Carbohydrates Chapter 13 PDF

13 1. Carbohydrates carbohydrates - made of carbon , hydrogen , and oxygen There are many c...

13 1. Carbohydrates carbohydrates - made of carbon , hydrogen , and oxygen There are many carbohydrates in food : Cn(H20)n ↳ polysaccharides called starches in bread and pasta - ↳ tablesugar is sucrose , a disaccharide that consists of two simple sugars , glucose and fructose 3 lactose in milk (glucose and galactose) ↳ cellulose photosynthesis energy from the sun is used to combine the carbon atoms - from carbon dioxide and the hydrogen and oxygen atoms of water into the carbohydrate Glucose (and 02). Photosynthesis 6CO2 + 6H2O + GO energyaspiration CotizO In the body glucose is oxidized in a series of metabolic reactions known as , respiration which releases chemical energy to do work in the Cells CO2 and H20 ,. are produced and returned to the atmosphere. carbon cycle - The combination of photosynthesis and respiration in , which energy from the Sun is stored in plants by photosynthesis and made available to us when the carbohydrates in our diets are metabolized. Types of Carbohydrates monosaccharides /Simplest) cannot be split or hydrolyzed into smaller carbohydrates ↳ example : glucose CH 20 , i disaccharide - consists of two monosaccharide units joined together which , can be split example : table Sugar (sucrose) Ci2HzcO , Can be split water (hudvolusis) in the presence of an 6 , by acid or an enzyme to give one molecule of glucose and one molecule of frUCtuSe (amonosaccharide CrHaatHa0 , CuttizOutCuHiaDo sucrose Het or oucose Fructose enzyme  polysaccharide - a carbohydrate that contains many monosaccharide units which , is called polymer In the presence of an acid or an enzyme a polysaccharide a. , can be completely hydrolyzed to yield many monosaccharide molecules Monosaccharides contains several hydroxyl groups attached to a chain of three to seven carbon - atoms that also contains an aldehyde or a before group - monosaccharide also known as a polyhydroxy aldehyde or polyhydroxy ketone aldose- first carbon in the chain is an aldenude refose-has a before as the second carbon atom Monosaccharicles are classified by the number of carbon atoms triose a monosaccharide with three Carbon atoms - tetrose - one with four carbon atoms penfuse - has five carbon atoms nexose contains six carbons Ribose - five-carbon monosaccharide that is an aldenude aldopentose - six-carbon monosaccharide that is a ketone Ketonexose -  13 2 Chiral Molecules. When mirror images cannot be completely matched they are nonsuperimposable , chiral-objects such as hands that have non-superimposable mirror images achival when the mirror image of an object is identical and can be superimposed - on the original Chival Carbon Atoms A carbon atom is chival if it has at least one carbon atom bonded to four different atoms or groups. - there are two different ways that it can be bonded to four atoms or groups of atoms < the resulting structures are nonsuperimposable mirror images , or stereoisomers. stereoisomers - when two or more chiral structures have the same molecular formula , but differ in the three-dimensional arrangements of atoms in space when sterioisomers cannot be superimposed they are , called enantiomers Achival Objects When the mirror image of an achival structure is rotated and the structures , can be aligned their mirror images , are superimposable Fischer projection - system for drawing isomers that shows the arrangements of the atoms around the chiral carbons fischer projection : a model used to represent a three-dimensional structure of enationers. &  ↳ vertical lines = bonds that project backward from a carbon atom ↳ horizontal lines bonds that project forward : 3 the most highly oxidized carbon is placed at the top ↳ the intersections of vertical and horizontal lines represent a Carbon atom (ii) for glyceral denyde (farthest from the top) - ↳ the isomer that has the-of group drawn to the left of the chiral Atom Lisomer : ↳ the isomer that has the-of group drawn to the right of the Chiral Atom Disomer : fischer projections for compounds that have 2+ chiral carbons 4 Then the designation as a D or Lisomer is determined by the position of the Oh group attached to the chiral carbon farthest from the carbonyl group - 13 3 FischerProjections of Monosaccharides. The most common monosaccharides contain five or six carbon atoms with several - chiral carbons. - Each fischer projection of a monosaccharide can be drawn as a mirror image which , gives a pair of enantioners Some Important Monosaccharides 3 D-Glucose D-galactose all nexoses with the molecular formula CoHizO D-fructose ↳ the D nature and used in the enantiomers are more commonly foundin cells of the body most D-glucose CoHizO (dextrose/blood sugar) found in fruits vegetables corn syrup a honey - , , , - , common a building block of the disaccharides sucrose lactuse and maltose and - , , , polysaccharides such as amylose Cellulose and glycogen 3 , , only difference is the arrangement of the -oh group on carbon a D-Galactose CHi20 , - is obtained from the disaccharide lactose which is found in , milk/milk products is important in the cellular membranes of the brain and nervous system - D-fructose , CoHi20 is a ketonexose the structure of D-fructose differs from glucose atCarbons 1 and 2 by the - location of the carbonyl group the sweetest of the carbohydrates - also called levulose and fruit sugar found in honey a fruit ;vices - , ↳ it is obtained as one of the hydrolysis products of sucrose the disaccharide , known as table sugar 3 HFCS is the sweetener produced when enzymes convert the glucose in corn syrup to fructose. When fructose is mixed with corn surup containing only glucose , the sweether HFCS is produced. 