BIOCHEMISTRY First Year Past Paper PDF

BIOCHEMISTRY 1ST YEAR KHALED ELSHAMY CONTENTS THEORTICAL CARBOHYDRATE 1 LIPID 21 PROTEIN 35 ENZYMES 46 QUESTIONES MONOSACCHARIDES 66 DISACCHARIDES 74 POLYSACCHARIDES 77 LIPID 83 PR...

BIOCHEMISTRY 1ST YEAR KHALED ELSHAMY CONTENTS THEORTICAL CARBOHYDRATE 1 LIPID 21 PROTEIN 35 ENZYMES 46 QUESTIONES MONOSACCHARIDES 66 DISACCHARIDES 74 POLYSACCHARIDES 77 LIPID 83 PROTEIN 91 ENZYMES 99 CARBOHYDRATE Khaled-Elshamy Introduc)on - The nutrient your body needs to promote growth and development and regulate bodily processes can be divided into: Macronutrient Micronutrient - The nutrient your body needs in - The nutrient your body need in large amount. smaller amount. eg: CHO – fat – protein - Used eg: vitamins and minerals as a soruce of energy - Help our body to be healthy and to digest macronutrient CARBOHYDRATES Def: They are organic molecules contain C – H – O The laBer two elements (H – O) are present in the same raEo as water 2:1 They are aldehyde derived or keton derived from poly hydric alcohols or any substances derived from them. - Classiﬁca)on of CHO * According to NO. of sugar units: Monosaccharide: formed from 1 sugar unit (Glucose) Oigosaccharide: formed from 2-10 suger units (Sucrose – Raﬃnose) Polysaccharide: formed from more than 10 suger unites (Starch) - Monosaccharide: They are the simplest units of CHO, on hydrolysis they can not give a simpler form. - Their general formula CnH2nOn=(CH2O)n 2 Khaled-Elshamy Classiﬁca)on of Monosaccharide According to: No. of carbon Func:onal group Both 3c Triose Aldo sugar contain – Aldo or ketotriose 4c Tetrose CHO Aldo or 5c Pentose Keto sugar contain- ketotetrose 6c Hexose C=O Aldo or 7c Heptose ketopentose Aldo or ketohexose Aldo or ketoheptose Trioses Tetroses Pentose Hexsose 3 Khaled-Elshamy Importance of CHO: CHO are the most abundant organic molecules found in nature. Important source of energy each 1g 4Kcal. Structural component of many organisms such as cell wall of bacteria. Diseases associated with Glucose metabolism:- (DM – galactosemia – lactose intolerance) Monosaccharide of biological importance: - Ribose and Deoxyribose: Enter in the structure of RNA & DNA. Enter in the structure of ATP – GTP & high energy phosphate compounds. Ribose phosphate and Ribulose phosphate intermediate in pentose phosphate pathway. - Arabinose: A consEtuent of Glycoprotein in plants. - Lyxose: Isolated from human heart muscle - Xylulose: Intermediate in uronic acid pathway. - Glucose: Blood sugar Sugar of grape. Also (corn sugar) The main metabolic fuel for Essue eg:(Brain-Liver) - Fructose: sugar of semen sugar of fetal blood Metabolized in liver to Glucose - Galactose: Synthesised in mammary gland to enter in synthesis of lactose in milk. - Mannose: A consEtuent in Glycolipid and Glycoprotein. 4 Khaled-Elshamy Isomerism of Monosaccharide Isomers: They are compounds have the same chemical formula but diﬀer in the spaEal conﬁguraEon. Asymmetric carbon: carbon atom that is aBached to four diﬀerent groups or atoms. No. of isomers = 2n n= No. of asymmetric carbon No. of asymmetric carbon in aldo sugar = No. of carbon atoms – 2 No. of asymmetric carbon in keto sugar = No. of carbon atoms – 3 Q: No. of isomers of Glucose ( Aldo sugar ) n=6-2=4 No. of isomers = 24 =16 Q: No. of isomers of fructose ( keto sugar ) n=6-3=3 No. of isomers = 23 = 8 Stereo isomers 1. Enan$omers (mirror image or D and L forms) 2. Epimers 3. Aldose ketose isomers 4. Anomer 1-Enan)omers: A special type of isomers found in the pairs of structures that are mirror image of each other. The posidons of H and OH are variable at all carbon atoms. Reference carbon: The carbon atom next to CH2OH terminal - If OH Group at which on the right side (D-sugar) - If OH group at which on the lef side (L-sugar) Racemases enzymes interconvert between D and L isomers. - Glyceraldehyde (glycerose) called reference sugar. 