Review for Exam 3 - Enzymes Flashcards

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1
Q

Vmax

A
  • highest velocity of the enzyme (maximum rate of reaction)

- achieved when all the enzyme active sites are filled with substrate (i.e. saturated)

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2
Q

Km

A
  • substrate concentration at which the rate of the reaction is 1/2 its maximum (i.e. the [S] at which 1/2 the enzyme active sites are filled w/substrates
  • measurement of rate of reaction
  • affected by substrate concentration, pH, temp & ionic strength
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3
Q

cofactors

A

help activate enzymes

can be inorganic or organic

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4
Q

organic cofactors

A

coenzyme A
NAD+
FAD
NADP+

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5
Q

inorganic cofactors

A

Zn
Fe
Cu

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6
Q

regulation of enzyme activity:

competitive inhibitors

A
  • competes w/substrate for same active site on enzyme
  • a higher concentration of substrate can be added to overcome competition
  • Vmax is not altered, but Km increases
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7
Q

regulation of enzyme activity:

non-competitive inhibitor

A
  • bind to protein at some place other than active site, which changes the shape of the enzyme & makes it less active or inactive
  • adding more substrate does not overcome inhibition
  • Vmax decreases & Km remains the same (won’t happen as quickly; less effective)
    e. g. DDT
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8
Q

regulation of enzyme activity:

irreversible inhibitor

A

bind to site & make enzyme permanently inactive
e.g. penicillin binds to a bacterial cell wall synthesizing enzyme / cyanide binds to respiratory protein & irreversibly inactivates them

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9
Q

regulation of enzyme activity:
allosteric regulation
feedback regulation
chemical modification

A

allosteric - have active and inactive sites / complex enzymes
feedback -
chemical -

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10
Q

Factors that affect enzyme activity

A
temperature
pH
salt concentration
substrate concentration
co-factors
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11
Q

Examples of EXERGONIC reactions

A
-∆G
osmosis
respiration
ice melting
burning fossil fuels
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12
Q

Examples of ENDERGONIC reactions

A
\+∆G
photosynthesis
active transport
amino acid biosynthesis
ATP synthesis
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13
Q

examples of EXOTHERMIC reactions

A

–∆H
respiration

burning fossil fuels
burning methane

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14
Q

examples of ENDOTHERMIC reactions

A

+∆H
photosynthesis
melting ice

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15
Q

Keq equals ____?`

A

reactants

  • higher the #, more quickly reaction took place = spontaneous
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16
Q

energy coupling

A

use of an exergonic process to drive an endergonic one
ex. using ATP to phosphoylate glucose, which then combines w/fructose to make sucrose = exergonic rxn. W/o ATP, glucose + fructose = endergonic rxn.
ATP + H2O —> ADP + Pi + 7.3 kcal
(exergonic & exothermic)