13 4 Haworth. Structures of Monosaccharides The most stable form of pentoses and nexoses are five/six atom rings rather than open chains. These rings are known as Haworth structures Haworth structures are produced from the reaction of a carbonyl group and a hydroxyl group in the same molecule  Drawing Haworth structures for D-glucose from its fischer projection To convert a Fischer projection to a Haworth structure turn the fischer - , projection clockwise by 900 The-Hand-on groups on the right of the vertical carbon are now below the horizontal carbon chain. Those on the left of the open chain are now above the horizontal carbon chain. with Carbons 2 and 3 as the base of nexagon more the remaining - a , carbons upward. Rotate the groups on carbon s so that the-on group is close to carbon 1 -. To complete the Haworth structure , draw a bond from the oxygen of the - - oH group on carbon 5 to Carbon 1. For. line-angle-carbons are corners. Mutarotation of a- and B-D-Glucose In an aqueous solution theHaworth structure of a-D-glucose opens to - , give the open chain of D-glucose which has an aldehyde group. , However , when the open chain closes again it can form B-D-glucose - ↳ In this process called mutarotation each isomer converts to the open chain and back , again. As the ring opens and closes , the-oH group on carbon 1 can form either the a or Bisomer. Haworth Structures of Galactose Galactose is an aldonexose that differs from glucose only in the arrangement of the-of group on Carbon 4. Thus , its Haworth structure is similar to glucose , except that the-on on carbon 4 is drawn above the vina. group le Galactose also exists as a and B isomers T Haworth Structures of fructose L fructose is a ketonexose so the Haworth structure for fructose is , a five-atom ring with Carbon 2 at the right corner of the ring.The cyclic structure forms when the -on group on carbon 5 bonds to Carbon 2 in the carbonyl group. The new-oH group on carbon gives a and Bisomers to fructose. 13 5. Chemical properties ofMonosaccharides Monosaccharides contain functional groups that can undergo chemical reactions 1) In an aldose the aldehyde , group can be oxidized to a carboxylic acid. 2) In both an aldose d a before the , carbonyl group can be reduced to give a hydroxyl group 3) The hydroxyl groups can react with other compounds to form a variety of derivates that are important in biological structures. Oxidation of Monosaccharides Although monosaccharides exist mostly in cyclic forms , a small amount of the open- chain form is always present which provides , an aldehyde group. An aldenyde group with adjacent hydroxyl can be oxidized to a carboxylic acid by an - an - oxidizing agent such as benedicts reagent. The Sugar acids are named by replacing the ose ending of the monosaccharide with - onic acid.Then the Cut is reduced to Cut which forms a brick-red precipitate of , CuzO. reducing sugar : A carbohydrate that reduces another substance  fructose , a ketohexose is also a , reducing sugar 6 betone cannot be oxidized usually a - However in, a basic Benedict's solution , a rearrangement occurs between the before group on carbon 2 and the hydroxyl group on Carbon 1. - As a result fructose is converted to , glucose , which produces an aldehyde group with an adjacent hydroxyl that can be oxidized Reduction of Monosaccharides - The reduction of the carbonyl group in monosaccharides produces sugar alcohols which are also called alditols D Glucose is reduced to D-gluciful better known ,. - , as D-Sorbitol. The sugar alcohols are named by replacing the ose ending of the monosaccharide - with itol (ex D-Sorbitol , D- Xylitol.. from D-Xylose. and D-mannitol from D-mannose) ↳ The of cataracts in diabetics is attributed to the accumulation of development D-sorbitol in the lens of the eye  13 6 Disaccharides. A disaccharide is composed of two monosaccharides linked together. ↳ most common : maltose lactose a sucrose , , - when two monosaccharides combine in a dehydration reaction the product is , a disaccharide ↳ and water. 6 The reaction occurs between the hydroxyl group on carbon 1 and one of the hydroxyl groups on the second monosaccharide MaltoseSynthase Glucose + glucose < Maltose + Had lactose senthase Glucose + galactose > lactose + H28 sucrose sunthase Glucose + fructose- Sucrose + H20 Maltuse, or malt sugar is obtained from starch and is found in , germinating grains ↳ When maltose is hydrolyzed by yeast enzymes , glucose is obtained which , can undergo fermentation to give ethanol. In the Haworth structure of a disaccharide a , glycosidic bond connects two monosaccharides glycosidic bond forms groups of carbons In maltose a between the -of 1 and 4 of - , two a-D-glucose molecules with a loss of a water molecule. ↳ This bond is designated as an -1) linkage to show that alpha-of an group on carbon 1 is joined to carbon 4 of the second glucose molecule Because the second glucose molecule still has a free-on group on Carbon 1 it can form an - , open chain , which allows maltuse to form both a and B isomers. The open chain provides aldehyde group that can be oxidized making maltose reducing - an , a sugar  Lactose milk sugar is a disaccharide found in milk and milk products. , , The bond in lactose is a B(1-4) glycosidic bond because the -oh group on carbon - - 1 Of B-D galactose forms a glycosidic bond with the oh group on carbon t of a D-glucose molecule. Because D-glucose still has a free -OH group on Carbon 1 it can form an open chain which - , , allows lactose to form both a and isomers. The open chain provides an aldehyde group that can be oxidized making lactose a - , reducing Sugar - When a person does not produce sufficient quantities of the enzyme lactase , which is needed to hydrolyze lactose it remains undigested, when it enters the colon. Then Bacteria in the colon digest the lactose in a fermentation process that - creates larde amounts of gas including carbon dioxide and methane which causes , bloating and addominal cramps. Sucrose consists of an a-D-glucose and a B-D-fructose molecule joined by an a , B(1-2) glycosidic bond. - unlike maltose and lactose the glycosidic