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87 Cards in this Set
- Front
- Back
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All chemical reactions and physical workings of the cell.
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metabolism
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enzymes are involved in the breakdown of complex organic molecules in order to extract energy and form simpler products
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catabolism
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enzymes are involved in the use of energy from catabolism in order to synthesize macromolecules and cell structures from precursors (simpler products)
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anabolism
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Most enzymes are composed of...
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proteins; some may require cofactors
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Why do enzymes act as organic catalysts?
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to speed up the rate of cellular reactions
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What is required for the cellular reaction to proceed?
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enzyme must lower the activation energy
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What unique characteristics do enzymes have?
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shape, specificity, and function
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At what rate to do enzymes allow metabolic pathways to proceed?
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at a speed compatible with life
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target molecules are called
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substrates
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substates attach to what on the enzyme?
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the active site
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How are enzymes compared to their substrates in size?
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enzymes are much larger
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enzymes associate closely with substrates but..
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do not become integrated into the reaction products
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enzymes are not used up or...
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permanently changed by the reaction, but they can be recycled
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enzymes are greatly affected by ,,,
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temperature and pH
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enzymes can be regulated by...
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feedback and genetic mechanisms
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made up of protein
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enzymes
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made up of RNA
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ribozymes
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all enzymes can create a specific...
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active site
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simple enzyme is..
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protein alone
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conjugated enzyme is...
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protein plus a cofactor or coenzyme
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protein part of an enzyme is called...
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apoenzyme
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protein + cofactor or coenzyme is called...
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holoenzyme
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the folding of enzymes creates...
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specific active sites
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the way a substrate specifically binds the active sites on the enzyme is like...
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a hand in a glove
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metallic cofactors
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iron, copper, magnesium
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what is the purpose of cofactors?
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bind to and activate the enzyme
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transient carrier coenzyme does what?
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alters a substrate by removing a chemical group from one substrate and adding it to another substrate ex. vitamins (NAD, FAD)
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conjugated enzymes contain what for it to function as a catalyst?
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metallic cofactor, coenzyme, or both
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where do exoenzymes work?
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outside of the cell
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where do endoenzymes work?
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inside of the cell
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active enzymes that are always present
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constitutive
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active enzymes that are present only when needed
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regulated
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regulated enzymes work like this...
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induced by the presence of the substrate or repressed in the presence of plenty of product
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Exoenzymes upon release from the cell they become...
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active
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Endoenzymes remain in the cell and are...
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active inside the cell
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constitutive enzymes are present in...
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constant amounts
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regulated enzymes are either...
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reduced or repressed
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condensation reactions do what?
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synthesis of large molecules like proteins, starch, DNA, and RNA occur via ligation of smaller substrates. These reactions release water and require the input of ATP
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hydrolytic reactions do what?
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breakdown of large molecules and consumes water
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reduction
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gain of an electron (or hydrogen)
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oxidation
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loss of an electron (or hydrogen)
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transfer reactions
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add or remove a functional group (methyl group, acetyl group, phosphate group)
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What are the six major classes of enzymes
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oxidoreductases, transferases, hydrolases, lyases, isomerases, and ligases
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pathogens excrete exoenzymes that help them to:
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avoid the host immune response, and promote their multiplication in host tissues
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enzymes that avoid immune responses and promote the multiplication in host tissues are called
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virulence factors or toxins
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each metabolic pathway is regulated by what?
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enzymes that catalyze the reactions
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Genetic control: repression
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when end products can stop the expression of genes that encode enzymes which are responsible for metabolic reactions
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genetic control: induction
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oppossite of repression. In this case synthesis of the mRNA that encodes the enzyme is turned on in the presence of the substrate for the enzyme
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energy from molecular motion
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thermal (heat)
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energy from the sun
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radiant (light)
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energy from electron flow
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electrical
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energy from a physical change in position
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mechanical
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energy from the reaction of the nucleus of the atom
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atomic
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energy present in the bonds of molecules
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chemical
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cells are too fragile for the use of what types of energy
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thermal or atomic energy
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what energy is most utilized by cells?
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chemical
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requires energy
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endergonic
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transfers energy for use in another reaction
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exergonic
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often endergonic and exergonic reactions are what? coupled or separate?
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coupled
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what are examples of a coenzyme?
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NAD and FAD
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what is a respiratory chain carrier?
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cytochromes (protein)
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ATP is a three part molecule...what are its parts?
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nitrogenous base, 5-carbon sugar (ribose), and chain of phosphates
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temporary energy repository
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ATP
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breaking of beta and alpha? phosphate bonds can provide free energy for other reactions is a characteristic of what?
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ATP
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what is the order of pathways of catabolism
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glycolysis, tricarboxylic acid cycle, respiratory chain (aerobic and anaerobic)
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partial oxidation of glucose
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glycolysis
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glycolysis requires the input of how many ATP molecules?
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2
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How many NADH molecules are produced in glycolysis?
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2
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NAD+ is reduced to what?
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NADH
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How many electrons does each NADH molecule carry?
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2 electrons
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What is the net ATP molecules produced during glycolysis?
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2
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How many pyruvate molecules are produced during glycolysis?
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2
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What is the net yield of electrons for glycolysis?
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4
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PMF
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proton motive force
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The electron transport chain is located where for eukaryotes?
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inner membrane of the mitochondria
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The ETC is located where for prokaryotes?
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located in the cell membrane which occasionally infolds to create a larger surface area for this process.
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what are the folds of the cell membrane called?
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mesosomes
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integration of the catabolic and anabolic pathways always occur
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biosynthesis-anabolism
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intermediates within what serve multiple purposes?
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glycolysis and TCA
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What is the final electron acceptor in anaerobic respiration?
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nitrate or nitrite
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what pathways does fermentation consist of?
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fermentation only
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In fermentation what must be done in the absence of oxygen?
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the NADH from glycolysis is used to reduce the pyruvate in order to recycle the NAD+.
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What is the final electron acceptor in fermentation?
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pyruvate and it can be converted to an alcohol or an acid depending on the microbe
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Why does fermentation occur instead of glycolysis?
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oxygen is absent and also the cell must metabolize larger amounts of glucose to produce equivalent ATP
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What are facultative anaerobes?
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fermentation in the absence of oxygen and respiration in the presence of oxygen
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What are strict fermenters?
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no respiration (yeast)
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What can fermentation produce?
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alcoholic fermentation, acidic fermentation, and mixed acid fermentation
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