20 Questions
Which step in cholesterol synthesis is catalyzed by the rate-limiting enzyme HMG CoA reductase?
Step 1
How many acetyl CoA molecules are needed to make squalene in cholesterol synthesis?
3 acetyl CoA
Which enzyme is the main regulatory step of cholesterol synthesis?
HMG CoA reductase
Which molecule promotes the de-phosphorylation and activation of HMG CoA reductase?
Insulin
Which molecule promotes the phosphorylation and inhibition of HMG CoA reductase?
Glucagon
High intracellular levels of cholesterol (increase/decrease) the transcription of HMG CoA reductase gene.
Decrease
What is the name of the enzyme that catalyzes the conversion of mevalonate into activated isoprenes in cholesterol synthesis?
Isopentenyl pyrophosphate
What is the final step in cholesterol synthesis, where linear squalene is converted into the cyclic structure of cholesterol?
Step 4
Which molecule is immediately removed during the conversion of mevalonate into activated isoprenes in cholesterol synthesis?
Isopentenyl pyrophosphate
What is the name of the enzyme that catalyzes the condensation of 6 activated isoprene units to form squalene in cholesterol synthesis?
Farnesyl pyrophosphate
Which class of lipids is cholesterol classified as?
Steroid
Which organs of the body contribute most significantly to cholesterol synthesis?
Liver and kidney
Where does cholesterol synthesis occur inside the cell?
Endoplasmic reticulum
Which enzyme plays a key regulatory role in cholesterol synthesis?
HMG CoA reductase
What are the basic steps of cholesterol synthesis?
Condensation of acetyl CoA into mevalonate, formation of isopentenyl pyrophosphate, creation of squalene
What is the role of HMG CoA reductase in cholesterol synthesis?
Condensation of acetyl CoA into mevalonate
What inhibits HMG CoA reductase in cholesterol synthesis?
High intracellular levels of cholesterol
Which class of lipids are based on fatty acid structure?
Phospholipids
What is the structural unit in isoprenoids?
Isopentenyl pyrophosphate
What is the term for steroids with a hydroxy group at C3?
Sterols
Test your knowledge on cholesterol synthesis, its classification, and its role in the body with this quiz!
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