bond in sucrose is between Carbon 1 of glucose and - , Carbon 2 of fructose. ↳ sucrose cannot form an open chain and cannot be oxidized. Sucrose cannot react with Benedicts reagent and is not a reducing sugar  13 7. Polysaccharides A polysaccharide is a polymer of many monosaccharides joined together. - four important polysaccharides are : amylose 3 · · amylopectin They are all polymers of D-glucose that differ only in the cellulose type of glycosidic bonds · and the amount of in branching glycogen the molecule. · Starch-astorage form of glucose in plants is found , in rice , beans a cereals ↳ Starch is composed of2 kinds of polysaccharides amylose - and amylopectin. Amylose - makes up about 20% of starch , consists of 250 to 4000 d-D-glucose molecules connected by all-c)-glycosidic bonds in a continuous chain. a polymers of amylose are actually coiled in helical fashion Amylopectin- makes up about 80% of starch is , a branched chain polysaccharide. Like amylose , the glucose molecules are connected by a (lea) glycosidic bonds. However - , at about every 25 glucose units , alucose molecules attached there is a branch of by an a (1-6) glycosidic bond between Carbon 1 of the branch and Carbon 6 in the main chain. starches hydrolyze in water and acid to give smaller saccharides called defrins , Detrins hydrolyze to maltose and finally glucose In our bodies these complex carbohydrates digested by the enzyme amylase (saliva - , are and maltuse (intestine). The glucose obtained provides about 50% of our nutritional calories Glycogen , animal starch , is polymer of glucose that is stored in the liver a and muscle of animals. It is hydrolyzed in our cells at a rate that maintains the blood level of glucose and provides energy between meals.The structure ofalycogen is very similar to that of amylopectin found in plants except that glycogen is more highly , branched In glycogen the glucose units are joined by all-c) glycosidic bonds and -. , , branches occuring about every 10 to 15 glucose units attached by all-6)-glycosidic bonds. Cellulose is the major structural material of wood and plants. Cotton is almost pure cellulose. In cellulose glucose molecules form , a long unbranched Chain similar to that of amylose. However , the glucose units in cellulose are linked by B11-r-glycosidic bonds. The cellulose chains do not form Coils like amylose but are aligned in parallel rows that are held in place by hydrogen bonds between hydroxyl groups in adjacent chains making , cellulose insoluble in water. This gives a rigid structure to the cell walls in wood and fiber that is more resistant to hydrolysis than are the starches. Humans have an enzyme called d-amylase in saliva and pancreatic juices that hydrolyzes the all-1) glycosidic bonds - of starches but not the , B(1 + c)-glycosidic bonds of cellulose. Thus humans cannot , digest cellulose but some animals can ,  14 1. Carboxylic Acids Carboxylic acids are weak acids. sour/tart taste - - produce hydronium ions (H30t) in water - neutralize bases In a carboxylic acid , the carbon atom of a carbonyl group is attached to a hydroxyl group that forms a carboxyl group. C 0 = In a carboxylic acid , the carbon atom of a carbonyl group is attached to a hydroxyl group that forms a carboxyl group. - OH The carboxyl functional group may be attached to an alkyl group or an - aromatic group. some ways to represent the carboxyl group in carboxylic acid IUPAC Names of Carboxylic Acids replaces the e of the corresponding alcane name with oic acid. - If there are substituents the carbon chain is numbered beginning with the - , carboxyl carbon The simplest aromatic carboxylic acid is named benzoic acid With. the carboxyl Carbon bonded to carbon I , the ring is numbered in the direction that gives substituents the smallest possible numbers.  Common Names of Carboxylic Acids -use the prefixes form acet propin : , , , butyr 14 2. Properties of Carboxylic Acids carboxylic acids are among the most polar organic compounds because their - functional group consists of two polar groups : Dhydroxyl group (-on) Carbonyl group (c 0) 2) = - The-oh group is similar to the functional group in alcohols , and the =0 double bond is similar to that of aldehydes and betones Solubility in water - Carboxylic acids with 1-5 carbons are soluble in water because the carboxyl group forms hydrogen bonds with several water molecules. carboxylic acids having more than 5 carbons are not very soluble in water - Acidity of Carboxylic Acids - when a carboxylic acid dissociates in water , a hydrogen ion is transferred to a water molecule to form a negatively charged Carboxylate ion and a hydronium ion (H30 ). + - Carboxylic acids are more acidic than most other organic compounds 3 however , they are weak acids because 1% of the carboxylic acid molecules dissociate in water. carboxylic acids can lose hydrogen ions because the negative charge of the - carboxylate anious is stabilized by the two oxygen atoms.  # · Neutralization of Carboxylic Acids - Because carboxylic acids are weak acids they are , completely neutralized by strong bases such as NoH and KOH The products carboxylate salt and water - are a - The carboxylation is named by replacing the is acid ending with ate. carboxylate salts are ionic compounds with strong attractions betweenpositively charged metal ions such as Lit Nat , and let and the , negatively charged carboxylate ion. carboxylate salts are : solid at room temp - have high melting point - usually soluble in water -  14 3 Esters. - When a carboxylic acid reacts with an alcohol an ester and water are, produced when the -H of the carboxylic acid is replaced by an alkyl group. - fats and oils are esters of glycerol and fatty acids , which are longchain carboxylic acids Esterification ↳ an ester is in the produced when a carboxylic acid and an alcohol react presence of an acid Catalyst (usually Hason) and heat. In esterification , the -on group from the Carboxylic