Concept 5.3) Lipids include fats and steroids

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KEY TERMS

Lipid: is one of a class of water-avoiding compounds.
Hydrophobic: avoids water molecules.
Fat: is an organic compound consisting of a three-carbon back-bone (glycerol) attached to three fatty acids (: contains long hydrocarbon chains).
Saturated fat: is fat in which all three fatty acid chains contain he maximum possible number of hydrogen atoms.
Unsaturated fat: is fat with less than the maximum number of hydrogen in one or more of its fatty acid chains. This is because some of its carbon atoms are double-bonded to each other.
Steroid: is a lipid molecule with four fused carbon rings.
Cholesterol: is a steroid molecule present in the plasma membranes of animal and human cells. It can be the starting point from which your body produces other steroids.
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Lipids and Fats

• Compounds, that have characteristic of being unable to mix with the class of water, like oil, all called lipids, and they are said to be hydrophobic.
• Lipids have functions of acting as a boundary that surrounds and contains the aqueous, or watery, contents of your cells.
• Other types of lipid circulate in your body as chemical signals to cells.
• The other type of lipids is – fat, which stores energy in your body, as well as cushions your organs and provides your body with insulation.
• All the carbon atoms in the fatty acid chains form single bonds with each other, and the rest of their bonds are with hydrogen atoms.
• Saturated fat- most animal fats, such as butter.
• Unsaturated fat- generally fats in fruits, vegetables, and fish, such as corn oil, olive oil, and other vegetable oils.
• Having diets of consuming much rich saturated fats can be unhealthy, building up lipid-containing deposits within the walls of blood vessels, called plaques. Plaques can reduce blood flow, and may lead to heart diseases.
• It has hydrophillic head and hydrophobic tails.

Steroids

• Are classified as lipids because of its hydrophobic characteristics, but they are different from fats in structure and function.
• They circulate in your body as chemical signals, such as hormones.
• Cholesterol is best-known for an example of a steroid. But substances with high levels of cholesterol in the blood can link to the risk for cardiovascular (heart and blood vessel) disease.

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Concept Check
1. What is the difference between saturated and unsaturated fat?
2. What are lipids, and what are its characteristics?
3. What are steroids?