2-Epimers: 5 Khaled-Elshamy Isomers have more than asymmetric carbon all are the same but diﬀer in only one carbon Glucose and Galactose are epimers at C4 Glucose and Mannose are epimers at C2 Galactose and Mannose are not epimers (only isomers) Fructose not epimer to Glucose 3-Aldose ketose isomers: Isomers have the same molecular formula but diﬀer in the funcdonal group eg: Glucose and Fructose 4-Anomer: They are isomers obtained from the change at posiEon of the OH group aeached to anomeric carbon. Anomeric carbon: It is asymmetric carbon atom obtained from the acdve carbonyl sugar group C1 in aldoses and C2 in ketoses Found only in ring structure. 6 Khaled-Elshamy Cyclic structure of Monosaccharide - Less than 1% of monosaccharide with 5 or more carbons exist in the open chain (acyclic form) ﬁsher projecdon. - The are predominantly found in (cyclic form) haworth projecdon. Pyran ring: Six membered ring (5C+O) Furan ring: Five membered ring (4C+O) - Aldo hexoses are more stable in pyran ring (Glucose-mannose-galactose) - Keto hexose from furan ring (fructose) To transfer from acyclic form to cyclic form:- 1-OH groups found on the right side in open chain become below in cyclic form. 2-OH groups found on lef side in open chain become above in cyclic form. Cycliza)on of Glucose - If the OH group aeached to anomeric carbon which found above in cyclic form it’s called β sugar. - If the OH group aeached to anomeric carbon which found below in cyclic form it’s called α sugar. Anomeric carbon before cyclizadon is a symmetric carbon but afer cyclizaEon become Asymmetric carbon. - Physical proper9es of monosaccharide All monosaccharide soluble in water. Op:cal ac:vity: the ability of substances to deviate mono chromic polarized light to the right dextrorotatory or lef levorotatory. 7 Khaled-Elshamy The opdcal acdvity of given substances (speciﬁc rotadon) is measured by polarimeter. All compounds with asymmetric carbon are opdcally acdve except dihydroxyacetone as it haven’t asymmetric carbon. Speciﬁc rotadon of glucose is +52,5 so Called dextrose and Fructose -92 so Called levulose. Some enanEomers rotate polarized light to opposite direcdon so when mixed with the same concentraEon the mixture has no opdcal acdvity this is called racemic mixture. Mutarota)on: it’s the spontaneous change in the speciﬁc rotadon of opdcally acdve substance.when freshly prepared soludon of the substance is lef a period of dme. It occurs due to interconversion between α and β anomers. When α-D glucose is dissolved in water, the speciﬁc rotadon is gradually decreased from +112° to +52.5° while in β-D glucose, the speciﬁc rotadon is gradually increased from +19° to +52.5°. Open chain formula is an intermediate during this interconversion. In soludons: α-D glucose is 36 %, β-D glucose is 63 % and open chain 1%. 8 Khaled-Elshamy Chemical Proper)es of Monosaccharide Related to OH group:- 1- Esteriﬁca:on: Alcoholic group of sugar react with acids to form esters. - The most important esters are esters with phosphoric acid. 2- Oxida:on of last primary alcoholic group: - CH2OH oxidaEon gives [uronic acid] eg: Glucose → Glucouronic acid. Galactose → Galactouronic acid. 9 Khaled-Elshamy 3- Forma:on of glycosidic linkage: Monosaccharide can be joined together to form disaccharide or oligosaccharide or polysaccharide or with another molecule such as glycerol-sterol-phenol by Glycosidic linkage. Glycosidic linkage formed by condensadon of OH group of anomeric carbon on the monosaccharide with another OH group of another molecule. 