acid and the -H from the alcohol are removed and combine to form water. - An excess of the alcohol is used to shift the equilibrium in the direction of the formation of the ester product. pentyl ethanoate can be prepared using ethanoic acid and 1-pentanol. Ester synthesized from butanoic acid and methanol z balanced equation of formation  Naming Esters The name of an ester consists of two words derived from the name of the - , i) alcohol indicates the alkyl part from the alcohol - 2) acid-the name of the carboxylate from the carboxylic acid ↳ luPAC names use the luPAC names of acids while the Common name uses the common , name of the acids. When given by Separating the ester bond to identify the alkyl an ester , start part of the alcohol and the carboxylate part from the acid. Then, name the ester as an alkyl carboxylate Examples ofIUPAC and common names of some typical esters small esters are volatile so we , can smell them and they are soluble in , water , so we can taste them.  14 4. Hydrolysis of Esters Esters undergo hydrolysis when they react with water in the presence of an acid or base. Therefore hydrolysis is the reverse of the esterification reaction. , , Acid Hydrolysis of Esters water reacts with an ester in the presence of strong acid usually H SO , - a , c or HC) , to form a carboxylic acid and an alcohol A water molecule provides the -oh convert the carboxyl group of the group to - ester to a carboxyl group. When hydrolysis of biological esters occurs in the cells an enzyme replaces the - , acid as a catalyst Base Hydrolysis of Esters (Saponification) When an ester undergoes hydrolysis with a strong base Such as Naot or RoH, the products are the carboxylate salt and the corresponding alcohol. example : ↳ The the carboxylate salt, hydrolysis of ethyl acetate with NaoH gives sodium acetate and , ethyl alcohol  14 5 Amines. Amines and Amides are organic compounds that contain nitrogen. Naming and Classifying Amines Amines are derivatives of ammonia (NH) in which one or more hydrogen atoms - , are replaced with alkyl or aromatic groups - In Methylamine , a methyl group replaces one hydrogen atom in ammonia - The bonding methyl groups gives dimethylamine of two the three methyl groups in trimethylamine replace all the hydrogen atoms in ammonia - The common names of amines are often used when the alkyl groups bonded to the nitrogen atom are not branched 6 Then the alkyl groups are listed in alphabetical order 6 The prefixes di and tri are used to indicate two and three idential substituents Amines are classified by counting the number of carbon atoms directly bonded to the nitrogen atom In a primary (1 ) amine the nitrogen atom is bonded to one alkyl group - % , - In a secondary (2) amine the nitrogen, atom is bonded to two allyl groups In a tertiary (3) amine the nitrogen atom is bonded to three alleys groups - ,  Line-AngleFormulas for Amines we show the hydrogen atoms bonded to the N atom - Aromatic Amines b use the name aniline Alkyl groups attacked to the nitrogen of aniline are named with the prefix ~- followed - by the allyl name Solubility of Amines in water Because amines contain a polar N-H bond , they form hydrogen bonds with water. In primary (1 ) amines NHL can form more hydrogen bonds than the Secondary (2% - % - , amines. A tertiary (30 amine has no hydrogen on the nitrogen atom can form , only , hydrogen bonds with water from the Natom in the amine to the H of a water molecule. In alcohols the smaller amines including tertiary ones are soluble because they - , , , form hydrogen bonds with water. However in amines with more than six carbon atoms the effect of , , hydrogen bonding is diminished. Then the nonpolar hydrocarbon chains of the amine decreases its solubility in water.  Amines React as Bases in water Ammonia (NH3) acts as a Bronsted-Lowry + base because it accepts H from water to produce an ammonium ion (NHy) and a hydroxide ion (OH) NH3 + H20 : 'NHyt + OH Ammonium Hydroxid a Ammonia In water amines act as , Bronsted-Lowry bases because the lone electron pair on the nitrogen atom accepts a hydrogen ion from water and produces alkylammonium and hydroxide ions Reaction of a primary Amine with water Reaction of a Secondary Amine with water Ammonium salts In a neutralization reaction an amine acts as a base and reacts with an acid , to form an ammonium salt. + The lone pair of electrons on the nitrogen atom accepts H from an acid to give - an ammonium salt ; no water is formed. - An ammonium salt is named by using its alklylammonium ion name , followed by the name of the negative ion. Neutralization of an Amine  Properties of Ammonium salts Ammonium Salts are ionic compounds with strong attractions between the pos charged ammonium ion and an anion , usually chloride. Ammonium salts are : ↳ solids at room temperature ↳ Odorless ↳ soluble in water/body fluids Where an ammonium salt reacts with a such as Naol it is strong base , converted back to the amine , which is also called the free amine/free base CH3-NHsCl + NaOH-CHa-NHz + NaCl + HiO 14 6. Acides The amides are derivatives of carboxylic acids in which a nitrogen group replaces the hydroxyl group Preparation of Amides An amide is produced - in a reaction called amidation in which , a carboxylic acid reacts with ammonia or a primary or secondary amine. ↳ A molecule of water is eliminated and and amine the , fragments of the carboxylic acid molecules join to form the amside much like the formation of , an ester. - Because a tertiary amine does not contain a hydrogen atom , it cannot undergo amidation  Naming Amides In theIUPAC and common names for amides the oic acid , or ic acid from the corresponding carboxylic acid name is replaced with amide when alkyl groups are attached to the nitrogen atom , the prefix N - or N , N- precedes the name of the amide depending , on whether there are one or two groups. S ~ solubility of Amides in water - The amides with one to five carbon atoms