Enzymes work by reducing the energy of activation.
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Most enzymes are _____.
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Most enzymes are proteins.
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Imagine a candy bar sitting on a table in front of you. Which specific types of energy are present in the candy bar?
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The bar has some heat in it, has energy stored in the form of chemical bonds (which is where the Calories come from), and has the potential to fall off the table.
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Some people restate the second law of thermodynamics this way: "When energy changes forms, some energy is always lost." Why is this statement incorrect?
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This statement implies that some energy is destroyed. the first law of thermodynamics says that energy is never destroyed. If you were to say "lost as heat," the statement would be more correct.
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Entropy is a tendency toward _____.
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a decrease in order. entropy is the tendency for orderly things to become more disorderly.
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Which of the following represents an increase in entropysorting coins into like groups
rearranging the books on a shelf
turning off an oven
flattening a lump of dough
putting trash in a trashcan
smashing a drinking glass
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A broken glass has more pieces than a whole glass. A broken glass is more disordered.
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Where does the energy that life uses to combat entropy come from?
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The majority of living things get their energy from the sun, either directly through photosynthesis or eating other life that benefited from photosynthesis
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Which of the following is true about the reaction of ADP and phosphate to form ATP?The reaction releases energy.
The reaction requires activation energy.
The reaction combines two unstable reactants into a stable product.
The reaction is endergonic.
The reaction combines two products to form a reactant.
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Connecting ADP and P is endergonic, breaking ATP apart into ADP and P is exergonic.
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Which of the following reactions could be coupled with the synthesis of ATP from ADP and phosphate the breakdown of sugar into water and carbon dioxide
the assembly of amino acids into a protein
the assembly of sugar from water and carbon dioxide
the breakdown of ATP into ADP and phosphate
answer
the breakdown of sugar into water and carbon dioxide. This exergonic reaction is used to power the endergonic assembly of ATP.
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What name is given to the reactants in an enzymatically catalyzed reaction?
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Substrate. This is the name given to the reactants in an enzymatically catalyzed reaction.
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As a result of its involvement in a reaction, an enzyme _____.
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unchanged. Enzymes are not changed as a result of their participation in a reaction.
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The enzyme amylase in human saliva breaks starch polymers down into smaller sugar units. However, it cannot break down cellulose polymers. Both are made of glucose monomers, but in cellulose the monomers are linked together in a different shape than starch. Why can't amylase digest cellulose?
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The bonds of cellulose do not fit properly in the active site. Changing the orientation of a bond often prevents an enzyme from affecting a substrate.
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How is an intermediate best defined?
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An intermediate is a product of one reaction that will serve as a reactant in another reaction. An intermediate is a product that is not finalized.
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How do competitive inhibitors stop a chemical reaction?
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Competitive inhibitors bind in the active site of an enzyme.This prevents the desired substrate from making use of the enzyme.
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Why does feedback inhibition occur at the beginning of a metabolic pathway instead of in the middle?Why does feedback inhibition occur at the beginning of a metabolic pathway instead of in the middle?
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because all of the initial substrates would still be used up if the pathway were stopped in the middle.The benefit of stopping a metabolic reaction at the beginning is it allows you to keep the reactants or use them in a different pathway.
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Most enzymes do not work if the temperature is raised too much. Why is this?
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Enzymes denature at higher temperatures.Incorrect temperature, pH, and salt concentrations cause an enzyme to change shape.
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E. coli bacteria can use the enzyme lactase to digest lactose and use it as an energy source. However, it is more efficient for bacteria to use glucose as an energy source if it is present. Which of the methods of regulating enzyme activity would be most energy efficient for a bacterium that has plenty of glucose?
answer
the bacterium should stop production of lactase.Producing lactase enzyme costs energy, which would be wasted if there was plenty of glucose around.
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energy
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capacity to do work
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work
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force acting on an object that causes the object to move
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potential energy
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stopped energy
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kinetic energy
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energy of movement
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1st Law of Thermodynamics
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conservation of energy energy can niether be created or destroyed, but can change form. Total energy with in a closed system remains constant
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2nd Law of Thermodynamics
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entrophy increases in a closed system
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entrophy
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amounts of randomness and disorder in a system
less energy (6CO2 + 6H2O)
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chemical reaction
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process that forms or breaks chemical bonds
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exergonic chemical reactions
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reaction releases energy (energy exits)
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endergonic chemical reactions
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requires energy input (energy in)
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activation energy
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extra energy needed to start reaction negatively charged electron shells of atoms repel each other
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ATP
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ADP+Pi
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nucleotides
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monomer, function energy carrier or intercellular messenger, ATP is an example
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Kind of reaction ATP is synthesised
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endergonic
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kind of reaction ATP is broken down with
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exergonic
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ATP, electron carriers, coupled reactions
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all energy transport within a cell
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how do cells control all of the biochemical reactions required to maintain balance within each cell?
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catalyst and enzymes
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catalysts
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molecules increases the are of a reaction without being premaritally changed
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characteristics of a catalyst
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1)functions by lowering the activation energy
2) cant make an endergonic reaction occur spontaneously
3) They are not changed or consumed by the reaction
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Enzymes
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molecules that catalyzes a specific biological reaction
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characteristics of enzymes
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1) all are catalyst
2)highly specific
3) activity is highly regulated
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Enzymes promote chemical reaction
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1) substance enters the active cell in a specific orientation.
2)substance enzymes binding causes both to change shape
3)faciliate reaction
4) products no longer fit in active site and they are then released
5) enzymes will revert to original shape
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metabolism
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sum of all the chemical reactions inside a cell
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metabolic pathways
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cellular reactions that over link by reactants and products
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synthesis of inactive enzymes
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must be activated either by environment or by other protiens
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competitive inhibition
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substance binds to active site
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non competitive inhibition
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molecules bind to site distinct from active site
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allosteric regulation
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other shape allosteric enzyme switch easily between 2 shapes
- active site and regulatory site shape is determined by reversible binding to regulatory site by allosteric activator inhibitor.
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feedback inhibition
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a special case of allosteric regulation
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environment
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PH temp, salt ion, concentration
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competitive inhibitor
answer
methanol
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