Talk:Lipid

Lipids are fatty acid esters... and cholesterol as lipid

Most of what I have seen counts cholesterol lipids, and this page in fact does so when it lists the hydrophobic and hydrophilic groups, but cholesterol is definitely not a fatty acid ester.

Jedi Dan, Uhm actually cholesterol molecules are not lipids. They are actually a series of circular hydrocarbon molecules, each bonded together. I cant remember exactly what cholesterol looks like, but cholesterol and the steroid hormones derived from it typically have hydroxyl (OH), ketone/aldehyde (C=O) and methyl groups on them.

What he said is correct, assuming R1' to be a hydrocarbon chain (except the last carbon atom) and R2' to be a glycerol molecule, you could show it to be R1'-CO-O-R2' where the CO is a double bond. Check out the links below, they would probably explain better than I can in text.

Read more about steroid hormones/cholesterol at http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/Cholesterol.html

Read more about triglycerides at http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/F/Fats.html

• I too have generally thought cholesterol and steroids as not being "lipids". However, the following passage appears in General Chemistry Online!: "lipid. A diverse group of organic molecules that contain long hydrocarbon chains or rings and are hydrophobic. Examples are fats, oils, waxes, and steroids." Likewise the Drug Discovery & Development Glossary states that a lipid is "an oil-soluble molecule such as a fatty acid or steroid." If on the other hand one looks at the IUPAC Nomenclature Recommendations, lipids and steroids are classed differently. Under IUPAC Nomenclature, lipids are a class of molecules that includes fatty acids, neutral fats, long-chain alcohols, long-chain bases, phospholipids, glycolipids and neuraminic acid. Therefore, I'd say that "lipids include steroids when the term (lipid) is used in a colloquial sense; however, from an organic chemistry nomenclature point of view, steroids are formally excluded from the lipid-class of molecules." Courtland 01:52, 2005 Mar 8 (UTC)
• Here's a more concise view which is part of the IUPAC Glossary of Class Names, the Lipid entry, which goes into specifics of what is included in the class: http://www.chem.qmul.ac.uk/iupac/class/lipid.html. Now this page says that the term lipid is "a loosely defined term for substances of biological origin that are soluble in nonpolar solvents. They consist of saponifiable lipids, such as glycerides (fats and oils) and phospholipids, as well as nonsaponifiable lipids, principally steroids." Therefore, steroids are lipids afterall and their separation in the IUPAC nomenclature does not indicate they are unrelated. Courtland 02:03, 2005 Mar 8 (UTC)

Sometimes categories can be incompletely congruent in different contexts. For example, cholesterol is always considered a lipid in a medical context, and this would be a common reason for a reader to look at this article. We need a section on cholesterol and other sterols explaining how they differ from triglycerides and in what contexts they are or are not considered lipids. alteripse 14:07, 24 December 2005 (UTC)

unpolar

I have never seen this before - should be non-polar (or nonpolar)? --Anon

Thanks for catching that. --maveric149

Amphipathic? This makes no sense

You mean Amphiphilic right? I hope you dont mind if I make a few minor chances to make it more technically accurate. Jedi Dan

Lipids are in the news this week,

and I thought this page should update to reflect... but don't have the time to do it now.

A quote

In the LIPID MAPS classification scheme, lipids are divided into eight primary categories: fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, sterol lipids, prenol lipids, saccharolipids, and polyketides. These categories are based on the functional backbone of the lipid molecule from a chemical standpoint. The categories are further subdivided into classes and subclasses to handle the existing and emerging arrays of lipid structures.

Source: [1]

I'll check back later, but perhaps someone with more biology than I can start to take a whack at that. JRice 21:28, 13 May 2005 (UTC)

Question?

what is the primary physiological function of lipids: a. provide absorbtion of fat soluble vitamins b. conserve heat c. provide material for synthesis of hormones d. supply energy ???

How about e. all of the above? alteripse 03:37, 10 January 2006 (UTC)