are soluble in water because they can hydrogen bond with water molecules In amides with more than five carbon atoms the effects of hydrogen bonding is - , diminished as the longer carbon chain decreases the solubility of an amide in water Hydrolysis of Amides Amides undergo hydrolysis when water is added to the amide bond to split the molecule. ↑ When an acid is used the hydrolysis - , products of an amide are the carboxylic acid and the ammonium salt - In base hydrolysis , the amide produces the carboxylate salt and ammonia or an amike  An ester can be hydrolyzed by H2SO4 and H20 to produce a carboxylic acid and - an alcohol An ester can be hydrolyzed by Naot andz0 to produce and a carboxylate an - alcohol - An amide can be hydrolyzed by lot and H20 to produce a carboxylate and an amine - An amide can be hydrolyzed by H2SOy and H2O to produce a carboxylic acid and an ammonium salt.  15 1. Lipids Lipids are a family of biomolecules that have the common property of being soluble in organic solvents but not in water. - Typically , the lipid content of a cell can be extracted using a nonpolar solvent such , as ether or chloroform - Lipids are an important feature in cell membranes and steroid hormones Types of Lipids ↳ there are specific structures that distinguish the different types of lipids. Lipids such as waxes , triacylglycerols glycerophospholipids , , and sphingolipids hydrolyzed to give fatty are esters that can be along acids with other molecules. Triacylglycerols and glycerophospholipids contain the alcohol glycerol - sphingolipids contain the amino alcohol sphingosine. - Steroids have a completely different structure they do not contain , fatty acids and cannot be hydrolyzed. - They are characterized by the steroid nucleus of four fused carbon rings 15 2. Fatty Acids A fatty acid contains a long unbranched carbon chain with , a carboxylic acid group at one end Although the carboxylic acid part is hydrophilic the carbon chain. , long hydrophobic makes fatty acids insoluble in water. enaturally occuring futty acids have an even number of carbons (12-20 usually  example of fatty acid : lauric acid a 12-carbon acid chain found in coconut oil - -shorthand notation description is 12: 0 ; 12 for #of carbons O , for # of double bonds Saturated Fatty acid (SFA) : contains only carbon-carbon single bonds, which make the properties of a long-chain fatty acid similar to those of an alcane unsaturated fatty acid(UfA) contains carbon-carbon : one or more double bonds. monounsaturated fatty acid (MUFA) has a long carbon chain that has one : double bond , making it similar to the properties of an alkene polyunsaturated fatty acid (PUFA) : has at least two carbon-carbon double bonds. Present in : Melting point : P · Lauric acid - 12 : 0 - Coconut-44 % MMOH Myristic acid-16 acide Palmitic 14 : 0 : 0 > - > - Nutmeg-55 Palm > - 63% - Stearic acid - 18 : 0 - Animal fat-69 % - E palmitoleic acid-16 : 1 Oleic acid-18 1 - Olives pecan : - , Butter -0 C , grapeseed ° - 14 C ° Linnic : Linoleic acide 18 : 2- Soybean safflower sunflower--5 , , C acide183 corner Arachidonic acid 20 : 4-meat eggs fish 50 C ° - -- , ,  Cis and Trans Isomers of Unsaturated Fatty Acids The cis structure is the more prevalent isomer found in naturally occuring unsaturated fatty acids. - In the cis isomer the carbon chain has , a "kink" at the double bond site. - The trans isomer of oleic acid claidic acid is a, , straight chain without a kink at the double bond site. The human body is capable of synthesizing some fatty acids from carbohydrates or other fatty acids.However humans cannot synthesize , Sufficient amounts of polyunsaturated fatty acids such as linoleic acid, linolenic acid and arachidonic , acid. ↳ Because they must be obtained from the diet , they are known as essential fatty acids (EfAs) Physical Properties of Fatty Acids In USFA molecules The saturated fatty acids fit closely together in a regular pattern which allows - , , cannot fit closely many dispersion forces between the carbon chains. together , resulting4 These normally weak forces of attraction become important when molecules In lower melting pt. Of fatty acids are close together. - As a result , a significant amount of energy and higher temperatures are required to separate the fatty acids before melting occurs. - As the length of the carbon chain increases more interactions occur , between the fatty requiring higher acids , temperatures to melt. saturated fatty acids are usually solids at room temperature. - - In unsaturated fatty acids , the cis double bonds cause the carbon chain to bend kink or , giving the molecules an irregular shape. As a result unsaturated fatty acids cannot stack as closely as saturated fatty - , acids and thus have fewer , dispersion forces between carson chains. -consequently , less energy is required to separate these molecules , making the melting points of unsaturated fatty acids lower than those of saturated futty acids. Most unsaturated fatty acids are liquids at room temperatures - Prostaglanding 6 hormone-like substances produced in small amounts in most cells of the body. also known as eicosanoids are formed from arachidonic acid the polyunsaturated fatty - , , acid with 20 carbon atoms. -prostaglandin E" (soluble in ether) "Prostaglandin f" (soluble phosphate butter) in The various kinds of substituents attached prostaglanding differ by the - to the substituents attacked to the five-carbon ring. Prostaglandin E(PGE) has betone group on Carbon 9 - a Prostaglandin F(PGF) has a hydroxyl group - ↳ The number of double bonds is shown as a subscript 1 or some prostaglanding increase blood pressure and others lower blood pressure , OthersStimulate contraction and relaxation in the smooth muscle of the uterus. - The treatment of pain fever and inflammation is based on ihibiting - , , the enzymes that convert arachidonic acid to prostaglandins several nonsteroidal anti-inflammatory drugs (NSAID) , such as aspirin, - block the production of prostaglanding and in doing so decrease pain and inflammationand reduce fever. 