2 Types: N- Glycosidic linkage: if the group on the non CHO molecule to which the sugar is aeached is NH2 group. O-Glycosidic linkage: if the group on the molecule to which the sugar is aeached is OH group. All sugar-sugar Glycosidic linkage are O type linkage. Not all sugar -A.A linkage are N type linkage. Related to C=O group: 1- Oxida:on of CHO group: Mild oxidizing agent: such as (dil HNO3) CHO only oxidized and give aldonic acid. eg: Glucose → gluconic acid & Galactose →galactonic acid. Strong oxidizing agent: such as (conc HNO3) Both CHO and CH2OH oxidized and give aldaric acid. eg : Glucose → Glucaric acid (saccharic acid). Galactose →Galactaric acid (mucic acid). 10 Khaled-Elshamy Key: Oxidadon of CH2OH only Uronic acid Glucose Glucouronic acid Galactose Galactonic acid Oxidadon of CHO only by Aldonic acid Glucose Gluconic acid mild oxidizing agent such as Galactose Galactonic acid dil HNO3 Oxidadon of both CHO and Aldaric acid Glucose Glucaric acid CH2OH by strong oxidzing (saccharic acid) agent such as conc. HNO3 Galactose Galactaric acid (mucic acid) 2-Reduc:on of carbonyl group: The carbonyl group in the sugar is reduced to give the corresponding alcohol. eg: - Glucose → Sorbitol - Galactose → GalacEtol - Glyceraldehyde and dihydroxcyacetone→ glycerol - Mannose → mannitol - Fructose → sorbitol or mannitol The reducdon of aldehyde group gives → primary alcoholic group CH2OH. The reducdon of Keton group gives →secondary alcoholic group CHOH Monosaccharide as reducing agent:- All monosaccharide are strong reducing agents due to precence of free aldehyde or keton group. - Bendict reagent beXer than fehling ? -Because it is more stable,sensiEve and speciﬁc. 11 Khaled-Elshamy Sugar deriva)ves 1- Sugar acids (discussed) 2- Sugar alcohol (discussed) 3- Amino sugar 4- Deoxysugars Amino sugars: - Sugar in which the OH group at C2 is replaced by amino group. - There are N- acetyl derivadves such as N- acetyl glucosamine eg: Glucose → Glucosamine - Galactose → Galactosamine - N- acetyl glucosamine: N of amino group in glucosamine aeached to acetyl group. Deoxysugars: - Sugars which their OH group replaced by H. eg: 2 DeoxyRibose L-Fucose [L-6-DeoxyGalactose] 12 Khaled-Elshamy Disaccharides These are formed by condensadon of 2 molecules of monosaccharide bound together by Glycosidic linkage. General formula:- Cn(H2O)n-1 1-Sucrose:- Structure:- α- D Glucose + β-D Fructose linked by α-1-2 glucosidic linkage OR β- 12fructosidic linkage. Sources:- cane sugar-beet sugar-table sugar. Proper:es:- 1- posidve molish test. 2- No free carbonyl group so it’s Non reducing sugar. 3- It dosen’t reduce fehling or bendict. 4- it can’t form ozazone crystals. 5- Dosen’t show mutarotaEon. - On hydrolysis by dil acids or sucrose(invertase) enzyme it gives glucose and fructose. Invert sugar:- This is a mixture containing equal molecular concentraEon of Glucose and Fructose. It’s called invert because of sucrose before hydrolysis is dextrorotatory (alphaglucose+112 and Beta fructose -92) but afer hydrolysis it becomes levorotatory (Glucose +52,5 and fructose -92) power of levorotadon of fructose > Glucose dextrorotadon. Sources: 1- afer hydrolysis of sucrose. 2- Bee honey (natural source). 2-Lactose:- Structure: α -D Glucose + β -D-Galactose By β 1-4 galactosidic linkage. Sources: milk sugar. Proper:es:- 1- posidve molish test. 2- Contain free carbonyl group so it’s Reducing sugar. 13 Khaled-Elshamy 3- It reduce fehling and bendict. 4- it can’t form ozazone crystals (lactosazone). 