1. Committed step in cholesterol biosynthesis
CH2C- OH
CH2C-SCoA O
-OOC
CH3
2 NADPH + 2H+
HMG-CoA-reductase ER
2 NADP + CoA
lovastatin
CH2C- OH
CH2C- OH O
-OOC
CH3
mevalonate

2. Biosynthesis of cholesterol from mevalonate C10 C15 C30 squalene OH O
-OOC
CH2 C-
CH2 C- OH
mevalonate
CH3
3 ATP
3 ADP + Pi + CO2
CH C-
CH2 C- O-P-O-PO3-2 O
CH3
3-isopentenylpyrophosphate
C10
C15
C30
squalene

3. N.B. You are not required to know the structures of these steroids.
You only need to know the structure of cholesterol.
Adapted from Berg, Tymoczko and Stryer
Biochemistry 5th ed.