Energy and Enzymes Flashcards
Energy (what it is and forms)
- a force that can accomplish work
- 2 major forms
- potential
- kinetic
Potential energy (what it is and examples)
- energy of position (stored energy)
- ex: chemical energy (in bonds)
Kinetic energy (what it is and example)
- energy of motion
- ex: mechanical energy
Metabolism (what it is and types)
- sum of all chemical reaction in a living organism
- includes
- anabolism
- catabolism
Anabolism
- Biosynthesis reactions: building
- Endergonic: requires energy
Catabolism
- degrative reactions: breaking down
- exergonic: energy releasing
Chemical reactions (components and directions)
Components: -Substrate: what goes in (reactant) -product: what comes out Directions: -Forward -reverse
Factors affecting chemical reactions
- law of mass action
- activation energy
- enzymes
Law of mass action
- forward reactions
- higher reactants= higher products
- high product= slow down making of product
Activation energy
- minimum energy required for reactants to overcome activation energy barrier –> transition state –> product
- Sources:
- collision from other molecules
Enzymes (structure, function)
Structure:
-protein based molecules
-substrate specific
Function:
-reduce activation energy
-biological catalysts:
-speed up reactions
-does not get used up or changedModels for Enzyme Binding
- lock and key mechanism
2. induced fit model
Lock and key mechanism
- substrate fits an enzyme like a key to a lock
- problem: doesn’t explain reversible reactions
Induced fit model
- substrates approximately fit enzyme
- after binding –> conformational change for a better fit
How enzymes work (steps)
-enzyme binds with a substrate converting them to products
- substrate contacts active site of the enzyme
- enzyme- substrate complex forms
- substrate is transformed, broken down, or compounded with other substrates
- transformed substrate (products) released
- unchanged enzyme free to interact with other substrates
Enzyme sites
- active site: where substrate binds
2. allosteric site: where molecules other than the substrate bind
Types of enzymes
- simple enzymes: proteins with catalytic activity
2. holoenzymes: conjugated enzymes
Holoenzymes (protein and nonprotein portion)
Protein portion: apoenzyme
nonprotein portion:
-cofactor: inorganic ions (zinc, iron, magnesium, calcium)
-coenzyme: organic molecules (vitamins/minerals) ex: NAD+, NADP+, FAD, coenzyme A
Factors influencing enzymatic rate (6)
- enzyme concentration
- substrate concentration
- temperature
- pH
- enzyme catalytic rate
- affinity
Enzyme catalytic rate
inherent speed of an enzyme
Substrate concentration
increasing substrate, increasing activity until saturation
-saturation: enzymes active sites are filled with substrate
Enzyme concentration
increase in enzymes= increase in maximum rate
Affinity
How tightly a substrate binds to an active site
high affinity –> increase reaction rates
Temperature
- enzymes have an optimal temperature
- increases rate of collision and reaction
- too much –> denature enzyme
pH
- enzymes have an optimal pH
- extreme pH (acidic or basic) –> denature enzyme
Enzyme regulation
- allosteric regulation
2. inhibitors
Allosteric regulation (what it is and examples)
-modulators weakly bind to allosteric site
- activator: increase catalytic rate, increase affinity to substrate
- inhibitor: decreases enzymatic activity
Inhibitors
- competitive: chemicals that bind to the active site
ex: penicillin, sulfanilamide - non-competitive: chemicals that bind to the allosteric site or cofactors
ex: cyanine, fluoride
