Lipids
Lipids are unique in the sense that they do not have polymers and monomers. The unifying trait of all lipids is they are all hydrophobic, in other words, they have very little affinity for water.
Triglycerides
Also called a triacylglycerol, this kind of fat is made from the synthesis of three fatty acids and one glycerol molecule. Fatty acids are long chains of carbon and hydrogen. They contain a lot of energy, which makes fats ideal for energy storage. The glycerol simply holds the fatty acids together.
If a fatty acid chain has no double bonds between its carbons, then it has the greatest possible ratio of hydrogen to carbon atoms. Therefore we call this fatty acid saturated. If all three of the fatty acids in a triglycerol are saturated, this entire molecule of fat is a saturated fat. On the other hand, if a fatty acid has one or more double bonds between carbon atoms, then it's unsaturated. Even if one of the fatty acids in a triglycerol isn't saturated, we call it an unsaturated fat.
Saturated fats are solid at room temperature, and they usually come from animals. A diet rich in saturated fats can lead to cardiovascular disease. An example would be lard. Unsaturated fats are liquid at room temperature, and we obtain them from fish or plants. Unsaturated fats are usually healthier than their saturated counterparts. Vegetable oil is an unsaturated fat.
If a fatty acid chain has no double bonds between its carbons, then it has the greatest possible ratio of hydrogen to carbon atoms. Therefore we call this fatty acid saturated. If all three of the fatty acids in a triglycerol are saturated, this entire molecule of fat is a saturated fat. On the other hand, if a fatty acid has one or more double bonds between carbon atoms, then it's unsaturated. Even if one of the fatty acids in a triglycerol isn't saturated, we call it an unsaturated fat.
Saturated fats are solid at room temperature, and they usually come from animals. A diet rich in saturated fats can lead to cardiovascular disease. An example would be lard. Unsaturated fats are liquid at room temperature, and we obtain them from fish or plants. Unsaturated fats are usually healthier than their saturated counterparts. Vegetable oil is an unsaturated fat.
PhospholipidsPhospholipids are an important component of our cell membranes. They are made of one glycerol, two fatty acids, and one phosphate group. In fact, a phospholipid is essentially a triglycerol with one of its fatty acid chains replaced with a phosphate group. The two fatty acids make up the "tail" of the molecule, and the phosphate group is the "head". Because the tails are non-polar, they are hydrophobic. On the contrary, the polar nature of the phosphate group makes the head region hydrophilic. However, just because the phosphate is hydrophilic doesn't mean the molecule can dissolve in water. When phospholipids are placed in water, they will form a bilayer, such that the hydrophilic heads are exposed to the water and the hydrophobic tail regions are sandwiched between the hydrophilic heads (see liposome in the image).
Phospholipids arranged in the bilayer sheet form makes up the backbone of our cell membranes, as well as the membranes of many organelles. |
Steroids
Steroids include lipids with a four-ring carbon skeleton. An important steroid is cholesterol. It is a component of cell membranes and many of our hormones are derived from cholesterol. However, a high level of it may lead to atherosclerosis. Eating too much saturated fats can increase cholesterol levels.
Trans Fats/Hydrogenated Oils
Sometimes food processors artificially make saturated fats from unsaturated fats by adding hydrogen to them (hydrogenating). Common examples are margarine and peanut butter. Not only does this process create unhealthy saturated fats, it may also produce trans fats in the process.
Usually unsaturated fats have a cis-double bond. However, trans fats have a trans-double bond. Although they are isomers to each other, their effects on the body are different. Trans fats tend to be more unhealthy than natural unsaturated fats. |
It is important to note that despite some unhealthy connotations associated with fats, they are still an essential part of our diet. Unsaturated fats are usually the best option, and we should try to limit our consumption of saturated and trans fats.