5- shows mutarotadon. Human milk has concentradon of 7% lactose. Not fermented by yeast because there is not lactase enzyme in yeast. The only natural source of galactose that enter in galactose that enters in galactolipids which are found in great amount in brain and nerves. Why lactose is the best sugar for baby? 1- not fermented so don’t produce gases to baby. 2- not so sweet so don’t produce nausea. 3- has a mild laxadve eﬀect. Lactose intolerance: it’s a condidon in which people have symptoms such as (abdominal pain-bloadng-diarrhea-gas-nausea) due to decrease the ability of lactase enzyme to digest lactose. Treatment: Avoid dairy product. Milk allergy:- It is an abnormal response of the immune system to diary product. not related to lactose intolerance ( ) 3-Maltose:- Structure:- two molecules of α-D- Glucose linked by α 1-4 glucosidic linkage Sources:- 1- malt sugar. 2-Produced by hydrolysis of starch by amylase enzyme. Proper:es:- 1- posidve molish test. 2- Contain free aldehyde group so it’s reducingsugar. 3- it reduce fehling and bendict. 4- form ozazone crystals (maltosazone). 4-Isomaltose:- Structure:- two molecules of α -D-Glucose linked by α- 1-6 glucosidic linkage. Sources:- during digesEon of starch by amylase enzyme. 14 Khaled-Elshamy Proper:es:- Similar to maltose but hydrolysed by isomaltase enzyme. 5-Celliobiose:- Structure: two molecules of β-D-Glucose linked by β -1-4 glucosidic linkage. Sources: produced by parEal hydrolysis of of cellulose found in plants. 6-Trehalose:- Structure: two molecules of α -D -Glucose linked by α 1-1 glucosidic linkage. -Non reducing sugar. Sources: 1- found in plants, animals and microorganisms. 2- Found in shrimp. 3- Found in insects such as bueerﬂies and bees in which blood sugar is trehalose. Func:on: sweeter and preservadves for food Key: 1- all monosaccharide are reducing sugar. 2- all disaccharide menEoned are reducing sugars except [sucrose-trehalose] non reducing. 3- all polysaccharide are non reducing sugars. Polysaccharide General Formula:- (C6H10O5)n Two types:- Homo-Polysaccharide:- Formed of only one type of sugar. Hetero-Polysaccharide:- Formed from diﬀerent sugar. Homo-Polysaccharide:- Starch:- Structure: It is formed by condensaEon of α Glucose units Starch granules formed of:- 15 Khaled-Elshamy Amylose Amylopec:n - The inner non branching layer that - The outer branching layer that represent 15:20% of the granules. - α- represent 80:85% of the granule. Glucose units linked by α-1- 4 linkage. - α Glucose units linked by α-1-4 - Gives blue color with iodine. linkage and α-1-6 linkage at branching points. - Gives red colour with iodine - Starch granules as whole give blue colour with iodine. Sources:- Cereals-Potatoes-rice-wheat Func:on:- The main source of CHO in diet and Present in plants. Proper:es:- 1- posidve molish test. 2- hydrolysed by headng with dil acids or by amylase enzyme. Dextrins: - They are hydrolydc product of starch. - They have simpler structure than starch. Dextrans: - It’s synthesized from sucrose by the acdon of certain bacteria. - Used as plasma subsdtute in case of haemorrhage and to prevent thrombosis. 