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Unit 8- Biochemistry

Unit 8- Biochemistry. Notes- Lipids Assignment #6. What Elements are in a Lipid ?. Carbon Hydrogen Oxygen Phosphorus. Types of Lipids. Lipids with fatty acids Waxes Fats and oils ( trigycerides ) Phospholipids Lipids without fatty acids Steroids. Phospholipids:

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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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