15 3 Waxes and Triacylglycerols. A wax is an ester of a long-chain fatty acid and a long-chain alcohol, each containing from 19 to 30 Carbon atoms. WAX - Ester bondy & Fatty acid "-o Long-chain alcohol Triacylglycerols In the body , fatty acids are stored as triacylglycerols also called triglycerides, , which are friesters of Glycerol (a trihydroxy asconol) and fatty acids. The general formula of triacylglycerol follows : In a triacylglycerol three hydroxyl groups ofglycerol form ester bonds with the , carboxyl groups of three fatty acids. For example glycerol and three molecules of stearic , acid form a triacylglycerol. In the name glycerol is named glyceryl and the fatty acids are named as - , carboxylates. ↳ for example stearic acid is named as stearate which , , gives the name glyceryl tristearate. The common name of this compound is tristearin. In a triacylglycerol , three hydroxyl groups of glycerol form ester bonds with the carboxyl groups of three fatty acids. ↳ In the name and acids are named as , glycerol is named glyceryl fatty carboxylates. for example , glycerol and three molecules of stearic acid form a triacylglycerol Stearic. acid is named is named as stearate which , gives. the name glyceryl tristearate 6 this compound is tristear in The common name of Most naturally occuring triacylglycerols contain glycerol bonded to two or three different fatty acids typically : palmitic acid oleic acid linoleic acid , , , a stearic acid , mixed triacylglycerol made from : Stearic acid · · oleic acid · palmitic acid Draw the condensed structural formula for glyceryl tripalmitoleate (tripalmitolein) : Step 1) Draw the condensed structural formulas for glycerol and the fatty acids Step 2) form ester bonds between the hydroxyl groups on glycerol and the Carboxyl groups on each fatty acid line angle formula for the triacylglycerol containing three molecules of myristic acid (14 0) : Triacylglycerols are the major form of energy storage for animals Melting Points ofFats and Oils A fat is a triacylglycerol that is solid at room temperature , and it usually comes from animal sources (meat , butter , cheese An oil is a triacylglycerol that is usually a liquid at room temperature and is obtained from a plant source saturated fatty acids have higher melting points than unsaturated fatty acids because they back together more tightly. ↳ The metting points of animal fats are higher than those of vegetable oils 15 4 Chemical Properties of. Triacylglycerols The chemical reactions of triacylglycerols involve the hydrogenation of the double bonds in the fatty acids and the hydrolysis and , saponification of the ester bonds between glycerol and the fatty acids. Hydrogenation reaction hydrogen gas is bubbled : through the heated oil typically in the presence of a nickel catalyst. As a result Hatums add to one or more carbon- , carbon double bonds to form Carbon-carbon single bonds.  glyceryl trioleate becomes the saturated fat glyceryl tristearate Hydrolysis Triacylglycerols are hydrolyzed (split by water) in the presence of strong acids such as Hel or H2SOc or ,digestive enzymes called lipases. 6 The products of hydrolysis of the ester bonds are alycerol and three fatty acids. 6 The polar glycerol is soluble in water but the fatty , acids with their long hydrocarbon chains are not Saponification occurs when a fat is heated with a strong base such as Naol to form glycerol and the sodium salts of the fatty acids which is soap. , NaOH used a solid Soap is produced that can be molded : - ROH used produces a softer liquid Soap - : , An oil that is polyunsaturated produces a softer soap - 15 5 Phospholipids. The phospholipids are a family of lipids similar in structure to triacylglycerols ; they include glycerophospholipids and sphingomyelins. In a glycerophospholipid two fatty acids form ester bonds with the first and : second hydroxyl groups of glycerol. The third hydroxyl group forms an ester with phosphoric acid which forms another phosphoester bond with an amino , alcohol In a Sphingomyelin , sphingosine replaces glycerol  Amino Alcohols Three amino alcohols found in glycerophospholipids are choline serine and , , ethanolamine. ↳ In the body , at a pH of 7 4 , these. amino alcohols are ionized Lecithins and cephaling are two types of glycerophospholipids. b & contain contain choline ethanolamine and sometimes serine. , Glycerophospholipids contain both polar and nonpolar regions which allows them , to interact with both polar and nonpolar substances. "the head" - the ionized amino alcohol and phosphate portion is polar and strongly attracted to water ! "tails" -> the hydrocarbon chains of the two fatty acids are the two nonpolar "tails" of the glycerophospholipid which are soluble in other nonpolar substances , (mostly lipids) Phospholipases-enzymes that catalyze the hydrolysis of the fatty acid on the center carbon of glycerophospholipias in red blood cells. lysophospholipids-cause breakdown of the red blood cell membranes Sphingosine , found inSphingomyelins and other sphingolipids , is a long chain amino alcohol. In a sphingomyelin , the amine group of sphingosine forms an amide bond to a fatty acid and the hydroxyl group forms an ester bond with phosphate , which forms another phosphoester bond to choline or ethanolamine. & the sphingomyelins are abundant in the white matter of the myelin sheath. In multiple sclerosis sphingomyelin is , lost from the myelin sheath and ,. Scars form will deteriorate on the neurons and impair the transmission of nerve signals. Asphingomyelin found in eggs contains sphingosine palmitic , acid (16 : 0) phosphate and choline Cionized , ,. condensed structural formula :  15 6 Steroids : Cholesterol Bile Salts and Steroid Hormones. , , Steroids : are compounds containing the steroid nucleus which consists of three , cyclo- nexane