Biology Ch. 8 Terms
Terms
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- energy
- expressed in kJ or kcal, required to do work
- work
- any change in state of motion or matter, requires energy
- energy conversion
- energy changing forms
- Potential energy
- capacity to do work
- Kinetic energy
- energy of motion
- 1st law of termodynamics
- conservation of energy
- 2nd law of thermodynamics
- Every energy conversion increases the entropy of the universe.
- Entropy
- spreading of energy
- Metabolism
- sum of chemical activities in an organism
- Anabolism, Anabolic reactions
- Processes that builed complex molecules from simpler ones.
- Catabolism, catabolic reactions
- processes that break down complex molecules into simpler ones.
- Free energy
- energy available to do work in a chemical reactiion, changes depend on bond energies and concentrations of reactants/products
- bond energy
- energy required to break a bond
- dynamic equilibrium
- forward and reverse reaction rates are equal
- exergonic reactions
- the products have less free energy than the reactants, energy is released, spontaneous, favored reaction
- endergonic reactions
- the products have more free energy than the reactants, energy must be supplied from the exergonic reactions, not spontaneous
- coupled reaction
- endergonic and exergonic reactions couple to provide the free energy for the endergonic reaction
- ATP
- the main energy currency in cells; a nucleotide with adenine base, ribose sugar, and a chain of 3 phosphate groups;
- phosphorylated compounds
- the inorganic phosphate is removed from ATP transferred onto another compound rather than being immediately released; usually coupled with ATP hydrolysis
- Redox reactions
- reduction, gain electrons; oxidation, lose electrons; both occur simultaneously in cells;
- nicotinamide adenine dinucleotide (NAD+)
- a common intermediate acceptor
- NADP+/NADPH
- important in photosynthesis
- FAD/FADH2
- flavin adenine dinucleotide
- Cytochromes
- small iron-containing proteins; iron serves as electron acceptor
- Enzymes
- regulate chemical reactions in living organisms; work by lowering the activation energy of a reaction; lower activation energy by forming a complex with the substrate(s)
- catalyst
- substance that increases the rate of a chemical reaction without being consumed in the reaction;
- activation energy
- the energy required to break existing bonds
- enzyme-substrate complex
- binding of an enzyme with a substrate (reactant)
- active site
- the site where the substrate(s) binds to the enzyme
- induced fit
- when the enzyme-substrate complex forms, there are typically shape changes in the enzyme and substrate(s)
- cofactors
-
needed in order for an enzyme to function; can be organic or inorganic; organics(coenzymes)=ATP, NADH, NADPH, FADH2
inorganics=metal ions like Ca2+, Mg2+, Fe3+, etc - inhibitors
- reduce or eliminate catalytic activity
- activators
- allow or enhance catalytic activity
- allosteric site
- a receptor site on an enzyme where an inhibitor or activator can bind
- feedback inhibition
- where the last product in a metabolic pathway binds to an allosteric site of an enzyme in an early step of the pathway (often the first) and inhibits activity of the enzyme
- irreversible inhibition
- enzyme is permanently inactivated or destroyed; includes many drugs and toxins
- reversible inhibition
- if inhibitor is removed, the enzyme activity can be recovered
- competitive inhibition
- inhibitor is similar in structure to a substrate; competes with substrate for binding to the active site
- noncompetitive inhibition
- binds at allosteric site, alters enzyme shape to make active site unavailable