15.1 Intro to Lipids Lipids are biochemical molecules that are insoluble or sparingly soluble in water, but are soluble in nonpolar organic solvents.

Name: 15.1 Intro to Lipids Lipids are biochemical molecules that are insoluble or sparingly soluble in water, but are soluble in nonpolar organic solvents.
Uploaded: 2017-12-05T22:27:49+00:00
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Description: 15.1 Intro to Lipids Lipids are biochemical molecules that are insoluble or sparingly soluble in water, but are soluble in nonpolar organic solvents.

15.1 Intro to Lipids Lipids are biochemical molecules that are insoluble or sparingly soluble in water, but are soluble in nonpolar organic solvents. Uses of lipids: Storage of energy Insulation Protection from mechanical damage Major component of cell membranes Copyright © Houghton Mifflin Company. All rights reserved.

15.1 Intro to Lipids Types of lipids:
Saponifiable lipids contain fatty acids bound as esters. Saponification (soap-making) is hydrolysis of the esters and frees the fatty acids. These lipids can be classified as polar or nonpolar. II. Nonsaponifiable lipids do not contain fatty acids bound as esters. Copyright © Houghton Mifflin Company. All rights reserved.

15.2 Structures of Fatty Acids
Fatty acids are carboxylic acids with un-branched hydrocarbon chains. They contain an even number of carbon atoms. Fatty acids can be saturated: contain no double bonds monunsaturated: contain one double bond polyunsaturated: contain several double bonds Copyright © Houghton Mifflin Company. All rights reserved.

The double bonds in naturally-occurring fatty acids have cis double bonds. These put kinks in the hydrocarbon backbone. Two of the polyunsaturated fatty acids are essential in the diet; they cannot be syn-thesized by the body. Both contain 18 carbon atoms. Fish and vegetable oils are dietary sources of these fatty acids. Linoleic acid (2 double bonds) Linolenic acid (3 double bonds) Copyright © Houghton Mifflin Company. All rights reserved.

15.3 Properties of Fatty Acids
The melting points of fatty acids depend on the num-ber of carbon atoms and the degree of unsaturation. Copyright © Houghton Mifflin Company. All rights reserved.

The bent shapes of unsaturated fatty acids pre-vent them from fitting together and forming high-melting solids. Fatty acids with trans double bonds are found in “trans fats.” The trans double bonds are formed when vegetable oils are processed. These fatty acids have higher melting points than the cis isomers. Copyright © Houghton Mifflin Company. All rights reserved.

15.4 Triglycerides Triglycerides are triesters. They are products of the reaction of glycerol and fatty acids. They are also called triacylglycerols, and are the nonpolar saponifiable lipids. Copyright © Houghton Mifflin Company. All rights reserved.

15.4 Triglycerides Triglycerides are the most abundant lipids, and are used for storage of energy. Solid or semisolid triglycerides are called fats. They contain mainly saturated fatty acids. They are found in meats and tropical nuts. Liquid triglycerides are called fats. They contain mainly unsaturated fatty acids. They are found in fish and plants. Copyright © Houghton Mifflin Company. All rights reserved.

15.4 Triglycerides Fatty acid contents of common fats and oils.
Copyright © Houghton Mifflin Company. All rights reserved.

15.5 Reactions of Triglycerides
Complete hydrolysis of triglycerides produces the triol, glycerol, and free fatty acids. Metabolic hydrolysis requires enzymes from the pancreas. Usually, two of the fatty acids are hydrolyzed, leaving a monoglyceride. Copyright © Houghton Mifflin Company. All rights reserved.

Saponification is hydrolysis of triglycerides in basic solution. The fatty acid is obtained as its carboxylate salt, or soap. The carboxylate anion has a polar end and a nonpolar hydrocarbon chain. The polar end is hydrophilic (water-loving) and the nonpo-lar chain is hydrophobic (water-fearing.) Copyright © Houghton Mifflin Company. All rights reserved.

15.6 Phosphoglycerides Phosphoglycerides are polar saponifiable lipids. Two of the alcohols on glycerol are esterified with fatty acids. The third is esterified with phosphoric acid, which is esterified with an aminoalcohol. Copyright © Houghton Mifflin Company. All rights reserved.

15.6 Phosphoglycerides Phosphatidylcholines form micelles and are good emulsifiers. They are major components of cell membranes. They are abundant in egg yolk and soybeans. Copyright © Houghton Mifflin Company. All rights reserved.

15.7 Sphingolipids Sphingolipids are polar saponifiable lipids based on sphingosine rather than glycerol. A fatty acid is bonded to the nitrogen as an amide. Copyright © Houghton Mifflin Company. All rights reserved.

