18 Questions
What is the definition of amphipathic lipids?
Molecules containing both hydrophobic and hydrophilic groups.
Give an example of an amphipathic lipid.
Phospholipids
How do amphipathic lipids orient themselves in water?
Polar heads towards aqueous phase, non-polar tails opposite.
What is the importance of micelle formation in lipid digestion?
Facilitates lipid digestion and absorption.
Name two other sterols present in plant cells besides ergosterol.
Stigmasterol and βsitosterol
What is the structure of ergosterol?
Not provided in the text.
What is the role of cholesterol in the plasma membranes?
Cholesterol is a structural component of plasma membranes and is higher in the membranes of subcellular organelles.
Why is cholesterol considered a poor conductor of heat and electricity?
Cholesterol is a poor conductor of heat and electricity due to its high dielectric constant.
What are the functions of cholesterol besides being a structural component of membranes?
Cholesterol plays a role in the synthesis of bile acids, hormones (sex and cortical), and vitamin D.
Where does ergosterol occur and what is its importance?
Ergosterol occurs in plants and is a structural constituent of membranes in yeast and fungi. It is also an important precursor for vitamin D.
What is the significance of ergosterol in the context of vitamin D synthesis?
Ergosterol is an important precursor for vitamin D synthesis, especially when exposed to light.
How does the structure of ergosterol differ from cholesterol?
Ergosterol is primarily found in plants, yeast, and fungi, while cholesterol is a component of animal cells.
What is the chemical formula of cholesterol?
C27H46O
What is the structure of cholesterol?
Cholesterol has one hydroxyl group at C3 and a double bond between C5 and C6.
What does the term 'sterol' refer to in the context of steroids?
If the steroid contains one or more hydroxyl groups, it is commonly known as sterol.
Why is cholesterol considered weakly amphiphilic?
Due to the presence of an -OH group.
What is the significance of the methyl side chains attached to carbons 10 and 13 in steroids?
The methyl side chains at carbons 10 and 13 are shown as single bonds.
Where is cholesterol exclusively found?
Cholesterol is exclusively found in animals.
Test your knowledge on the structure, properties, and reactions of cholesterol. Learn about the aliphatic side chain, methyl groups, solubility, and identification tests like Salkowski's test and Liebermann-Burch reaction.
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