Quiz - Lipids - 3 | Lipids

Organic Chemistry 3 - Quiz - Lipids - 3


Which component primarily determines the melting point of a given triglyceride molecule?

The degree of saturation of the fatty acids determines the melting point of a triglyceride. Saturated fatty acids, without double bonds, allow the triglycerides to pack more tightly and thus have a higher melting point. In contrast, unsaturated fatty acids with one or more double bonds cause kinks in the fatty acid chains, preventing tight packing and resulting in lower melting points.


Which of the following best describes the role of steroids in biological systems?

Steroids, which include hormones like testosterone and estrogen, function primarily as signaling molecules in the body. In addition, cholesterol – a type of steroid – plays a crucial role in the structure and fluidity of cell membranes.


What is the abbreviation commonly used to denote pyrophosphate?

Pyrophosphate is commonly abbreviated as OPP, representing the two phosphate groups linked by an oxygen atom.


What is the precursor molecule for the biosynthesis of terpenes?

Isopentenyl pyrophosphate (IPP) serves as the precursor molecule for the biosynthesis of terpenes, providing the building blocks for their synthesis.


What property of eicosanoids allows them to function as local signaling molecules (autacoids)?

Eicosanoids, which are derived from fatty acids, can easily traverse cell membranes due to their lipophilic nature, which allows them to function as autacoids – signaling molecules that act near their site of synthesis – without the need for long-distance transport.


What chemical feature is shared by all terpenes that contributes to their diverse roles in living organisms?

Terpenes are built up from isoprene units, a five-carbon building block that results in diverse molecular structures. This modular nature of terpenes contributes to their wide range of functions, from pigments and fragrances to vitamins and hormones.


Which of the following is not a type of lipid?

Polypeptides are not lipids; they are polymers composed of amino acids and are classified as proteins.


In the context of phospholipids, what is the consequence of having a kinked versus a straight fatty acid tail?

Kinked fatty acid tails, typically resulting from cis-double bonds in unsaturated fatty acids, create spaces in the lipid bilayer that make the membrane more fluid. This affects the flexibility and permeability of the cell membrane and its ability to host membrane proteins and signaling molecules.


Which carbon positions in the cholesterol molecule have methyl groups attached?

Cholesterol has methyl groups attached at carbon positions 10 and 13 in its tetracyclic ring structure.


What is the significance of steroids being precursors to both sex hormones and adrenal hormones?

Both sex hormones and adrenal hormones are derived from the cholesterol, a common steroid. This highlights the diverse functions of steroids in the body and their shared biosynthetic pathways, reflecting the complexity and interconnectivity of hormone regulation.