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Ch. 8

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Biochemistry
Amy Arce
Quiz por Amy Arce, atualizado more than 1 year ago
Amy Arce
Criado por Amy Arce mais de 8 anos atrás
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Resumo de Recurso

Questão 1

Questão
What are Enzymes?
Responda
  • Protein Catalysts that can slow the rate of a reaction
  • Protein Catalysts that can accelerate the rate of a reaction
  • Tightly bound coenzymes

Questão 2

Questão
A reaction such as the addition of a molecule of water to carbon dioxide requires an enzyme, carbonic anhydrase, in red blood cells. What are some functions of this enzyme?
Responda
  • Operates in animal cells, plants cells, and in the environment to stabilize carbon dioxide concentrations
  • The conversion from carbon dioxide to bicarbonate, would be extremely fast without this enzyme
  • The conversion from carbon dioxide to bicarbonate, would be extremely slow, without this enzyme
  • Carbonic anhydrase adjusts the acidity of the chemical environment to prevent damage to the body

Questão 3

Questão
Reactants in enzyme-catalyzed reactions are called [blank_start]substrates[blank_end]
Responda
  • substrates
  • apoenzyme
  • coenzyme

Questão 4

Questão
What enzyme catalyzes the hydrolysis of peptide bonds and ester bonds?
Responda
  • Proteolytic Enzymes
  • Lytic Enzymes
  • Carbonic anhydrase

Questão 5

Questão
Enzymes can display a high degree of specificity
Responda
  • True
  • False

Questão 6

Questão
Specificity of enzymes is due to the precise interaction of the enzyme and its cofactor
Responda
  • True
  • False

Questão 7

Questão
What are functions of Trypsin ?
Responda
  • Protein digesting enzyme
  • Present in pancreatic juices secreted into your small intestine during a meal
  • Pancreas secretes trypsin as an inactive proenzyme called trypsinogen
  • Helps break down food protiens

Questão 8

Questão
Proteolytic enzymes trypsin and papain have different degrees of specificity
Responda
  • True
  • False

Questão 9

Questão
Enzymes do not require cofactors for activity
Responda
  • True
  • False

Questão 10

Questão
Cofactors are
Responda
  • Large molecules that some enzymes require for activity
  • Small molecules that some enzymes require for activity

Questão 11

Questão
The two main classes of cofactors are
Responda
  • Coenzymes and metals
  • Coenzymes and acids
  • Metals and acids

Questão 12

Questão
Tightly bound coenzymes are called
Responda
  • Apoenzyme
  • bioenzyme
  • prosthetic groups
  • Substrates

Questão 13

Questão
An enzyme with its cofactor is an apoenzyme, without the cofactor, the enzyme is called an holoenzyme
Responda
  • True
  • False

Questão 14

Questão
Specific Enzymes play key roles in the conversion of light energy and carbon oxidation energy into ATP
Responda
  • True
  • False

Questão 15

Questão
Using ATP, enzymes can generate
Responda
  • Red blood cells
  • Chemical gradients
  • Electrical gradients

Questão 16

Questão
The free- energy change provides information about the spontaneity but not the rate of reaction
Responda
  • True
  • False

Questão 17

Questão
Exogeneric reactions are
Responda
  • A reaction that will occur without the input of energy, or spontaneously, lf delta G is negative
  • A reaction that will occur without the input of energy, or spontaneously, if delta G is positive
  • A reaction that will occur with the input of energy, or nonspontaneous, if delta G is positive
  • A reaction that will occur without the input of energy, or nonspontaneous, if delta G is positive

Questão 18

Questão
Exergonic reactions refers to
Responda
  • a reaction where energy is taken up
  • a reaction where energy is released
  • Delta G is negative
  • Delta G is positive
  • Do require energy to proceed occur nonspontaneously
  • Do not require energy to proceed, occur spontaneously

Questão 19

Questão
Endergonic reaction refers to
Responda
  • Energy being absorbed
  • Energy being released
  • Delta G is positive
  • Delta G is negative
  • Nonspontaneous reaction
  • Spontaneous reaction

Questão 20

Questão
The delta G reaction depends only on the free energy difference between reactants and products and is independent of how the reaction occurs
Responda
  • True
  • False

Questão 21

Questão
The delta G, of a reaction provides information about the rate of the reaction
Responda
  • True
  • False

Questão 22

Questão
Enzymes alter only the reaction rate and not the reaction equilibrium
Responda
  • True
  • False

Questão 23

Questão
The energy required to form the transition state from the substrate is called the
Responda
  • Activation energy
  • Catalyst
  • Endergonic
  • Exergonic

Questão 24

Questão
A chemical reaction proceeds through a [blank_start]transition state[blank_end], a molecular form that is no longer substrate but not yet product
Responda
  • transition state

Questão 25

Questão
What is the first step in the enzymatic catalysis process?
Responda
  • The formation of an enzyme substrate complex
  • The formation of an enzyme product complex
  • The formation of an enzyme reactant complex

Questão 26

Questão
Enzymes bring substrates together to form an [blank_start]enzyme-substrate[blank_end] complex on a particular region of the enzyme called the [blank_start]active site[blank_end]
Responda
  • enzyme-substrate
  • enzyme-product
  • active site
  • transition site

Questão 27

Questão
Enzymes function by lowering the activation site
Responda
  • True
  • False

