Introduction to Lipids and Isomers

Flashcards based on the lecture transcript covering lipids, fatty acids, triglycerides, ester linkages, geometric isomers, enantiomers, and thalidomide.

What major class of biomolecules was covered right before lipids in this lecture?

Carbohydrates

What are the four major classes of biomolecules listed in the lecture?

Carbohydrates, DNA, lipids, and protein

What general property do all lipids share regarding water solubility?

They are hydrophobic

What main monomer structure is found in virtually all lipids?

A fatty acid

Where is the high energy storage located within a fatty acid molecule?

Between the carbon and hydrogen bonds

What chemical process joins fatty acids to glycerol to form lipids?

A condensation dehydration synthesis reaction

What specific type of bond linkage connects a fatty acid to glycerol?

An ester linkage

What is a saturated fatty acid?

A fatty acid where every carbon is occupied with single bonds to hydrogen, containing no double bonds between carbons

Why are saturated fats solid at room temperature while unsaturated fats are liquid?

Saturated fats have straight molecules that pack tightly together, whereas unsaturated fats have double bonds that form kinks, preventing tight packing

Why does the instructor emphasize that lipids do not form true polymers?

Lipids are not repeating chains of monomers joined end-to-end; three fatty acids bind individually to separate points on one glycerol molecule

What does the term amphipathic mean?

Describing a molecule that has both polar and nonpolar regions

Why is a free fatty acid considered amphipathic before it bonds to glycerol?

It contains a polar carboxyl acid group on one end and a nonpolar fatty chain on the other

What defines a geometric isomer?

An isomer with the same molecular formula that has a difference in the position of functional groups or atoms across a carbon-carbon double bond

What is the difference between a cis fat and a trans fat arrangement?

In a cis fat arrangement, identical atoms or groups are on the same side of the double bond, whereas in a trans arrangement, they are on opposite sides

Why can cis-trans geometric isomers exist around a carbon-carbon double bond but not a single bond?

Single bonds allow free rotation of attached atoms, whereas double bonds prevent free rotation and lock atoms into position

What is a chiral molecule or enantiomer?

A stereoisomer that consists of non-superimposable left-handed and right-handed mirror images around a central chiral carbon bonded to four different groups

How did the $R$ enantiomer and $S$ enantiomer of thalidomide differ in their biological effects?

The $R$ enantiomer helped cure morning sickness, whereas the $S$ enantiomer caused severe birth defects

Why could isolating a $100\%$ pure $R$ enantiomer of thalidomide still not make it safe during pregnancy?

Because the $R$ enantiomer can convert into the $S$ enantiomer inside the human body

For what medical condition was thalidomide approved by the FDA in 1998?

Complications from Hansen's disease (leprosy)

What alternative name in chemistry is used for Van der Waals interactions?

London dispersion forces