Lipid

Structures of some common lipids. At the top are cholesterol and oleic acid. The middle structure is a triglyceride composed of oleoyl, stearoyl, and palmitoyl chains attached to a glycerol backbone. At the bottom is the common phospholipid phosphatidylcholine.
I2 - Prostacyclin (an example of a prostaglandin, an eicosanoid fatty acid)
LTB4 (an example of a leukotriene, an eicosanoid fatty acid)
Example of an unsaturated fat triglyceride (C55H98O6). Left part: glycerol; right part, from top to bottom: palmitic acid, oleic acid, alpha-linolenic acid.
Phosphatidylethanolamine
Sphingomyelin
Chemical structure of cholesterol.
Prenol lipid (2E-geraniol)
Structure of the saccharolipid Kdo2-lipid A. Glucosamine residues in blue, Kdo residues in red, acyl chains in black and phosphate groups in green.
Self-organization of phospholipids: a spherical liposome, a micelle, and a lipid bilayer.

Macro biomolecule that is soluble in nonpolar solvents.

- Lipid
Structures of some common lipids. At the top are cholesterol and oleic acid. The middle structure is a triglyceride composed of oleoyl, stearoyl, and palmitoyl chains attached to a glycerol backbone. At the bottom is the common phospholipid phosphatidylcholine.

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The gonane skeleton, with the IUPAC recommended numbering of the carbon atoms

Sterol

Organic compound with formula, whose molecule is derived from that of gonane by replacement of a hydrogen atom in position 3 by a hydroxyl group.

Organic compound with formula, whose molecule is derived from that of gonane by replacement of a hydrogen atom in position 3 by a hydroxyl group.

The gonane skeleton, with the IUPAC recommended numbering of the carbon atoms

While technically alcohols, sterols are classified by biochemists as lipids (fats in the broader sense of the term).

Substrate presentation; PLD (blue oval) is sequestered into cholesterol-dependent lipid domains (green lipids) by palmitoylation. PLD also binds PIP2(red hexagon) domains (grey shading) located in the disordered region of the cell with phosphatidylcholine (PC). When cholesterol decreases or PIP2 increases in the cell, PLD translocates to PIP2 where it is exposed to and hydrolizes PC to phosphatidic acid (red spherical lipid).

Cholesterol

Substrate presentation; PLD (blue oval) is sequestered into cholesterol-dependent lipid domains (green lipids) by palmitoylation. PLD also binds PIP2(red hexagon) domains (grey shading) located in the disordered region of the cell with phosphatidylcholine (PC). When cholesterol decreases or PIP2 increases in the cell, PLD translocates to PIP2 where it is exposed to and hydrolizes PC to phosphatidic acid (red spherical lipid).
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Lipid logistics: transport of triglycerides and cholesterol in organisms in form of lipoproteins as chylomicrons, VLDL, LDL, IDL, HDL.
Cholesterolemia and mortality for men and women 60 years
Reference ranges for blood tests, showing usual, as well as optimal, levels of HDL, LDL, and total cholesterol in mass and molar concentrations, is found in orange color at right, that is, among the blood constituents with the highest concentration.
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Cholesterol units conversion
Steroidogenesis, using cholesterol as building material
Space-filling model of the Cholesterol molecule
Numbering of the steroid nuclei

Cholesterol is any of a class of certain organic molecules called lipids.

Idealized representation of a molecule of a typical triglyceride, the main type of fat. Note the three fatty acid chains attached to the central glycerol portion of the molecule.

Fat

In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food.

In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food.

Idealized representation of a molecule of a typical triglyceride, the main type of fat. Note the three fatty acid chains attached to the central glycerol portion of the molecule.
Composition of fats from various foods, as percentage of their total fat
The obese mouse on the left has large stores of adipose tissue. For comparison, a mouse with a normal amount of adipose tissue is shown on the right.
Amounts of fat types in selected foods
Schematic diagram of a triglyceride with a saturated fatty acid (top), a monounsaturated one (middle) and a polyunsaturated one (bottom).
Margarine, a common product that can contain trans fatty acids
Cover of original Crisco cookbook, 1912. Crisco was made by hydrogenating cottonseed oil. The formula was revised in the 2000s and now has only a small amount of trans fat.
Wilhelm Normann patented the hydrogenation of liquid oils in 1902
Conversion of cis to trans fatty acids in partial hydrogenation
Reference ranges for blood tests, showing usual ranges for triglycerides (increasing with age) in orange at right.

The term may also be used more broadly as a synonym of lipid—any substance of biological relevance, composed of carbon, hydrogen, or oxygen, that is insoluble in water but soluble in non-polar solvents.

Simplified view of the cellular metabolism

Metabolism

Set of life-sustaining chemical reactions in organisms.