rings and one cyclopentance ring fused together. - The four rings are designated A, B C ,D , The carbon atoms are numbered beginning with the carbons in Ling A , and in steroids - like cholesterol , ending with two methyl groups Cholesterol : most important and abundant steroid in the body.It is a sterol because it contains an oxygen atom as a hydroxyl group (-0t on carbon 3. ↳ has a double bond between carbon 5 and Carbon 6 methyl groups at Carbon 10 and 13 and , , a carbon chain at carbon 17 In Other steroids the oxygen atom forms a carbonyl group (C 0) at carbon 3. - = , Cholesterol is a component in found in : - cellular membranes myelin sheath - brain and nerve tissues - - liver and bile salts found on skin - becomes Vitamin D with sunlight ↳ In the advenal gland it synthesizes steroid hormones , 6 liver synthesizes it for the body from fats carbohydrates and proteins , , h Additional cholesteral is obtained from meat milk, and eggs. None in , veggies/plants Bile salts Are synthesized from cholesterol in the liver and stored in the gallbladder When bile is secreted into the small intestine , the bile salts mix with the water-insoluble fats and - oils in our diets. The bile salts with their nonpolar and polar regious act like scaps , breaking down large - globules of fat into smaller droplets (those. react with lipases which are the enzymes that , digest fat. The pile salts help with absorption of cholesterol into the intestinal mucosa - -calistines form in the gallbladder when cholesterol levels are high  structure of Bile Salts S Lipoproteins Transporting Lipids : In the body , lipids must be moved through the bloodstream to tissues where they are stored used for energy or used to makehormones , , 6 They are made more soluble by combining them with phospholipids and proteins to form water-soluble complexes called lipoproteins 3 Aspherical lipoprotein particle surround nonpolar lipids with polar lipids and protein for transport to body cells There are a variety of lipoproteins which differ in density , , lipid composition and, function. The density of the lipoproteins increases as the percentage of protein increases. chylomicrons - -very-low-density lipoprotins (VLDLs) low-density lipoprotins (LDL) 3 - transport cholesterol -high-density lipoprotins (HDL) - The LDL carries cholesterol to the tissues where it can be used for the sunthesis of tell membranes and steroid hormones. When the LDL exceeds the amount of cholesterol needed by the tissues the LDL deposits - , cholesterol in the arteries (plaque) - restricts blood flow risk of heart , disease/attack. "This is why LDL is the "bad" cholesterol  The HDL picks up cholesterol from the tissues and carries it to the liver where it , can be converted to bile salts which are eliminated from the body. , This is why HDL is called the "good" cholesterol Steroid Hormones Hormones are chemical messenders that : communication system in body. serve as a The steroid hormones which include the sex hormones and the adrenocortical hormones, , are closely related instructure to cholesterol and depend on cholesterol for their synthesis. Male sex hormones : testosterone and androsterone ↳ promote growth of muscle and facial hair , and maturation of sex organs and of sperm Group female sex hormones estrogens of : ↳ direct the development of female sexual characteristics Adrenal Corticoids The advenal glands produce a large number of compounds known as the corticosteroids. - cortisone : increases the blood glucose level and stimulates the synthesis of glycogen in the liver. - Aldosterone : regulation of electrolytes and water balance by the kidneys Cortisol : is released under stress to increase blood sugar and regulate carbohydrate fat and - , , protein metabolism synthetic corticosteroid drugs such as prednisole are derived from cortisone medicine -  15 7 Cell Membranes. The membrane of a cell separates the contents of a cell from external fluids. ↳ Semipermeable : nutrients can enter cells and waste products can leave , cell membranes made of : glycerophospholipids and sphingolipids In a cell (plasma) membrane , two layers of phospholipids are arranged with their hydrophilic heads at the outer and inner surfaces of the membrane and their , hydrophobic tails in the center. 6 This double layer arrangement of phospholipids is called a lipid bilayer Fluid Mosaic model Most of the phospholipids in the lipid bilayer contain unsaturated fatty acids and they , do not fit closely together. has a result , the lipid bilayer is not a ridid fixed structure but one that is dynamic and fluid like , , , bilayer contains proteins carbohydrates and cholesterol molecules. - , , - Proteins known as peripheral proteins emerge on just one of the surfaces outer , or inner. The integral proteins extend through the entire lipid bilayer and appear on both surfaces some proteins and lipids on the outer surface are attached to carbohydrates - ↳ carbohydrate chains responsible for cell recognition and communication Because cholesterol molecules are large and rigid they reduce the flexibility of the lipid bilayer - , and add strength to the cell membrane Diffusion (passive)Transport Molecules can diffuse from a higher concentration to a lower concentration If concentration is greater outside the cell than inside they diffuse into the cell - , Facilitated Transport Proteins that extend from one side of the bilayer membrane to the other provide a channel through which certain substances can diffuse more rapidly than by passive diffusion to meet cellular needs. These protein channels allow transport of chioride ion (C1), bicarbonate ion (HCOs] , and glucose molecules in and out of the cell. Active Transport certain ions such as let , Nat , and Ca more across a cell membrane against their concentration gradients. ↳ for example the let concentration is greater inside a cell and the Nat concentration is , , greater outside. However in the conduction of nerve impulses and contraction of muscles let , , moves inside the cell and Nat moves out by a process known as active , transport. 