Questão 28

Questão
The interaction between enzyme and substrate was established by
Responda
  • The observation that a fixed amount of enzyme displays a maximal velocity
  • The observation that a fixed amount of enzyme displays a minimal velocity

Questão 29

Questão
The maximal rate of catalysis, Vmax occurs when all of the enzyme is bound to substrate
Responda
  • True
  • False

Questão 30

Questão
Active sites of enzymes have common features such as
Responda
  • Active site is a 3 dimensional cleft or crevice created by amino acids from different parts of the primary structure
  • Active sites constitutes a small portion of the enzyme volume
  • The interaction of the enzyme and substrate at the active sites involves multiple strong interactions
  • Enzyme specificity depends on molecular architecture at the active site
  • Active sites create unique microenvironments

Questão 31

Questão
The enzyme changes shape upon substrate binding, a phenomenon called [blank_start]induced fit[blank_end]
Responda
  • induced fit

Questão 32

Questão
Binding energy is
Responda
  • Free energy released upon interaction of enzyme and substrate
  • greatest when the enzyme interacts with the transition state
  • Free energy released upon interaction of enzyme and product
  • greatest when the enzyme interacts with the active state

Questão 33

Questão
Enzymes do not interact with their substrates like a lock and key
Responda
  • True
  • False

Questão 34

Questão
The Michaelis constant equal to the substrate concentration at which reaction rate is half its maximal value
Responda
  • True
  • False

Questão 35

Questão
[blank_start]Alcohol[blank_end] dehydrogenase converts [blank_start]ethanol[blank_end] into [blank_start]acetaldehyde[blank_end]
Responda
  • Alcohol
  • Aldehyde
  • ethanol
  • acetaldehyde
  • acetaldehyde
  • acetate

Questão 36

Questão
[blank_start]Aldehyde[blank_end] dehydrogenase converts [blank_start]acetaldehyde[blank_end] to [blank_start]acetate[blank_end]
Responda
  • Aldehyde
  • Alcohol
  • acetaldehyde
  • ethanol
  • acetate
  • acetaldehyde

Questão 37

Questão
What two enzymes play a key role in the metabolism of alcohol
Responda
  • Alcohol dehydrogenase and Aldehyde dehydrogenase
  • Alcohol dehydrogenase and Acetaldehyde dehydrogenase
  • Aldehyde dehydrogenase and Acetaldehyde dehydrogenase

Questão 38

Questão
What are the two different acetaldehyde dehydrogenase in most people ?
Responda
  • Low km in mitochondria
  • High km in cytoplasm
  • Low km in cytoplasm
  • High km in mitochondria

Questão 39

Questão
Kcat, is the turnover number of the enzyme,
Responda
  • which is the number of substrate molecules converted into product per second
  • which is the number of reactant molecules converted into product per second

Questão 40

Questão
Irreversible enzyme inhibitors bind
Responda
  • covalently or noncovalently to the enzyme, but with a negligible dissociation constant
  • covalently to the enzyme, but with a negligible dissociation constant
  • noncovalently to the enzyme, but with a negligible dissociation constant

Questão 41

Questão
Reversible inhibition is characterized
Responda
  • by slow dissociation of the enzyme inhibitor complex
  • by rapid dissociation of the enzyme inhibitor complex

Questão 42

Questão
Name three common types of reversible inhibition
Responda
  • Competitive inhibition
  • Uncompetitive inhibition
  • Noncompetitive inhibition
  • None of the above

Questão 43

Questão
Competitive inhibition
Responda
  • The inhibitor is structurally similar to the substrate and can bind to the active site, preventing the actual substrate from binding
  • The inhibitor binds only to the enzyme substrate complex in what is essentially substrate dependent inhibition
  • The inhibitor binds either the enzyme or enzyme substrate complex

Questão 44

Questão
Uncompetitive inhibition is essentially substrate dependent inhibition
Responda
  • True
  • False

Questão 45

Questão
Noncompetitive inhibition
Responda
  • Binds either the enzyme or enzyme substrate complex
  • Substrate dependent inhibition
  • Prevents the actual substrate from binding

Questão 46

Questão
Penicillin
Responda
  • is an antibiotic that consist of a thiazolidine ring fused to a reactive β-lactam ring
  • inhibits the formation of cell walls in certain bacteria such as S. aureus.
  • binds to the transpeptidase because it resembles the substrate.
  • participates in its own inhibition, penicillin is a suicide inhibitor

Questão 47

Questão
The cell wall of S. aureus is constructed from the molecule peptidoglycan, which is a linear polysaccharide chain cross-linked by short peptides.
Responda
  • True
  • False

Questão 48

Questão
What catalyzes the peptide cross links
Responda
  • peptidoglycan
  • Glycopeptide transpeptidase
  • Penicillin

Questão 49

Questão
The transpeptidase reaction proceeds through an acyl-enzyme terminator.
Responda
  • True
  • False

Questão 50

Questão
When penicillin binds to the transpeptidase,
Responda
  • a serine residue at the active site attacks the carbonyl carbon of the lactam ring as if penicillin were a substrate.
  • a serine residue at the active site attacks the carbonyl carbon of the lactam ring as if penicillin were a product

Questão 51

Questão
Penicilloyl-serine derivative is inactive and very unstable
Responda
  • True
  • False

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