Set of life-sustaining chemical reactions in organisms.

Simplified view of the cellular metabolism
Structure of adenosine triphosphate (ATP), a central intermediate in energy metabolism
Structure of a triacylglycerol lipid
This is a diagram depicting a large set of human metabolic pathways.
Glucose can exist in both a straight-chain and ring form.
Structure of the coenzyme acetyl-CoA.The transferable acetyl group is bonded to the sulfur atom at the extreme left.
The structure of iron-containing hemoglobin. The protein subunits are in red and blue, and the iron-containing heme groups in green. From.
A simplified outline of the catabolism of proteins, carbohydrates and fats
Mechanism of ATP synthase. ATP is shown in red, ADP and phosphate in pink and the rotating stalk subunit in black.
Plant cells (bounded by purple walls) filled with chloroplasts (green), which are the site of photosynthesis
Simplified version of the steroid synthesis pathway with the intermediates isopentenyl pyrophosphate (IPP), dimethylallyl pyrophosphate (DMAPP), geranyl pyrophosphate (GPP) and squalene shown. Some intermediates are omitted for clarity.
Effect of insulin on glucose uptake and metabolism. Insulin binds to its receptor (1), which in turn starts many protein activation cascades (2). These include: translocation of Glut-4 transporter to the plasma membrane and influx of glucose (3), glycogen synthesis (4), glycolysis (5) and fatty acid synthesis (6).
Evolutionary tree showing the common ancestry of organisms from all three domains of life. Bacteria are colored blue, eukaryotes red, and archaea green. Relative positions of some of the phyla included are shown around the tree.
Metabolic network of the Arabidopsis thaliana citric acid cycle. Enzymes and metabolites are shown as red squares and the interactions between them as black lines.
Aristotle's metabolism as an open flow model
Santorio Santorio in his steelyard balance, from Ars de statica medicina, first published 1614

The three main purposes of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the conversion of food to building blocks for proteins, lipids, nucleic acids, and some carbohydrates; and the elimination of metabolic wastes.

General structures of sphingolipids

Sphingolipid

General structures of sphingolipids
Metabolic pathways of various forms of sphingolipids. Sphingolipidoses are labeled at corresponding stages that are deficient.
Sphingosine

Sphingolipids are a class of lipids containing a backbone of sphingoid bases, a set of aliphatic amino alcohols that includes sphingosine.

A bottle of glycerin purchased at a pharmacy

Glycerol

Simple polyol compound.

Simple polyol compound.

A bottle of glycerin purchased at a pharmacy
Personal lubricants commonly contain glycerol
Glycerol is an ingredient in products such as hair gel
Glycerol suppositories used as laxatives
Glycerin is often used in electronic cigarettes to create the vapor

The glycerol backbone is found in lipids known as glycerides.

A bottle of B-complex vitamin pills

Vitamin

Organic molecule that is an essential micronutrient which an organism needs in small quantities for the proper functioning of its metabolism.

Organic molecule that is an essential micronutrient which an organism needs in small quantities for the proper functioning of its metabolism.

A bottle of B-complex vitamin pills
Calcium combined with vitamin D (as calciferol) supplement tablets with fillers.
Jack Drummond's single-paragraph article in 1920 which provided structure and nomenclature used today for vitamins

Fat-soluble vitamins are absorbed through the intestinal tract with the help of lipids (fats).

An example of a phosphatidylcholine, a type of phospholipid in lecithin. Shown in – choline residue and phosphate group; – glycerol residue;  – monounsaturated fatty acid residue;  – saturated fatty acid residue.

Lecithin

An example of a phosphatidylcholine, a type of phospholipid in lecithin. Shown in – choline residue and phosphate group; – glycerol residue;  – monounsaturated fatty acid residue;  – saturated fatty acid residue.
Soy lecithin for sale at a grocery store in Uruguay

Lecithin (, from the Greek lekithos "yolk") is a generic term to designate any group of yellow-brownish fatty substances occurring in animal and plant tissues which are amphiphilic – they attract both water and fatty substances (and so are both hydrophilic and lipophilic), and are used for smoothing food textures, emulsifying, homogenizing liquid mixtures, and repelling sticking materials.

Hydrophile

Molecule or other molecular entity that is attracted to water molecules and tends to be dissolved by water.

Molecule or other molecular entity that is attracted to water molecules and tends to be dissolved by water.

An example of these amphiphilic molecules is the lipids that comprise the cell membrane.

E1 - Alprostadil

Prostaglandin

E1 - Alprostadil
I2 - Prostacyclin
Biosynthesis of eicosanoids

The prostaglandins (PG) are a group of physiologically active lipid compounds called eicosanoids having diverse hormone-like effects in animals.