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What are proteins that function as biological catalysts?
enzymes
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What are RNA molecules that function as biological catalyst?
ribozymes
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List the three characteristics of a catalyst.
- Increases the rate of a reaction.
- Is not itself changed at the end of the reaction.
- Does not change the nature of the reaction or its final result.
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What is the amount of energy required for a reaction to occur?
activation energy
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What effect to enzymes have on the activation energy of a reaction?
They lower it
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Why are enzymes essential to life?
They make reactions occur at a rate that is fast enough to sustain life.
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What part of an enzyme takes part in catalyzing a reaaction?
the active site
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What are the reactant molecules on which an enzyme works?
the substrate
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What model of action describes how an enzyme and its substrate interact?
the lock-and-key model
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What model describes how an enzyme changes its configuration to fit together with its substrate?
the induced-fit model
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The temporary union of an enzyme and its substrate is referred to as what?
the enzyme-substrate complex
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What molecules are the result of the enzyme-substrate complex?
the products
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With the except of enzymes named before the establishment of international nomenclature, what suffix ends the names of all enzymes?
-ase
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How are classes of enzymes named?
according to their activity or job category
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What are enzymes that promote hydrolysis?
hydrolases
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What are enzymes that catalyze the removal of phosphate groups?
phosphatases
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What are enzymes that catalyze dehydration synthesis?
synthases and synthetases
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What are enzymes that remove hydrogen atoms from their substrates?
dehydrogenases
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What are enzymes that add a phosphate group to particular molecules?
kinases
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What are enzymes which rearrange atoms within their substrate molecules to form structural isomers, such as glucose and fructose?
isomerases
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Different organs may have different ìmodelsî of the same enzyme that differ in one or a few amino acids. What are these different models called?
isoenzymes
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Within the temperature range from 0 degrees Celsius to 37 degrees Celsius, what happens to the activity of an enzyme as the temperature rises?
activity increases
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What happens to the activity of enzymes within the human body as the temperature rises above 37 degrees Celsius?
it decreases
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What is the narrow range of pH within which an enzyme exhibits its peak activity?
the pH optimum
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What happens to the activity of an enzyme if the pH is not with the pH optimum for that enzyme?
it decreases
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Why does the activity of an enzyme decrease it the pH is not within its optimum range?
the configuration of the enzyme changes
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What are inorganic substances which are necessary for an enzyme to function properly?
cofactors
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What are organic molecules that are necessary for enzymes to function properly?
coenzymes
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What are inactive, precursor forms of enzymes?
zymogens
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What is the process in which a phosphate group is added to a molecule?
phosphorylation
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What is the process in which a phosphate group is removed from a molecule?
dephosphorylation
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At any given level of enzyme concentration, the rate of product formation will increase as the substrate concentration increases. When the relationship between the substrate concentration and the reaction rate reaches a plateau, what has happened to the enzyme?
It has been saturated
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Some enzyme reactions are reversible. What principle states that the reaction will be driven from the side of the reaction where the concentration is the highest?
law of mass action
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What is a sequence of enzymatic reactions that begins with an initial substrate, progresses through a number of intermediates, and ends with a final product?
a metabolic pathway
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What is a form of negative feedback which prevents the over accumulation of the end product of a metabolic pathway?
end-product inhibition
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What mechanism occurs when the end product of a metabolic pathway combines with a part of an enzyme other than the active site to inhibit the pathway.
allosteric inhibition
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What is an inherited defect in one of the genes for an enzyme that is part of a metabolic pathway?
an inborn error of metabolism
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What is the flow of energy through living systems?
bioenergetics
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What principle states that energy can be neither created nor destroyed, but it can be transformed from one form to another?
the first law of thermodynamics
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What is the degree of disorganization of a systems total energy?
entropy
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What principle state that the amount of entropy increases with each energy transformation?
the second law of thermodynamics
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As entropy increases, what happens to the amount of energy available to do work?
It decreases
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What are chemical reactions that require an input of energy?
endergonic reactions
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What type of reactions release energy as they proceed?
exergonic reactions
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What is the amount of heat required to raise the temperature of one gram (one cubic centimeter or one milliliter) one degree Celsius?
a calorie
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What unit of measure is usually used for foods?
the kilocalorie (Calorie)
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Coupled reactions involve what two types of reactions?
exergonic and endergonic
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The energy released by most exergonic reactions in the cell, either directly, or indirectly , drive the formation of what molecule?
adenosine triphosphate
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What is the full term for ATP?
adenosine triphosphate
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What is the universal energy carrier in living systems?
adenosine triphosphate
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What are the three things ATP is used for?
- Biomechanical movement
- Transportation
- To make reactions go
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What is the reduction of a molecule?
the gaining of electrons
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What is the oxidation of a molecule?
the loss of electrons
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What is a molecule that donates electrons to another?
a reducing agent
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What is a molecule that accepts electrons?
an oxidizing agent
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Name two molecules that are important in transferring hydrogen from one molecule to another. They are coenzymes that act as hydrogen carriers.
- nicotinamide adenine dinucleotide (NAD)
- flavin adenine dinucleotide (FAD)
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What are the reduced forms of NAD and FAD?
NADH + H+ and FADH2
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