16 1 Proteins and Amino Acids. Proteins are formed when smaller molecules called amino acids link together in a chain. Amino Acids There are 20 amino acids commonly found in the proteins of living organisms. Every amino acid has a central carbon atom called the a carbon bonded to twoa functional groups : an ammonium group)-NHst) and a carboxylate group (200). The a carbon is also bonded to a hydrogen atom and a side chain called an R group. 3 The differences in the 20 amino acids are due to the characteristics of the unique R group Classification of Amino Acids ↳ classify amino acids based on their specific Rgroups , which determines their properties in aqueous solution The nonpolar amino acids have hydrogen , alkyl , or aromatic R groups , which make them hydrophobic ("water fearing")  The polar amino acids have R groups that interact with water which makes them , hydrophilic ("water loving" ↳ There are three groups of polar amino acids - The R groups of polar neutral amino acids contain hydroxyl (-OH) , thios (-SH), or amide (-CONH2) groups. The R group of a polar acidic amino acid contain a carboxylate group (coof. - - The R group of a polar basic amino acid contains an amino group which ionizes , to give an ammonium ion.  16 2 Proteins : Primary Structure. A peptide bond is an amide bond that forms when the-Coo-group of one amino acid reacts with the C-NHzt) group of the next amino dcid. 3 The linking of two or more amino acids by peptide bonds forms a peptide. - O and 2H removed to produce water Two amino acids form a dipeptide Three amino acids form a tripeptide four amino acids form a tetrapeptide A chain of five amino acids is pentapentide a Longer chains of amino acids are polypeptides Amidation reaction for the formation of a dipeptide formed between : glycine , and alanine , glycylalanine - (Gly-Ala GA) , After HzO is produced , glycine has a free(unbonded) NHst group - , which makes it the N-terminus In the peptide the amino acid alanine has. , , , a free (unbonded) - Coo group , which makes it the C-terminus. The dipeptide forms when the Carbonyl group in glycine bonds to the N atom in the - - NH3 group of alanine Naming Peptides Peptides are drawn and named from N-terminus to C-terminus. - with the exception of the amino acid at the C-terminus the , names of all the other Amino acids in a peptide end with y1. for example , a tripeptide consisting of alahine at the N-terminus , glycine , and serine at the C-terminus is named as one word : alanylglycylserine. the order of amino acids in the peptide is often written as the sequence of three-letter or - one letter abbreviations. Primary structure of a protein A protein is a polypeptide of So or more amino acids that has biological activity. is the particular sequence of amino acids held The primary structure of a protein together by peptide bonds from N-to C-terminus > - R groups are colored red > The atoms colored black are known - as the backbone of the peptide or protein , which is the repeating sequence of the N in the ammonium group the from , a carbon , and the and the C from the carboxylate group (-N-C-CN-c-C- N-C-C) In the primary structure of human insulin there , are I polypeptide chains. In Chain A there are 21 amino acids and chain B has 30 amino acids. , , ↳ chains held together by disulfide bonds formed by the thiol groups of the cysteine amino acids in each of the chains. Sample Problem : Draw the structure and give the name for the tripeptide fly-Ser-Met Step 1) Draw the structure for each amino acid in the peptide N-terminus , starting with Step 2) Remove the 0 atom from the carboxylate group of the N-terminus and two H atoms from the ammonium group in the adjacent amino acid. Repeat. Step 3) Use peptide bonds to connect the amino acids Naming : The tripeptide is named by replacing the last syllable of each amino acid name with y1 starting , with the N-terminus. The C-terminus retains its complete amino acid name N-terminus glycine is named glycylserine is named sery C-terminus methionine keeps its full name The tripeptide is named glycylsevylmethionine 16 3 Proteins :. Secondary Tertiary , , and Quaternary Structures The secondary structure of a protein describes the type of structure that forms when the atoms in the backbone of a protein or peptide form hydrogen bonds within a polypeptide or between polypeptide chains. ↳ most common secondary structure are the alpha helix and the beta-pleated sheet. Alpha Helix Hydrogen bonds form between the oxygen of the C 0 groups and the = hydrogen of the N-H of the amide bonds in the next turn of the helix groups a. The formation of many hydrogen bonds along - the polypeptide chain gives the characteristic helical shape of a spiral staircase All of the R of the different amino groups acids extend to the outside of helix.  Beta-pleated Sheet Hydrogen bonds form between the oxygen atom atoms in the Carbonyl groups in one section of the polypeptide chain and hydrogen atoms in the , the N-H groups of the amide bonds in a nearby section of the polypeptide Chain The hydrogen bonds account for the strength and durability of proteins - Collagen -Makes up as much as one third of all protein in vertebrates The strong structure of collagen is a result of three like braid polypeptides woven together a - to form a triple helix. Strength depends on the hydroxylation of proline and lysine. (Vitamin Tertiary structure Involves attractions and repulsions between the R groups of the amino acids in the polypeptide chain. - As interactions occur between different parts of the peptide chain , segments of the chain twist and bend until the protein acquires a specific three-dimensional snape - The tertiary structure of a protein is stabilized by interactions between the R groups of the amino acids in region of the polypeptide chain and the R one