Chapter 4 Click to edit Master <a href="/keyword/subtitle-style/" >subtitle style</a> Carbon and the Molecular Diversity of Life PowerPoint Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Overview: Carbon--The Backbone of Biological Molecules Although cells are 70 95% water, the rest consists mostly of carbon-based compounds Carbon is unparalleled in its ability to form large, complex, and diverse molecules Proteins, DNA, carbohydrates, fats, and other molecules that distinguish living matter are all composed of carbon compounds Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Organic chemistry is the study of carbon compounds Organic chemistry is the study of compounds that contain carbon Organic compounds range from simple molecules to colossal ones Most organic compounds contain hydrogen atoms in addition to carbon atoms Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Vitalism, the idea that organic compounds arise only in organisms, was disproved when chemists synthesized these compounds Mechanism is the view that all natural phenomena are governed by physical and chemical laws Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings EXPERIMEN T Can <a href="/keyword/organic-molecules/" >organic molecules</a> form under conditions believed to simulate those on the early Earth? Water vapor NH 3 C H 4 &quot;Atmospher e&quot; Electro de H 2 Condens er Cooled water containing <a href="/keyword/organic-molecules/" >organic molecules</a> Col d wat er H2O &quot;se a&quot; Sample for chemical analysis Carbon atoms can form diverse molecules by bonding to four other atoms Electron configuration is the key to an atom's characteristics Electron configuration determines the kinds and number of bonds an atom will form with other atoms Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Formation of Bonds with Carbon With four valence electrons, carbon can form four covalent bonds with a variety of atoms This tetravalence makes large, complex molecules possible In molecules with multiple carbons, each carbon bonded to four other atoms has a tetrahedral shape However, when two carbon atoms are joined by a double bond, the molecule has a flat shape Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings (a) Methane Nam e Molecula r Formula Structur al Formula Ball-andStick Model Space-Filling Model (b) Ethane (c) Ethene (ethylene) Carbons linked in a linear molecule H H H H H H H H H C C C C C C C C H H H H H H H H Carbons linked in a ring H C H O CH2O H C O H O H C H C H C O H H C8H18 Octane H O C6H12O6H The electron configuration of carbon gives it covalent compatibility with many different elements The valences of carbon and its most frequent partners (hydrogen, oxygen, and nitrogen) are the &quot;building code&quot; that governs the architecture of living molecules Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 4-4 Hydrogen (valence = 1) H Oxygen (valence = 2) O Nitrogen (valence = 3) N Carbon (valence = 4) C Carbon atoms can partner with atoms other than hydrogen; for example: Carbon dioxide: CO2 O=C=O Urea: CO(NH2)2 Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 4-UN1 Ure a Molecular Diversity Arising from Carbon Skeleton Variation Carbon chains form the skeletons of most <a href="/keyword/organic-molecules/" >organic molecules</a> Carbon chains vary in length and shape Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 4-5a Ethane (a) Length Propan e Fig. 4-5b Butane (b) Branching 2-Methylpropane (commonly called isobutane) Fig. 4-5c 1-Butene (c) Double bonds 2-Butene Fig. 4-5d (d) Rings Cyclohexan e Benzene Hydrocarbons Hydrocarbons are <a href="/keyword/organic-molecules/" >organic molecules</a> consisting of only carbon and hydrogen Many <a href="/keyword/organic-molecules/" >organic molecules</a> , such as fats, have hydrocarbon components Hydrocarbons can undergo reactions that release a large amount of energy Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 4-6 Fat droplets (stained red) 100 m (a) Mammalian adipose cells (b) A fat molecule Isomers Isomers are compounds with the same molecular formula but different structures and properties: Structural isomers have different covalent arrangements of their atoms Geometric isomers have the same covalent arrangements but differ in spatial arrangements Enantiomers are isomers that are mirror images of each other Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Isomers are compounds with the same molecular formula but different structures Structural isomers have different covalent arrangements of their atoms Geometric isomers have the same covalent arrangements but differ in spatial arrangements Enantiomers are isomers that are mirror images of each other, like hands. Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Fig. 4-7 Penta ne (a) Structural isomers 2-methyl butane cis isomer: The two Xs are on the same side. (b) Geometric isomers trans isomer: The two Xs are on opposite sides. (c) Enantiomers L isomer D isomer Enantiomers are important in the pharmaceutical industry Two enantiomers of a drug may have different effects Differing effects of enantiomers demonstrate that organisms are sensitive to even subtle variations in molecules Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 4-8 Drug Conditio n Pain; inflammatio n Effective Enantiomer Ineffective Enantiomer Ibuprofe n SIbuprofen RIbuprofen Albuterol Asthma RAlbuterol SAlbuterol A small number of chemical groups are key to the functioning of biological molecules Distinctive properties of <a href="/keyword/organic-molecules/" >organic molecules</a> depend not only on the carbon skeleton but also on the molecular components attached to it A number of characteristic groups are often attached to skeletons of <a href="/keyword/organic-molecules/" >organic molecules</a> Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Chemical Groups Most Important in the Processes of Life Functional groups are the components of <a href="/keyword/organic-molecules/" >organic molecules</a> that are most commonly involved in chemical reactions The number and arrangement of functional groups give each molecule its unique properties Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Estradio l Testosteron e Picture 6 Picture 7 The Functional Groups Most Important in the Chemistry of Life Functional groups are the components of <a href="/keyword/organic-molecules/" >organic molecules</a> that are most commonly involved in chemical reactions The number and arrangement of functional groups give each molecule its unique properties Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings The seven functional groups that are most important in the chemistry of life: Hydroxyl group Carbonyl group Carboxyl group Amino group Sulfhydryl group Phosphate group Methyl group Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings LE 4-10aa Click to edit Master <a href="/keyword/subtitle-style/" >subtitle style</a> (may be written HO --) STRUCTU RE Ethanol, the alcohol present in alcoholic beverages PowerPoint Lectures for Alcohols (their specific names Biology, Seventh Edition usually end in -ol) NAME OF COMPOUNDS FUNCTIONAL PROPERTIES Is polar as a result of the electronegative oxygen atom drawing electrons toward itself. Attracts water molecules, helping dissolve organic compounds such as sugars (see Figure 5.3). Neil Campbell and Jane Reece Important in dehydration synthesis Lectures by Chris Romero Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 4-10ab Acetone, the simplest ketone Click to edit Master <a href="/keyword/subtitle-style/" >subtitle style</a> PowerPoint Lecturesgroup Ketones if the carbonyl for is Biology, Seventh Edition NAME OF COMPOUNDS Propanal, an aldehyde STRUCTU RE EXAMPLE Acetone, the simplest ketone FUNCTIONAL PROPERTIES A ketone and an aldehyde may be structural isomers with different properties, as is the case for acetone and propanal. within a carbon skeleton Aldehydes if the carbonyl group Neil Campbell and Jane Reece is at the end of the carbon skeleton Lectures by Chris Romero Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 4-10ac STRUCTURE EXAMPLE Click to edit Master <a href="/keyword/subtitle-style/" >subtitle style</a> Acetic acid, which gives vinegar its sour taste NAME OF COMPOUNDS Carboxylic acids, or organic acids FUNCTIONAL PROPERTIES Has acidic properties because it is a source of hydrogen ions. The covalent bond between oxygen and hydrogen is so polar that hydrogen ions (H+) tend to dissociate reversibly; for example, Carbonyl + hydroxyl PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Acetic Acetate acid ion In cells, found in the ionic form, which is called a carboxylate group. LE 4-10ba STRUCTURE EXAMPLE Click to edit Master <a href="/keyword/subtitle-style/" >subtitle style</a> Glycine NAME OF COMPOUNDS Amin e Because it also has a carboxyl group, glycine is both an amine and a carboxylic acid; compounds with both groups are called amino acids. FUNCTIONAL PROPERTIES Acts as a base; can pick up a proton from the surrounding solution: PowerPoint Lectures for Biology, Seventh Edition The lone electron pair can pick Neil Campbell and Janea proton up Reece Lectures by Chris Romero Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings (nonionize (ionized d) ) Ionized, with a charge of 1+, under cellular conditions LE 4-10bb Click to edit Master <a href="/keyword/subtitle-style/" >subtitle style</a> STRUCTU RE EXAMPLE (may be written HS --) sulfur has 6 valence electrons, same as oxygen &quot;molecular fastener&quot;: R-SH + HS-R become R-S-S-R (+ 2H+), stable covalent disulfide bond PowerPoint Lectures for NAME OF COMPOUNDS Biology, Seventh Edition Ethanethi ol FUNCTIONAL PROPERTIES Thio ls Neil Campbell and Jane Reece Two sulfhydryl groups