16 Khaled-Elshamy Glycogen (animal starch):- Structure:- it’s a polymer of α glucose units as starch but more branched. The main glycosidic bond is α1-4 glucosidic linkage and only at branching points α16glucosidic linkage (similar to amylopecdn). Loca:on:- Liver and muscles Func:on:- The main storage form of glucose in body so it is used to maintain blood glucose. Liver glycogen Muscle glycogen Sources Glucose other hexoses, Blood glucose only glycerol, glucogenic amino acids, other sources as lacdc acids Fate Blood glucose Lacdc acid Rela:on to blood It is the only source of Never provides blood glucose blood glucose with glucose Func:on General store of glucose Private store of energy for all body cells for muscles only In starva:on It is broken rapidly to Not aﬀected glucose Muscular exercise Not aﬀected Consumes muscle glycogen Cellulose:- Structure:- it’s a polymer of β glucose units linked by β 1-4 glucosidic linkage but it’s non branching. The most abundant CHO found in nature. Source:- cellulose is a consEtute of the wall of plant cells. Proper:es:- 1- in soluble in water. 2- many mammals including humans can’t digest cellulose of diet because of the absence of enzyme that aeacks β – linkage. Importance:- the presence of cellulose in diet is important because it increases the bulk of stool, sdmulates intesdnal movement and prevents consdpadon. 17 Khaled-Elshamy Inulin: - It is a polymer of fructose units. - It’s present in ardchokes. - It’s used as a diagnosdc test for glomerular ﬁltradon rate. - Agar-Agar:- - It’s a polymer of galactose units. - It’s prepared from sea weeds. - It’s used as a culture media for growing of bacteria. - Used for intravenous infusion as plasma subsdtute. Hetero-Polysaccharide:- Gums: - They consist of arabinose and galactose. - They are derived from plants. eg: Gum Arabic Pec:ns: - Formed mainly of α-1-4 linked D-galacturonic acid. They are found in fruit. used in treatment of infandle diarrhea. Mucopolysaccharide (Glycosaminoglycans):- - They are formed from repeadng disaccharide (amino sugar-acidic sugar). - Linked by β-1-3 linkage inside disaccharide and β-1-4 linkage between the successive disaccharide. - The acidic sugar is D-Glucouronic acid or it’s epimer L-idurinic acid. - The amino sugar is D-Glucosamine or D-Galactosamine. - NH2 in amino sugar usually acetylated and amino sugar maybe sulfatedat C4,C6. - The uronic acid and sulfate group cause them to be negadvely charged. - Most of them form the structure component of C.T such as bone, elasdn and collagen. - They act as lubricants and cushion for other Essues because they have the property of holding water. 18 Khaled-Elshamy Glycoproteins Proteoglycans Proteins to which CHO are Protein molecules containing many covalently bound through glycosidic bound GAGS chains. bonds. The length of CHO part is long. The length of CHO part is short. Have serial repeated of CHO. DON’T have serial repeated of CHO. Contain uronic acid and sulfate DON’T Contain uronic acid and group. sulfate group. CHO part is branched. CHO part is branched. Formed of hexoses (N acetyl glucosamine) - pentoses-L-fucosesialic acid (mannosamine-pyrovic acid). Glycosaminoglycans include:- 1- keradn sulphate. 2- chondroidn sulphate. 3- heparan sulphate. 4- Hyaluronic acid. 5- Heparin. 6- Dermatan sulphate. Keratan sulfate: - Disaccharide unit N acetyl glucosamine and galactose. - No uronic acid. - The most heterogenous GAGS because they contain addiEonal monosaccharides such as L-fucose and mannose and N- acetyl neuraminic acid. Keratan sulphate1: found in cornea Keratan sulphatell: found in loose C.T. Chondroi:n 4&6 sulfates: - Disaccharide unit N- acetylgalactosamine and glucouronic acid. - The most abundant GAGS in the body. - Found in cardlage-tendons-ligaments and aorta. 