15.8 Steroids Cholesterol, when mixed with a fat or oil, enables the substance to absorb a fair amount of water. Cholesterol is abundant in wool fat, a.k.a. lanolin. Cholesterol is used as a grease vehicle in ointments when water-soluble com-ponents are required. Copyright © Houghton Mifflin Company. All rights reserved.

15.8 Steroids Cholesterol is a precursor to other important steroids
Bile salts Hormones Vitamin D Cholesterol is a risk factor for atherosclerosis, a buildup of plaque, in the arteries. Copyright © Houghton Mifflin Company. All rights reserved.

15.8 Steroids Hormones are messenger molecules produced in ductless glands. They are carried to specific tissues where they trigger a response. Steroid hormones regulate “sugar, salt, and sex!” Adrenocortical steroids regulate sugar and salt. They are secreted by the adrenal glands. Some are used as anti-inflammatory drugs. Copyright © Houghton Mifflin Company. All rights reserved.

15.8 Steroids Estrogens are steroid hormones that cause development of secondary sex characteristics in females and regulate the menstrual cycle. Progestins are steroid hormones that regulate pregnancy. Androgens promote development of secondary sex characteristics in males and promote muscle growth. They are sometimes called anabolic steroids. Copyright © Houghton Mifflin Company. All rights reserved.

15.8 Steroids Estrogens are steroid hormones that cause development of secondary sex characteristics in females and regulate the menstrual cycle. Progestins are steroid hormones that regulate pregnancy. Androgens promote development of secondary sex characteristics in males and promote muscle growth. Copyright © Houghton Mifflin Company. All rights reserved.

15.8 Steroids Many synthetic steroids are available as drugs. Anabolic steroids cause the body to increase protein synthesis, especially in the muscles. They also prevent the breakdown of muscle tissue and affect cell differentiation, favoring muscle over fat cells. Side effects include acne, liver disease, infer-tility, and development of inappropriate sec-ondary sex characteristics. They can stunt growth in puberty and affect sex character-istics of unborn infants. Copyright © Houghton Mifflin Company. All rights reserved.

15.8 Steroids Tamoxifen and raloxifene are selective estrogen receptor modulators, a.k.a. SERMs, that block estrogen receptors and slow or prevent growth of breast cancer. Copyright © Houghton Mifflin Company. All rights reserved.

15.8 Steroids Diethylstilbestrol, a.k.a. DES, was used in 1940’s and 1950’s to prevent miscarriage. It caused vaginal cancer in daughters of women who took it. (Rare) It caused premature labor in daughters of women who took it. (Common) Copyright © Houghton Mifflin Company. All rights reserved.

Prostaglandins Prostaglandins are lipids derived from arachidonic acid. They were first isolated from prostate glands. Prostaglandins have hormone-like prop-erties and are involved in inflammation. Aspirin blocks production of prostaglandins. Copyright © Houghton Mifflin Company. All rights reserved.

Prostaglandins Prostaglandins are lipids derived from arachidonic acid. They have hormone-like properties. They are involved in inflammation; aspirin blocks production of prostaglandins. Copyright © Houghton Mifflin Company. All rights reserved.

15.9 Cell Membranes Cell membranes separate the aqueous environment inside the cell from the external aqueous environment. The membrane also controls movement of substances into and out of the cell. Phospholipids are a major component of cell membranes. They form lipid bilayers. Copyright © Houghton Mifflin Company. All rights reserved.

15.9 Cell Membranes The membrane also controls movement of substances into and out of the cell. Phospholipids are a major component of cell membranes. They form lipid bilayers. Copyright © Houghton Mifflin Company. All rights reserved.

15.9 Cell Membranes The kinks associated with cis double bonds in fatty acid chains prevent tight packing of the lipid molecules in a lipid bilayer. Copyright © Houghton Mifflin Company. All rights reserved.

15.9 Cell Membranes Proteins are also components of the membrane. They help move nutrients, and act as receptors for hormones and neurotransmitters. Copyright © Houghton Mifflin Company. All rights reserved.

15.1 Intro to Lipids Lipids are biochemical molecules that are insoluble or sparingly soluble in water, but are soluble in nonpolar organic solvents.

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15.1 Intro to Lipids Lipids are biochemical molecules that are insoluble or sparingly soluble in water, but are soluble in nonpolar organic solvents.

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Presentation on theme: "15.1 Intro to Lipids Lipids are biochemical molecules that are insoluble or sparingly soluble in water, but are soluble in nonpolar organic solvents."— Presentation transcript:

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