Question: Most lipids have some what character?
About the article "Biochemistry", section "Lipids_1".

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The term lipid comprises a diverse range of molecules and to some exfor relatively water-insoluble or nonpolar compounds of biological origin, including waxes, fatty acids (including essential fatty acids), fatty-acid derived phospholipids, sphingolipids, glycolipids and terpenoids, such as retinoids and steroids.
Some lipids are linear aliphatic molecules, while others have ring structures.
Some are aromatic, while others are not.
Some are flexible, while others are rigid.
Most lipids have some polar character in addition to being largely nonpolar.
Generally, the bulk of their structure is nonpolar or hydrophobic ("water-fearing"), meaning that it does not interact well with polar solvents like water.
Another part of their structure is polar or hydrophilic ("water-loving") and will tend to associate with polar solvents like water.
This makes them amphiphilic molecules (having both hydrophobic and hydrophilic portions).
In the case of cholesterol, the polar group is a mere -OH (hydroxyl or alcohol).
Lipids in food include the oils of such grains as corn, soybean, from animal fats, and are parts of many foods such as milk, cheese, and meat.
They also act as vitamin carriers as well. 
The term lipid composes a diverse range of molecules and to some extent is a catchall for relatively water-insoluble or nonpolar compounds of biological origin, including waxes, fatty acids, fatty-acid derived phospholipids, sphingolipids, glycolipids, and terpenoids (e.g., retinoids and steroids).
Some lipids are linear aliphatic molecules, while others have ring structures.
Some are aromatic, while others are not.
Some are flexible, while others are rigid.
Most lipids have some polar character in addition to being largely nonpolar.
In general, the bulk of their structure is nonpolar or hydrophobic ("water-fearing"), meaning that it does not interact well with polar solvents like water.
Another part of their structure is polar or hydrophilic ("water-loving") and will tend to associate with polar solvents like water.
This makes them amphiphilic molecules (having both hydrophobic and hydrophilic portions).
In the case of cholesterol, the polar group is a mere -OH (hydroxyl or alcohol).
In the case of phospholipids, the polar groups are considerably larger and more polar, as described below.
Lipids are an integral part of our daily diet.
Most oils and milk products that we use for cooking and eating like butter, cheese, ghee etc., are composed of fats.
Vegetable oils are rich in various polyunsaturated fatty acids (PUFA).
Lipid-containing foods undergo digestion within the body and are broken into fatty acids and glycerol, which are the final degradation products of fats and lipids.
Driving forces for membrane Curvature.
Lipid Spontaneous Curvature.
Perhaps the most simple and intuitive driving force in membrane curvature is the natural spontaneous curvature exhibited by some lipids.
This is because, depending on their chemical structures, lipids tend to curve with a slight spontaneously negative or positive curvature.
Lipids such as DOPC (dioleoyl phosphatidyl choline), diacyl glycerol, dioleyl phosphatidylethanolamine (DOPE) and cholesterol exhibit a negative spontaneous curvature.
On the other hand, lipids with smaller acyl chain area to polar head group area ratio tend to curve positively, in other words they exhibit positive spontaneous curvature.
The table below lists experimentally determined spontaneous curvatures for different lipids in DOPE (dioleyl phosphatidyl ethanolamine).
The energy requirements to generate a cylinder shaped cell from an originally flat membrane can be expressed asFCyl =πxLxKb(1/R - 2JB)where L is the length of the cylinder, JB is the difference between the spontaneous curvature, Js, for the lipids in the inner and outer leaflet divided by two, and Kb is the bending modulus of the bilayer.
The radii of membrane cylinders that form in intracellular membrane-transport pathways are typically ~25–30 nm.
So, the spontaneous curvature necessary to generate such cylinders equals ~(1/50) nm–1.
As JB results from a difference in the spontaneous curvatures of the monolayers, an unusual membrane lipid composition wouldbe required to produce such curvature.
The lipids cholesterol, dioleoylphosphatidylethanolamine(DOPE)and diacylglycerol are characterized by strongly negative spontaneous curvatures (figure 1) and therefore have the potential to generate a large membrane curvature.
However, even for these lipids, the required JB can be reached only if they are extensively concentrated in the internal monolayer. 
Protein–lipid interaction is the influence of membrane proteins on the lipid physical state or vice versa.
The questions which are relevant to understanding of the structure and function of the membrane are: 1) Do intrinsic membrane proteins bind tightly to lipids, and what is the nature of the layer of lipids adjacent to the protein?
2) Do membrane proteins have long-range effects on the order or dynamics of membrane lipids?
3) How do the lipids influence the structure of function of membrane proteins?
4) How do peripheral membrane proteins which bind to the layer surface interact with lipids and influence their behavior? 
Lipids are a group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E, and K), monoglycerides, diglycerides, triglycerides, phospholipids, and others.
The main biological functions of lipids include storing energy, signaling, and acting as structural components of cell membranes.
Lipids have applications in the cosmetic and food industries as well as in nanotechnology.
Lipids may be broadly defined as hydrophobic or amphiphilic small molecules; the amphiphilic nature of some lipids allows them to form structures such as vesicles, liposomes, or membranes in an aqueous environment.
Biological lipids originate entirely or in part from two distinct types of biochemical subunits or "building-blocks": ketoacyl and isoprene groups.
Using this approach, lipids may be divided into eight categories: fatty acids, glycerolipids, glycerophospholipids, sphingolipids, saccharolipids, and polyketides (derived from condensation of ketoacyl subunits); and sterol lipids and prenol lipids (derived from condensation of isoprene subunits).
Although the term "lipid" is sometimes used as a synonym for fats, fats are a subgroup of lipids called triglycerides.
Lipids also encompass molecules such as fatty acids and their derivatives (including tri-, di-, monoglycerides, and phospholipids), as well as other sterol-containing metabolites such as cholesterol.
Although humans and other mammals use various biosynthetic pathways to both break down and synthesize lipids, some essential lipids cannot be made this way and must be obtained from the diet.