19 Khaled-Elshamy Heparan sulfate: - Disaccharide units same as heparin except some glucosamines are acetylated and there are fewer sulfate groups. - Found in basement membrane and as ubiquitous component of cell surfaces. Hyaluronic acid(Hyaluronate): - Disaccharide unit N acetyl glucosamine and glucuronic acid. - Serves as a lubricant and shock absorber. - Diﬀerent from other GAGS: Un sulfated - noncovalently aeached to protein -Not limited to animal dssue but also found in bacteria. - Found in synovial ﬂuid, vitreous humor of the eye, the umbilical cord loose C.T and cardlage. Heparin: - Disaccharide units Glucosamine and glucuronic or L-iduronic acid. - The most type of GAGS have sulphate group. - α linkage joint the sugar (Another GAGS β linkage). - The only GAGS found intracellular but the other found extracellular. - Found in mast cells that lines arteries specially in liver,-lungs and skin. - Serves as andcoagulant. Dermatan sulfate: - Disaccharide unit N acetyl galactosamine and L- iduronic acid (with variable amounts of glucouronic acid). - Found in skin, blood vessels and heart valves. 20 Khaled Elshamy LIPID 21 Khaled Elshamy LIPIDS Def: They are heterogeneous hydrophobic compounds with long hydrocarbon chain (CH2-CH2-CH2-). - They are insoluble in water and soluble in non-polar solvents as ether and benzene. Biomedical importance of lipid: 1-They form an important consGtuent in diet with high energy value. 2-They contain fat soluble vitamins. 3-They contain essenGal faHy acid. 4-They make diet palatable. 5-They serve as an important storage for energy in the body. 6-they enter in the structure of cell membrane. 7-they act as thermal insulator in the subcutaneous Assue. 8-they support the internal organs as kidney. 9-they act as electrical insulator allowing rapid propagaGon of nerve impulse along the myelinated nerves Fat distribu9on in the body: 1-Assue fat 2-Depot fat ‫اﻟﺪﻫﻮن اﻟﻤﺨﺰﻧﻪ‬ TISSUE FAT: It is a structural fat that enter in the Gssue structure and cell membrane of the cells. - It is constant, not consumed to get energy and not aﬀected by starvaGon. Composed of: cholesterol, phospholipid, glycolipids and small amount of triacylglycerol which mainly contain unsaturated faHy acids. DEPOT FAT: It is stored in adipose Gssue subcutaneously and around the internal organs as kidney. -They are used as a source of energy and consumed during starvaGon. Composed of: mainly Triglycerides which contain long chain saturated and unsaturated FaHy acids and small amount of cholesterol and phospholipid. 22 Khaled Elshamy Sources: 1-from absorbed fat. 2-from CHO by Lipogenesis. Func9on of depot fat: 1-It is an important source of energy 9Kcal/g. 2-support the internal organs as kidney. 3-act as heat insulator to protect the body from cold weather. 4-provide the body with 7-dehydrocholesterol which is converted by vitD3 by exposure of skin to the U.V light. FATTY ACIDS Def: they are monocarboxylic acid that are characterized by their long hydrocarbon chain. Classiﬁca9on of faMy acids A-according to the number of double bond (=):- 1-Saturated faMy acids: have no double bond in their structure. -they are solid at room temperature except if they are short chained (2-4C). Butyric acid (4C): CH3-(CH2)2-COOH (liquid at room temperature) PalmiGc acid (16C): CH3-(CH2)14-COOH. Stearic acid (18C): CH3-(CH2)16-COOH 2-Monounsaturated faMy acid: they have one double bond in their structure. NB: CH3= omega C COOH= Delta C. Omega(ῳ)= No of carbon of F.A – the largest value of delta. Palmitoleic acid (16C): CH3-(CH2)5-CH=CH-(CH2)7-COOH. (Delta 9 OR ῳ7). Oleic acid (18C): CH3-(CH2)7-CH=CH-(CH2)7-COOH. (Delta 9 OR ῳ9). 23 Khaled Elshamy 3-Poly-unsaturated faMy acids: they have more than one double bond in their structure. Linoleic acid (18C): CH3-(CH2)4-CH=CH-CH2-CH=CH-(CH2)7-COOH. (Delta 9-12 and ῳ6) Linolenic acid (18C): CH3-CH2-CH=CH-CH2-CH=CH-CH2-CH=CH-(CH2)7-COOH. (Delta 9-12-15 and ῳ3) Arachidonic acid (20C): CH3-(CH2)4-CH=CH-CH2-CH=CH-CH2-CH=CH-CH2- CH=CH(CH2)3-COOH. (Delta 5-8-11-14 and ῳ6). -Arachidonic acid act as a precursor for prostaglandin.