MCAT4eBioBiochem1LB.pdf - Bio/Biochem 1 High-Yield Science:...

BIO/BIOCHEM 1
High-Yield Science:
Enzyme Kinetics

12
Section I High-Yield Science
Bio/Biochem 1
ENZYME KINETICS
In this lesson, you’ll learn to:
·
Explain the significance of key aspects of the double-reciprocal Lineweaver–Burk format,
including axes, intercepts, units, and slopes
·
Identify V
max
and K
M
on both Michaelis–Menten and Lineweaver–Burk plots
·
Plot the effects of competitive inhibition on both graph types
Enzyme activity is often graphed using a Michaelis–Menten plot. However, enzyme activity may also
be graphed using an alternative format, the Lineweaver–Burk plot. HMG-CoA reductase is the rate-
limiting enzyme of cholesterol synthesis. Statins, such as atorvastatin (Lipitor), simvastatin (Zocor),
and rosuvastatin (Crestor) are routinely used to treat patients with high cholesterol because they are
competitive inhibitors of HMG-CoA reductase. How would the use of a statin affect the Lineweaver–
Burk plot of HMG-CoA reductase?
Michaelis–Menten Plot
Substrate Concentration [S]
Reaction Velocity
A Michaelis–Menten plot clearly shows the asymptotic behavior of a plot of an enzyme’s kinetics.
What is the plot’s basic shape? How does it display K
M
and V
max
?
Enzyme Kinetics are covered in:
Biochemistry, Chapter 2: Enzymes

13
Section I High-Yield Science
Bio/Biochem 1
Lineweaver–Burk Plot
(mM
–1
)
1
[S]
(s/μmol)
1 V
A Lineweaver–Burk plot shows the same information as a Michaelis–Menten plot. How does it display
K
M
and V
max
? What are the benefits of a Lineweaver–Burk plot, compared to a Michaelis–Menten plot?
Why does a competitive inhibitor increase an enzyme’s K
M
while leaving its V
max
unchanged?
A competitive inhibitor will have the effect of increasing the slope of a Lineweaver–Burk plot. Why?

205
LESSON 5.1
Science Passage Strategy
In this lesson, you’ll learn to:
·
Preview a science passage at a glance, determining
likely topics and difficulty
·
Identify the most question-relevant information in a
science passage
·
Create efficient and useful passage outlines
Science Topics:
·
Intermolecular Forces
·
Organic Chemistry Reaction Analysis
·
Translational Motion
MCAT STRATEGY—SCIENCE PASSAGES
SCAN
FOR STRUCTURE
Determine your “gut feeling” about the passage with a quick preview
READ
STRATEGICALLY
Read the passage, focusing your attention on the more test-worthy details
LABEL
EACH COMPONENT
Write down a short label or summary for each paragraph and figure as you read
REFLECT
ON YOUR OUTLINE
Make a full passage summary for yourself before moving to the questions
MCAT
Science
Skills
Scientific
Reasoning
and Problem
Solving
Experimental
and Research
Design
Data and
Statistical
Analysis
Science
Knowledge
MCAT
Expertise