BCH 361 EXAM 2 QUESTIONS WITH VERIFIED
ANSWERS
What is the Michaelis-Menten equation? - Answers -
Vmax definition - Answers - Vmax = maximum velocity possible given the enzyme
concentration
all enzymes occupied
Km definition? - Answers - how much substrate we need for V0 to reach 1/2 of the
Vmax
half of all enzymes are occupied
known as Michaelis constant
[E]t definition? - Answers - total enzyme concentration
if E total increases, Vmax increase (direct relationship, same amount)
V0 (V not) definition? - Answers - initial rate of the reaction
V zero means a velocity of zero, because if there is no substrate, so there is no speed
Y variable on graph
V0 becomes Vmax when? - Answers - substrate concentration is very high
Bigger Km means? - Answers - enzyme-substrate interaction is weak, enzyme not
efficient*
not as steep of a slope, takes longer to reach Vmax
the enzyme thats it slower will have a bigger Km*
Lower Km means? - Answers - enzyme-substrate interaction is strong, enzyme is
efficient, steep slope
do not need a lot of substrate to form enzyme-substrate complex
What is the value of V0 when substrate concentration is equal to KM? - Answers - 1/2 of
Vmax
, [S] = Km
When [S] = Km? - Answers - half of the enzymes have their active sites filled
If [S] << KM? - Answers - look on left side of Km
if substrate concentration is less than Km, enzyme active sites are less filled
V0 is sensitive to changes in substrate concentration
If [S] >> KM? - Answers - look on the right side of Km
substrate concentration greater than Km, enzyme active sites are more filled + more
saturated
V0 does not change with substrate concentration because you're close to being at
Vmax
What is the Lineweaver-Burk plot? - Answers - accurately measures the value of Vmax
and Km
take the inverse (*double reciprocal plot) of all variables from Michaelis graph
*on michaelis graph, Vo is the Y axis, but on lineweaver it is 1/Vo
*on michaelis graph, [S] is the x axis, but on lineweaver it is 1/[S]
Slope of Lineweaver-burk plot? - Answers - Slope = Km/Vmax
Y-intercept of Lineweaver-burk plot? - Answers - Y-int = 1/Vmax
X-intercept of Lineweaver-burk plot? - Answers - X-int = -1/Km
Calculations for plotting - Answers - Vmax = 1/(Y-intercept)
KM = -1/(X-intercept)
Vmax = KM/slope = -1/(X-intercept*slope)
KM = Vmax*slope = slope/Y-intercept
How will the Lineweaver-Burk plot change if we change KM? Vmax? - Answers - if Km
goes up or down, the X intercept changes
if Vmax goes up or down, the Y intercept changes
ANSWERS
What is the Michaelis-Menten equation? - Answers -
Vmax definition - Answers - Vmax = maximum velocity possible given the enzyme
concentration
all enzymes occupied
Km definition? - Answers - how much substrate we need for V0 to reach 1/2 of the
Vmax
half of all enzymes are occupied
known as Michaelis constant
[E]t definition? - Answers - total enzyme concentration
if E total increases, Vmax increase (direct relationship, same amount)
V0 (V not) definition? - Answers - initial rate of the reaction
V zero means a velocity of zero, because if there is no substrate, so there is no speed
Y variable on graph
V0 becomes Vmax when? - Answers - substrate concentration is very high
Bigger Km means? - Answers - enzyme-substrate interaction is weak, enzyme not
efficient*
not as steep of a slope, takes longer to reach Vmax
the enzyme thats it slower will have a bigger Km*
Lower Km means? - Answers - enzyme-substrate interaction is strong, enzyme is
efficient, steep slope
do not need a lot of substrate to form enzyme-substrate complex
What is the value of V0 when substrate concentration is equal to KM? - Answers - 1/2 of
Vmax
, [S] = Km
When [S] = Km? - Answers - half of the enzymes have their active sites filled
If [S] << KM? - Answers - look on left side of Km
if substrate concentration is less than Km, enzyme active sites are less filled
V0 is sensitive to changes in substrate concentration
If [S] >> KM? - Answers - look on the right side of Km
substrate concentration greater than Km, enzyme active sites are more filled + more
saturated
V0 does not change with substrate concentration because you're close to being at
Vmax
What is the Lineweaver-Burk plot? - Answers - accurately measures the value of Vmax
and Km
take the inverse (*double reciprocal plot) of all variables from Michaelis graph
*on michaelis graph, Vo is the Y axis, but on lineweaver it is 1/Vo
*on michaelis graph, [S] is the x axis, but on lineweaver it is 1/[S]
Slope of Lineweaver-burk plot? - Answers - Slope = Km/Vmax
Y-intercept of Lineweaver-burk plot? - Answers - Y-int = 1/Vmax
X-intercept of Lineweaver-burk plot? - Answers - X-int = -1/Km
Calculations for plotting - Answers - Vmax = 1/(Y-intercept)
KM = -1/(X-intercept)
Vmax = KM/slope = -1/(X-intercept*slope)
KM = Vmax*slope = slope/Y-intercept
How will the Lineweaver-Burk plot change if we change KM? Vmax? - Answers - if Km
goes up or down, the X intercept changes
if Vmax goes up or down, the Y intercept changes
