5.3

• A general characteristic of lipids is their inability to mix with water, a property known as hydrophobic.
• Fats and steroids are two types of lipids.
• Fats consist of a three-carbon backbone called glycerol attached to three fatty acids, which contain long hydrocarbon chains.
• Some fats are solid at room temperature, while others, called oils, are liquids at room temperature.
• Fatty tissues cushion organs and provide insulation.
• Certain vegetable oils contain unsaturated fat molecules, which have at least one double bond in at least one of the fatty acid chains.
• A saturated fat is a fat in which all three fatty acid chains contain the maximum possible number of hydrogen atoms.
• Unsaturated fats contain less than the maximum number of hydrogen atoms in one or more of their fatty acid chains because some of their carbon atoms are double-bonded to each other.
• Diets rich in saturated fats may be unhealthy as they may promote the buildup of lipid-containing deposits, called plaques, within the walls of blood vessels.
• A lipid molecule in which the carbon skeleton forms four fused rings is called a steroid.
• Steroids are classified as lipids because they are hydrophobic, but they are very different from fats in structure and function.
• Some steroids circulate in the body as chemical signals.
• The steroids estrogen, a female sex hormone, and testosterone, a male sex hormone, function in this way.
• Cholesterol is an essential molecule found in the membranes that surround cells and is also the starting point from which the body produces other steroids.
• Despite its necessity, cholesterol has a bad reputation because high levels of particular cholesterol-containing substances in the blood are linked to increased risk for cardiovascular disease.
• Describe the structure and function of fats
• Explain how fatty acids can be used by the body as fuel or stored as energy reserves
• Define triglycerides and describe their role in storing excess calories
• Discuss the importance of dietary fats and explain why some types of fats may have negative health effects
• Identify common sources of saturated and unsaturated fats in the diet
• Describe the structure and function of fats and oils: Fats are solid at room temperature and are made up of long chains of hydrocarbon molecules
• Fats contain glycerol, which is an alcohol with three carbon atoms.
• Fatty acid molecules attach to the glycerol through ester bonds.
• The fatty acid tails vary in length and number of double bonds between carbons.
• Fatty acids are organic compounds that consist of a chain of carbon atoms bonded to hydrogen atoms.
• Oils are liquid at room temperature because they do not contain any ester bonds between the glycerol and fatty acid molecules.
• Describe the structure and function of steroids: Steroids are lipids with four carbon rings and are used for hormones
• Cholesterol is a type of steroid found in animal cells and is important for cell membrane stability and as a precursor for other substances such as vitamin D and sex hormones.
• Unsaturated fats can be monounsaturated (one double bond) or polyunsaturated (more than one double bond).
• What is a steroid hormone? A hormone that is produced by the adrenal glands and is responsible for regulating the body's response to stress
• • How are steroids different from fats?

  Steroids are a type of lipid, while fats are a specific type of steroid.