Biological Molecules - Organic Chemistry

The structure is D-ribose because it is a five-carbon aldose with the hydroxyl groups on carbons 2, 3, and 4 all on the right in the Fischer projection.

All of these statements are true. A carbohydrate is said to have a "D" conformation in its acyclic form when the alcohol group on the carbohydrate's top stereocenter is on the right side in a Fischer projection. Most carbohydrates that we deal with in organic chemistry are aldoses, which means that they contain an aldehyde. The anomeric carbon is the site of attachment from one monosaccharide to another, and can be used to create polysaccharides.

Stereochemistry from second to fifth carbon is R, S, S, R, which indicates D-galactose. The Haworth structure is a six-membered ring, so the molecule is in its pyranose form. The molecule has its anomeric hydroxyl group pointing down, so it's the alpha anomer.

Stereochemistry from second to fifth carbon is R, S, R, R, which indicates D-glucose. The Haworth structure is a five-membered ring, so the molecule is in its furanose form. The molecule has its anomeric hydroxyl group pointing down, so it's the alpha anomer.

The pictured structure represents arachidonic acid due to the 20-carbon carboxylic acid chain with characteristic unsaturated (double) bonds after carbons 5, 8, 11, and 14.

Fatty acids can be labeled numerically from 1-X, or they can be labeled in reverse starting with omega-1 as the terminal carbon.

Oleic acid is a fatty acid consisting of 18 carbon molecules and a single unsaturated (double) bond after carbon 9, as pictured.

A triglyceride consists of three fatty acid chains bound to a glycerol backbone via ester bonds, as shown by the pictured structure.

The reaction described is an esterification in which water is a product—as is characteristic of a condensation reaction—and in which an ester bond is formed to connect the fatty acid chain and the glycerol molecule.

This question is a little bit tricky. At first glance, we would jump to the conclusion that this molecule is a long hydrocarbon chain attached to a carboxylic acid and, therefore, a fatty acid. The premise is correct. However, our conclusion is false because, by convention, a fatty acid must contain a carbon chain of at least 12 carbons. The given formula does not match the description for a steroid or triacylglycerol. The correct answer is none of these.

The primary biological function of a fatty acid is to serve as a medium for the derivation of other important lipids such as waxes, triacylglycerols, phospholipids, and other necessary lipids.

A triacylglycerol is derived from the hydrolysis of glycerols and fatty acids. Triacylglycerols have hydrophobic hydrocarbon tails and hydrophilic heads (amphipathic). The hydrophobic tails dissolve into dirt/grease on the skin while the hydrophilic tails work with running water to suspend and remove the dissolved impurities.

The correct answer is the lipid, wax. Lipids can often be identified based on their structure alone. The general structure of wax is an ester with two long carbon chains on each end of the ester, as seen in this problem. Additionally, fatty acids can be identified simply as long carbon chains with a carboxylic acid on one end, while the general structure of steroids can be seen as four connected hydrocarbon rings.

The molecule's skeletal structure contains two isoprene (2-methylbutyl) units, and therefore the molecule is a monoterpene.

By definition, isomers are compounds that share the same molecular formula but have differing molecular structures. 1-butanol and 2-butanol share the same formula, but the hydroxyl group can be located on either the first or second carbon on the molecule, yielding two different structures that share the same molecular formula. The other answers have different molecular formulas and are thus not isomers.

By definition, resonance structures are multiple Lewis structures that depict the same molecular compound. The only difference pertains to the way in which electrons are shared by atoms in the molecule. Molecules are weighted averages of their most stable resonance contributors.

Alpha-pinene is a terpene, and is thus composed of isoprene units. A single isoprene unit has 5 carbon atoms. This molecule has 10 carbons, thus it contains 2 isoprene units.

This is cholic acid, a steroid. Steroids can be easily identified by their characteristic fused ring structures.

The boron in 2 is sp 3 hybridized because of its four substituents and the carbon in 4 is sp hybridized because of its connection to only the nitrogen with a single .