Chapter #11: Lipids Flashcards
(65 cards)
True or False: The only function of lipids is as a structural component of the cell membrane
False
What are lipids?
A class of hydrocarbon-containing organic compounds, categorized by the fact that they are soluble in nonpolar solvents (such as ether and chloroform) and are relatively insoluble in water.
Why do lipids have their properties?
Lipid molecules have these properties because they are hydrophobic in nature
What are lipids used for?
Lipids are used for energy storage, serve as structural components of cell membranes, and constitute important signaling molecules.
What is the difference between fats and lipids?
The term lipid is often used as a synonym for fat, but fats are actually a subgroup of lipids called triglycerides.
What are fatty acids?
Long hydrocarbon chains (fatty) with carboxylic acids on one end (acid)
What are triglycerides (fats)?
the storage form of lipids. They are comprised of three (tri) fatty acids attached to a molecule of glycerol (glyceride).
What are steroids?
Lipids characterized by a carbon skeleton with four fused rings. Includes compounds such as cholesterol, testosterone, progesterone, and estrogens.
What are phospholipids?
A class of lipids formed from four components: fatty acids, a negatively-charged phosphate group, an alcohol, and a backbone.
When are fatty acids saturated?
If composed of one single bonds, they are called saturated fatty acids
When are fatty acids unsaturated?
they are named unsaturated fatty acids (one or more double/triple bonds)
What is the structure of fatty acids?
Fatty acids are simply long hydrocarbon chains with carboxylic acid groups
What are degrees of unsaturation?
double bonds
What is the main role of fatty acids?
Their main role is as fuels and structural element for membranes
What is the systematic name of the fatty acid derived from?
The systematic name of the fatty acid is derived from the name of the parent hydrocarbon, in which the final e is removed and replaced with oic
How are unsaturations indicated in Fatty Acids?
Unsaturation is also indicated in the name:
1 double bond:
C18 Octadecene becomes octadecenoic acid
2 double bonds
octadecadienoic acid
3 double bonds
octadecatrienoic acid
How are carbons named in fatty acids?
The number of total carbons is followed by a colon, and then the number of double bonds is indicated.
18:1 = 18 carbons, 1 double bond
Where does the numbering of carbon atoms start in fatty acid nomenclature?
The numbering of the carbon atoms starts at the carboxyl terminus.
What are the positions of the double bonds in fatty acids indicated by?
The position of double bonds is indicated by a and a superscript number to indicate the number of the first carbon in the bond.
C18:1 between C9 and C10 : Δ 9-octadecenoic acid
How are carbons 2 and 3 referred to as in fatty acid nomenclature?
Carbons 2 and 3 are often referred to as α and β, and the distal carbon is ω (omega), the last letter of the Greek alphabet (numbering can also start from the ω carbon, but is indicated as such like in ω-3 fatty acids)
How many carbon atoms are usually in fatty acids?
They usually contain an even number of carbon atoms (14-24C) due to their biosynthesis.
Which carbon numbers are the most common in fatty acids?
The 16- and 18-carbon fatty acids are the most common (palmitate and stearate, respectively).
How do chain length and degree of unsaturation affect the fluidity of fatty acids?
Less unsaturation and longer chain length = higher melting point and less fluidity
ex: butter (palmitic), palm oil (oleic)
More unsaturation and shorter chain length = lower melting point and more fluidity
ex: olive oil (oleic), soybeans (linoleic)
What does membrane fluidity depend on?
Membrane fluidity depends on the length and saturation of fatty acid chains:
Saturated, long fatty acids favor the rigid state due to strong interactions.
Unsaturated or shorter fatty acids interfere with packing (kinks in hydrocarbon chain) or have weaker interactions (less interacting surface).
