant called a substrate
Active Site
Area for substrate to bind
Enzyme Function
Active site is open, substrates are held in active site by weak interactions, substrates are converted to products, products are released.
Induced Fit
Enzymes will change shape of their active site to allow the substrate to bind better.
Enzyme Catabolism
Enzyme helps break down complex molecules.
Enzyme Anabolism
Enzyme helps build complex molecules.
Effects on Enzymes
Enzymes are proteins, which means their 3D shape can be affected by different factors.
Factors that Affect the Efficiency of Enzymes
Temperature, pH, Chemicals
Optimal Conditions
The conditions (temperature & pH) that allow enzymes to function optimally.
Enzyme Activity (Temperature)
The rate of enzyme activity increases with temperature (due to collision) up to a certain point). After a certain point, the enzyme will denature.
Enzyme Activity (pH)
Enzymes function best at a specific pH. Being outside the normal pH range can cause hydrogen bonds to break changing the shape of the enzyme.
Enzyme Cofactors
Non-protein molecules that assist enzyme function. Inorganic cofactors consist of metals. Can be bound loosely or tightly.
Holoenzyme
An enzyme with the cofactor attached.
Coenzymes
Organic cofactors. (Example: vitamins)
Enzyme Inhibitors
Reduce the activity of specific enzymes.
Permanent Inhibition
Inhibitor binds with covalent bonds. (Example: toxins and poisons)
Reversible Inhibition
Inhibitor binds with weak interactions.
Competitive Inhibitors
Reduce enzyme activity by blocking substrates from binding to the active sites. Inhibition can be reverse with increased substrate concentrations.
Noncompetitive Inhibitors
Bind to the area other than the active site (allosteric site), which changes the shape of the active site preventing substrates from binding.
Regulation of Chemical Reactions
A cell must be able to regulate its metabolic pathways. Control where and when enzymes are active. Switch genes that code for enzymes on or off.
Allosteric Enzymes
Allosteric enzymes have two binding sites. 1 active site, 1 allosteric site (regulatory site, site other than the active site)
Allosteric Regulation
Molecules bind (noncovalent interactions) to an allosteric site which changes the shape & functions of the active site. May result in inhibition (by an inhibitor) or a stimulation (by an activator) of the enzymes activity.
Allosteric Activator
Substrate binds to allosteric site & stablilizes the shape of the enzyme that the active sites remain open.
Allosteric Inhibitor
Substrate binds to allosteric site and stabilizes the enzyme shape so that the active sites are closed (inactive form).
