Melting Point, Fatty Acids, and Lipids

Flashcards about Melting Point, Fatty Acids, and Lipids

Saturated Fatty Acids Packing

Saturated fatty acids pack in an orderly way leading to extensive favorable interactions.

Unsaturated Fatty Acids Packing

Unsaturated cis fatty acids pack less orderly due to the kink which leads to less-extensive favorable interactions.

Melting Point of Unsaturated Fatty Acids

Unsaturated cis fatty acids have a lower melting point because it takes less thermal energy to disrupt disordered packing.

Trans Fatty Acids Formation

Formed by partial dehydrogenation of unsaturated fatty acids to increase shelf life or stability at high temperature of oils used in cooking.

Packing and Melting Points of Trans Fatty Acids

Trans fatty acids can pack more regularly and show higher melting points than cis forms.

Health Risks of Trans Fats

Consuming trans fats increases the risk of cardiovascular disease. Avoid deep frying in partially hydrogenated vegetable oils.

Triacylglycerols

The majority of fatty acids are found in the form of triacylglycerols; solid ones are called fats and liquid ones are called oils.

Function of Triacylglycerols

The primary storage form of lipids (body fat).

Properties of Triacylglycerols

Less soluble in water than fatty acids due to the esterification of the carboxylate group; less dense than water, causing fats and oils to float.

Advantages of Fats over Polysaccharides

Fatty acids carry more energy per carbon because they are more reduced, and they carry less water per gram because they are nonpolar.

Glucose and Glycogen Function

For short-term energy needs and quick delivery.

Fats Function

For long-term (months) energy needs, good storage, and slow delivery.

Waxes

Esters of long-chain saturated and unsaturated fatty acids with long-chain alcohols; insoluble and have high melting points.

Functions of Waxes

Storage of metabolic fuel in plankton, protection and pliability for hair and skin in vertebrates, waterproofing of feathers in birds, and protection from evaporation in tropical plants and ivy.

Structural Lipids in Membranes

Contain polar head groups and nonpolar tails (usually attached fatty acids).

Diversification of Structural Lipids

Modifying a different backbone, changing the fatty acids, or modifying the head groups.

Head Group Properties of Lipids

The properties of head groups determine the surface properties of membranes; different organisms and tissues have different membrane lipid head group compositions.

Amphipathic Lipids

Lipids in membranes must have both hydrophilic and hydrophobic regions.

Glycerophospholipids Definition

A type of membrane lipid where the hydrophilic component is a phosphate group and it consists of two fatty acids attached to the first two carbons of glycerol via an ester linkage.

Galactolipids and Sulfa lipids

Lipids in plant cells that contain 1-2 galactose residues connected by a glycosidic linkage to C3 of the sugar

Archael tetra-ether-lipids

Lipid spans entire length of membrane with hydrophilic head groups on ends. Lipids are twice the length of the normal phospholipids found in eukaryotic cells.

Sphingolipids

Membrane lipids that contain no glycerol

Sterols

Lipids containing four fused carbon rings

Glycerophospholipids Composition

Primary constituents of cell membranes where two fatty acids form ester linkages with the first and second hydroxyl groups of L-glycerol-3-phosphate.

Common Fatty Acid Location

Unsaturated fatty acids are commonly found connected to C2 of glycerol-3-phosphate.

Head Groups of Glycerophospholipids

The highly polar phosphate group may be further esterified by an alcohol; substituent groups are called head groups.

Phosphatidylcholine

The major component of most eukaryotic cell membranes.

Sphingolipids Structure

The backbone is a long-chain amino alcohol sphingosine and a fatty acid is joined via an amide linkage.

Glycosphingolipids Location

The sugar-containing glycosphingolipids are found largely in the outer face of plasma membranes.