Quiz 5: Lipids
Margarine is primarily used as a substitute for butter and produced from vegetable oils or fats. Conversion to margarine increases its shelf life and reduces the incidence of rancidity caused by oxidation. Margarine is produced from vegetable oils which have unsaturated carbon atoms, that is carbon atoms bonded to each other by double bonds. Margarine is saturated compound having carbon-carbon single bonds. Though the process results in a saturated product, it is not referred to as saturation, but by another name that points to the changes that are responsible for bringing about the saturation. Esterification is the process of conversion of a carboxylic acid and alcohol to an ester. Margarine is produced from vegetable oils or fats and not carboxylic acids, and margarine is not an ester but a type of fat. Isomerization is the process by which a compound having the same atomic composition is produced with a different orientation or structure. Margarine is produced from vegetable oils or fats that have less hydrogen atoms compared to margarine, which means its atomic composition changes after the process. Thus, the options a, b, and c would be incorrect. Unsaturated organic compounds having double bonds are converted to saturated compounds by various means. One of the ways is to add hydrogen atom to one of the carbons forming the double bond. The process is referred to as hydrogenation. Vegetable oils or fats are converted to margarine by passing hydrogen under pressure. Margarine is made by the process of hydrogenation. Thus, the correct option would be the option .
Fatty acids are organic molecules comprising of carbon and hydrogen atoms. They have the carboxylic group (-COOH) in their structure which classifies them chemically as carboxylic acids. Fatty acids can broadly be classified, based on their structure, as saturated and unsaturated fatty acids. The unsaturated fatty acids can be further classified into monounsaturated and polyunsaturated fatty acids. Saturated fatty acids comprise of carbon atoms bound by carbon-carbon single bonds. They have a straight and linear structure, and thus are densely packed. At room temperature therefore there can exist as solids. Triglycerides are an example of saturated fatty acids commonly found in food as well as the body. The polyunsaturated fatty acids (PUFA) have carbon atoms bound by carbon-carbon double bonds. When the carbon atoms are oriented in opposite directions, the polyunsaturated fatty acids are referred to as trans fatty acids. They exist mostly as liquids at room temperature such as corn, sunflower, safflower, and soybean oils. Omega-3 (linolenic acid), omega-6 (linoleic acid), and omega-9 are some of the important polyunsaturated fatty acids. They have the carbon-carbon double bonds are the third, sixth, and ninth carbon atoms, respectively. While the latter is made in the body, the former two are not and hence referred to as essential fatty acids. Nuts, seeds, fatty fish, and canola oil are important sources of omega-3 fatty acids. beef, poultry safflower oil, and corn oil are rich sources of omega-6 fatty acids. Fatty acids play the important role of providing energy to the body when glucose is not available. They form the building blocks of hormone-like substances such as prostaglandins and other hormones. When energy from fatty acids is not required, the surplus fatty acids are stored in the form of triglycerides. Triglycerides form the visceral and body fat and help in transportation of the fat-soluble vitamins. While saturated fatty acids play an important role in the normal physiology of the body, their consumption at higher levels increases the low-density cholesterol in the blood, leading to fat deposition in the vessels, narrowing the channel and reducing the capacity of the blood to deliver oxygen. Saturated fatty acids must be consumed in restricted amounts. Like the saturated fatty acids, the trans fatty acids too can have a harmful effect on the body due to their tendency to increase the low-density cholesterol levels. Among the unsaturated fatty acids, the essential fatty acids, namely, omega-3 and omega-6 are beneficial to the body. Omega-3 has anticoagulative properties and tend to increase the levels of prostacyclin which discourages clotting of blood. They tend to reduce the blood pressure and inflammatory responses in the body. The omega-6 fatty acids tend to increase the clotting of blood.
When the body is deficient in carbohydrates, fatty acids provide energy by the process of gluconeogenesis. The body, however, cannot produce all the fatty acids required by it. Some of the fatty acids need to be consumed from dietary sources. These fatty acids are referred to as essential fatty acids. The ones that can be produced in the body are referred to as non-essential fatty acids. Omega 6 is an essential fatty acid that helps in the production of factors that cause clotting. Omega-9 is a fatty acid that can be produced by the body and is not an essential fatty acid. It helps in increasing the high-density cholesterol and reducing the low-density cholesterol but has not role in the clotting mechanism. Prostacyclin helps in preventing aggregation of platelets and is produced by endothelial and vascular muscle cells. It prevents clotting of blood, but it is a hormone-like substance and not a fatty acid.Thus, options b, c, and d are incorrect. Studies conducted in surgical experiments have shown the influence of omega-3 in releasing prostacyclin from the vascular tissues, resulting in less bleeding during surgery. Omega 3 is an essential fatty acid that facilitates the secretion of hormone-like substances such as prostacyclin that tend to reduce blood-clotting by inhibiting platelet activation. Thus, the correct option would be the option .