can interact to help stabilize protein structure (see Figure 5.20). Lectures by Chris Romero Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 4-10bc Click to edit Master <a href="/keyword/subtitle-style/" >subtitle style</a> Glycerol phosphate STRUCTU RE EXAMPLE NAME OF COMPOUNDS PowerPoint Lectures Organic Biology, Seventh phosphates for Edition FUNCTIONAL PROPERTIES Neil Campbell and Jane Reece Makes the molecule of which it is a part an anion (negatively charged ion). Can transfer energy between <a href="/keyword/organic-molecules/" >organic molecules</a> . Lectures by Chris Romero Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings ATP: An Important Source of Energy for Cellular Processes One phosphate molecule, adenosine triphosphate (ATP), is the primary energytransferring molecule in the cell ATP consists of an organic molecule called adenosine attached to a string of three phosphate groups Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 4-UN3 Adenosin e Fig. 4-UN4 Reacts with H2O P P P ATP Adenosin e Inorganic phosphat e P i P P ADP Adenosin e Energy Fig. 4-UN5 Reacts with H2O P P P ATP Adenosin e Inorganic phosphat e P i P P ADP Adenosin e Energy You should now be able to: 1. Explain how carbon's electron configuration explains its ability to form large, complex, diverse <a href="/keyword/organic-molecules/" >organic molecules</a> Describe how carbon skeletons may vary and explain how this variation contributes to the diversity and complexity of <a href="/keyword/organic-molecules/" >organic molecules</a> Distinguish among the three types of isomers: structural, geometric, and enantiomer 2. 3. Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 4. Name the major functional groups found in <a href="/keyword/organic-molecules/" >organic molecules</a> ; describe the basic structure of each functional group and outline the chemical properties of the <a href="/keyword/organic-molecules/" >organic molecules</a> in which they occur Explain how ATP functions as the primary energy transfer molecule in living cells 5. Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The tetra-valence of carbon allows carbon to bond to H,O,N, and other carbons, forming the skeleton of diverse organic compounds Carbon skeletons vary in length and shape, and can exist as structural isomers, geometric isomers, and enantiomers Functional groups are chemically reactive groups of atoms with distinct structural and functional properties. They contribute, for example, to a molecules' solubility, polarity, stability, charge, and/or reactivity. Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Chapter 5 Click to edit Master <a href="/keyword/subtitle-style/" >subtitle style</a> The Structure and Function of Macromolecules PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Macromolecules are Polymers Polymer A high molecular weight compound consisting of long chains that may be open, closed, linear, branched, or cross linked. The chains are composed of repeating units, called monomers, which may be identical or different. Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Monomers vs. Polymers Monomer Monosaccharides (simple sugars) Acetate Amino Acids Nucleic Acids (nucleotides) Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Polymer Glycogen (animals) Cellulose (plants) Fats/Lipids Proteins DNA RNA The synthesis and breakdown of polymers Condensation or dehydration reactions require energy POLYMERIZATION Hydrolysis reactions yield energy DEPOLYMERIZATIO N Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Condensation reaction: monomer in, water out H O H O Monomer H H H O Monomer H Wate r Hydrolysis: water in, monomer out H O H H O Monomer + H O H Wate r H H O Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings H + H Monomer H Classification of Carbohydrates Carbohydrates are commonly classified on the basis of their size. Monosaccharides Oligosaccharides (few) Polysaccharides (many) Carbohydrate = carbon hydrate or hydrated carbon atoms. Saccharide is derived from the Greek sakcharon, Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Chemistry of Monosaccharides General empirical formula for carbohydrates = (CH2O)n. C is between 3 and 7 When n=3 the simplest or smallest biologically important carbohydrates are formed. polyhydroxy ketone (1) ketose polyhydroxy aldehyde (2) aldose Mono &amp; disaccharides end in the suffix &quot;ose&quot; Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 5-3 Triose sugars (C3H6O3) Pentose sugars (C5H10O5) Hexose sugars (8 types) (C6H12O6) Click to edit Master <a href="/keyword/subtitle-style/" >subtitle style</a> Aldos es Glyceraldehy de Ps Aldehyde: carbonyl carbon (C=O) is terminal Ribos e Gluco se Galacto se PowerPoint Lectures for Biology, Seventh Edition Ketos es Neil Campbell ne Jane Reece and Dihydroxyaceto Ketone: carbonyl carbon (C=O) is internal Lectures by Chris Romero Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Ribulo se Fructo se LE 5-4 Click to edit Master <a href="/keyword/subtitle-style/" >subtitle style</a> Linear PowerPoint Lectures for and ring Biology, Seventh Edition forms Abbreviated ring Structure in 3D Ring formation: O from C5 attacks carbonyl C. Neil Campbell and Jane Reece Note how carbons are numbered, starting from C=O end Lectures by Chris Romero Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Linear and ring forms of glucose Depends on whether OH is above or below the plane of the molecule: thick line is towards you, thin is away from you. Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 5-5 A disaccharide is formed when a dehydration reaction joins two monosaccharides This covalent bond is called a glycosidic linkage Click to edit Master <a href="/keyword/subtitle-style/" >subtitle style</a> Dehydration (condensation) reaction in the synthesis of maltose 1 4 glycosidic linkage Glucos e Glucos e Maltos e Dehydration reaction in the synthesis of sucrose 1 2 glycosidic linkage PowerPoint Lectures forGlucos e Biology, Seventh Edition Neil Campbell and Jane Reece Fructos e Sucros e Glycosidic linkages can be 1-2, 1-3, 1-4, 1-6 (depending on the C's involved), and or , depending on the orientation of the OH group on C1 Lectures by Chris Romero Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Polysaccharides Polysaccharides, the polymers of sugars, can be either structural molecules (cellulose) or energy storage molecules (amylose, amylopectin, glycogen) The structure and function of a polysaccharide are determined by its sugar monomers and the positions of glycosidic linkages Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Starch and cellulose structures Reactive, digestible Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Unreactive, indigestible The angle of the L 1-4 glycosidic linkage causes the polymer to assume a helical shape. Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings The flipped orientation of ,, 1-4 linkages forms straight polymers, which are stabilized by hydrogen bonds. This gives cellulose fibers the strength to support weight and stress. Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cellulose: Structural Polysaccharide Cellulose A straight chain polysaccharide composed of glucose molecules linked by means of (14) glycosidic bonds; the major structural material in the plant world. Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cellulose in plant cell walls Polysaccharides are made from sugar monomers by removal of water (=condensation synthesis) Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Energy Storage Polysaccharides Amylose The form of starch that is composed of long, (thousands) unbranched chains of glucose units which are joined by means of (14) glycosidic bonds. Amylopectin The form of starch that is composed of long, branched chains of glucose units which are joined by means of (14) and (16) glycosidic bonds. Branching =~ 1 in every 30 monomers. Glycogen A highly branched homopolysaccharide of D glucose units that is the major form of storage of carbohydrate in animals (ie in liver and muscle); the glucose units are linked by means of (14) and (16) glycosidic bonds. Branching =~ Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Enzymes that digest starch by hydrolyzing alpha linkages can't hydrolyze beta linkages in cellulose Cellulose in human food passes through the digestive tract as insoluble fiber Some microbes use enzymes to digest cellulose Many herbivores, from cows to termites, have symbiotic relationships with these microbes Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cellulose digestion: cow I am not &quot;mad&quot;, I am ruminating. Cellulase is an enzyme that digests cellulose. Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Chitin, another structural polysaccharide, is found in the exoskeleton of arthropods Chitin also provides structural support for the cell walls of many fungi Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-10 ( The a structure ) of the chitin monomer. ( Chitin forms b the ) exoskeleton of arthropods. ( c ) Chitin is used to make a strong and flexible surgical thread. Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Define &quot;polymer&quot; and discuss condensation and hydrolysis reactions with respect to polymer synthesis and breakdown. Define &quot;carbohydrate&quot; and discuss their biological functions. Differentiate an aldose from a ketose. Recognize glucose and + glucose and know how these isomers are formed. Differentiate starch from cellulose. Know what glycogen is and describe its main function. Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Lipids are a diverse group of hydrophobic molecules Lipids are the one class of large biological molecules that do not form polymers The unifying feature of lipids is having little or no affinity for water Lipids are hydrophobic because they consist mostly of hydrocarbons, which form nonpolar covalent bonds The most biologically important lipids are neutral lipids (fats and oils), phospholipids, and steroids Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Fats Fats are constructed from two types of smaller molecules: glycerol and fatty acids Glycerol is a three-carbon alcohol with a hydroxyl group attached to each carbon A fatty acid consists of a carboxyl group attached to a long carbon skeleton (even numbered, usually between 14 and 22) Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings A fatty acid consists of a carboxyl group attached to a long carbon skeleton (even numbered, usually between 14 and 22 Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Glycerol is a threecarbon alcohol with a hydroxyl group attached to each carbon Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Structure of a fat If the fatty acid chain has no double bonds (C=C) =&gt; saturated. (removal of water) If the fatty acid chain has double bonds (C=C) =&gt; unsaturated. (=triglyceride) Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Fatty acids vary in length (number of carbons) and in the number and locations of double bonds Saturated fatty acids have the maximum number of hydrogen atoms possible and no double bonds Unsaturated fatty acids have one or more double bonds. They can be commercially hydrogenated to make margarine or shortening. In a fat molecule, the 3 fatty acids may be the same or different, and different organisms use different combinations. Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Fats made from saturated fatty acids are called saturated fats Most animal fats are saturated Saturated fats are solid at room temperature A diet rich in saturated fats may contribute to cardiovascular disease through plaque deposits Click to edit Master <a href="/keyword/subtitle-style/" >subtitle style</a> Stearic acid PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Saturated fat and fatty acid. Lectures by Chris Romero Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Fats made from unsaturated fatty acids are called unsaturated fats Plant fats and fish fats are usually unsaturated Plant fats and fish fats are liquid at room temperature and are called oils Click to edit Master <a href="/keyword/subtitle-style/" >subtitle style</a> Oleic acid PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero and fatty acid. Unsaturated fat Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings cis double bond causes bending, which makes it more Waxes Waxes are harder and less greasy than fats. They contain fatty acids combined with other alcohols and hydrocarbons. Plants secrete waxes for protection and to prevent water loss. Beeswax forms honeycombs Aquatic life use waxes as waterproofing. Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Phospholipids In a phospholipid, two fatty acids and a phosphate group are attached to glycerol The two fatty acid tails are hydrophobic, but the phosphate group and its attachments form a hydrophilic head Amphipathic (hydrophobic + hydrophilic) Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Structure of a phospholipid Double bond in unsaturated fatty acid chain often bends. The resulting &quot;kink&quot; prevents close packing of phospholipids within membrane Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Phospholipid membranes When phospholipids are placed in aqueous environment, they arrange themselves to form: Phospholipid bilayer H2 O Major component of biological membranes or phospholipid micelle H2 O Such that hydrophobic tails face each other and hydrophilic heads face toward water Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings H2 O H2 O LE 5-14 Click to edit Master <a href="/keyword/subtitle-style/" >subtitle style</a> PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Hydrophili c head WATE R Hydrophobic tails WATE R Lectures by Chris Romero Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Steroids Steroids are lipids characterized by a carbon skeleton consisting of four fused rings Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Sterols Sterols are steroids with a polar OH group on one end, and a non-polar hydrocarbon on the other end. They are amphipathic. Functional groups 4 fused rings (6,6,6,5) Cholestero l Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Estradi ol Click to edit Master <a href="/keyword/subtitle-style/" >subtitle style</a> other hormones are peptides Female lion Steroid hormones control development, behavior, and biochemical processes. Steroid hormones are derived from cholesterol. PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Testostero ne Lectures by Chris Romero Male lion Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings