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Unit 8- Biochemistry

This assignment provides an overview of lipids, key biomolecules composed of carbon, hydrogen, oxygen, and sometimes phosphorus. It outlines the two main types of lipids: those with fatty acids (e.g., triglycerides, phospholipids, and waxes) and those without (e.g., steroids). The functions of fats in the body and food are discussed, highlighting their roles in energy storage, membrane structure, and nutrient absorption. Lipid terminology, including fatty acid characteristics, is detailed, focusing on their saturation levels and sources, including cholesterol's role in health.

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Unit 8- Biochemistry

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  1. Unit 8- Biochemistry Notes- Lipids Assignment #6

  2. What Elements are in a Lipid? • Carbon • Hydrogen • Oxygen • Phosphorus

  3. Types of Lipids • Lipids with fatty acids Waxes Fats and oils (trigycerides) Phospholipids • Lipids without fatty acids Steroids

  4. Phospholipids: Plasma Membrane Steroids: Cholesterol and sex hormones Waxes: Ear Wax Fats: Under Skin Where Are Lipids Found?

  5. A Primer on Fats • The Functions of Fat in the Body • Energy source esp. for muscles • Serves as an energy reserve • 30-50% of stored fat

  6. A Primer on Fats • Major component of cell membranes • Nourishes skin & hair • Insulates the body from temperature extremes • Cushion the vital organs to protect them from shock

  7. Lipids in Foods

  8. The Functions of Fat in Food • Provide calories (9 per gram) • Provide satiety (makes you feel full) • Carry fat-soluble vitamins & essential fatty acids • Contribute aroma & flavor

  9. Fatty Acids • Long-chain carboxylic acids • Insoluble in water (they do not dissolve) • Typically 12-18 carbon atoms (even number) • Some contain double bonds corn oil contains 86% unsaturated fatty acids and 14% saturated fatty acids

  10. Lipid Terminology • Triglycerides: the major class of dietary lipids, including fats & oils • Made up of 3 units known as fatty acids and 1 unit called glycerol (backbone) • Comprise about 95% of lipids in food and the human body

  11. Lipid Terminology • Phospholipids: • 2nd of three main classes of lipids • similar to a triglyceride, but contains phosphorous • Sterols • 3rd of three main classes of lipids; • Cholesterol • one of the sterols • manufactured in the body for a variety of purposes

  12. Lipid Terminology • Fatty acids: • basic units of fat composed of chains of carbon atoms • an acid group at one end and hydrogen atoms attached all along their length

  13. A Closer View of Fats • Chain Length (number of carbons linked together) • Shorter = more soluble in water • Saturated vs. Unsaturated (number of hydrogens the chain is holding) • Maximum = saturated • Unsaturated = one or more is missing • Point of unsaturation = site where hydrogen is missing

  14. A Closer View of Fats • Saturated fatty acid: a fatty acid carrying the maximum possible number of hydrogen atoms • Animal foods such as meat, poultry and full-fat dairy products • Tropical oils such as palm and coconut

  15. A Closer View of Fats • Unsaturated fatty acid: a fatty acid with one or more points of unsaturation. • Found in foods from both plants & animal sources • Monounsaturated fatty acids (one double bond) • Polyunsaturated fatty acids (two or more)

  16. Properties of SaturatedFatty Acids • Contain only single C–C bonds • Closely packed • Strong attractions between chains • High melting points • Solids at room temperature

  17. Properties of UnsaturatedFatty Acids • Contain one or more double C=C bonds • Nonlinear chains do not allow molecules to pack closely • Few interactions between chains • Low melting points • Liquids at room temperature

  18. Cholesterol – a Sterol • Found only in animal products • Also made & used in the body: • Structure of cell membranes • Used to make bile for digestion • Bile: a mixture of compounds, made by the liver, stored in the gallbladder, & secreted into the small intestine • Emulsifies lipids to prepare them for digestion & helps transport them into the intestinal wall cells

  19. Cholesterol – a Sterol • Used to make the sex hormones estrogen & testosterone • Made into vitamin D with the help of sunlight • Deposited in the artery walls leading to plaque buildup & heart disease

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