(EXTRA NOTE JUST READING) B-According to the nutri9onal value:- 1-Essen9al faMy acids: they cannot be synthesized by the body so must be taken in diet. EX: poly-unsaturated faHy acids (linoleic – linolenic). 2-Non-essen9al faMy acids: they can be synthesized in the body and don’t have to be taken in our diet. EX: saturated and monounsaturated faHy acids. N.B: Arachidonic acid can be synthesized from linoleic acid so its not considered essenGal F.A but it becomes essenGal when the body lacks linoleic acid (semi essenGal F.A). Importance and proper9es of poly-unsaturated faMy acid (PUFA):- 1-they are present in cis-conﬁguraGon so they are liquid at room temperature. 24 Khaled Elshamy 2-they present more in vegetable oils. 3-they increase the membrane ﬂuidity. 4-they are needed for normal growth. 5-they increase the solubility of cholesterol which prevent the formaGon of stones in the liver. 6-they decrease the incidence of faHy liver. SIMPLE LIPIDS Triacylglycerol: Def: they are esters of 3 faHy acids with trihydroxyl alcohol (glycerol 25 Khaled Elshamy - They are called neutral fat because they are uncharged. - They could be solid (fat) or liquid (oils) according to their content of unsaturated faHy acids. The more unsaturated F.A the more ﬂuidity. Sources: plants: as olives and they usually are oils so they contain essenGal un saturated faHy acids. - Animals: as animal fat and they are fats as buHer. - Marine: as Cod liver and shark liver oils which rich in vit D. TYPES OF TRIACYLGLYCEROL:- -If the 3 faHy acid enter in the structure of TAG are the same this called simple TAG and if the 3 faHy acids are diﬀerent this called mixed TAG. -They are hydrolyzed by pancreaGc lipase to glycerol and free faHy acids. Saponiﬁca9on: TAGs are hydrolyzed by heaGng with alkalies to produce soap (salt of F.A) and free glycerol. Saponiﬁca9on value or number: it represent the number of milligrams of KOH or NAOH required to saponify one gram of fat under speciﬁc condiGoned. - The higher the saponiﬁcaGon value, the lower the faHy acid chain length, the lighter the mean molecular weight of TAGs and vice-versa. 26 Khaled Elshamy Hydrogena9on(Hardening of oils): un saturated F.A can be hydrogenated leading to formaGon of saturated faCy acid in case of complete hydrogenaGon or transunsaturated faHy acids in case of incomplete hydrogenaGon. -such mechanism increase the risk of atherosclerosis. EX: complete hydrogenaGon of palmitoleic acid lead to palmiGc acid formaGon. HalogenaGon: Oils can take halogen (iodine) at the site of double bond and this reacGon is useful to determine the degree of unsaturaGon of oils. Iodine value: is the number of grams iodine taken by 100 grams of fat. -the higher the iodine value, the more unsaturaGon is present in the fat. Rancidity: this is the change in the odour and taste of oils and fats produced by the acGon of bacteria, oxygen and moisture due to occurance of total or incomplete oxidaGon or hydrolysis. -Poly-unsaturated F.A more liable for rancidity than monounsaturated F.A. - products of rancidity are toxic and destroy other factors of food as vit A and essenGal F.A. To avoid rancidity:- 1-Keep the food in cold place to inhibit the acGon of bacterial lipase. 2-Add anGoxidant as vit E (tocopherol) and Vit C (Ascorbic acid). 3-Replace the O2 by inert gas as N2. (this occur in packet of chips) 4-put the food in vacuum (it prevent the oxygen from reacGng with food items). N.B: Properity of ester bond is (saponiﬁcaGon and hydrolysis) but properity of double bond is (hydrogenaGon-halogenaGon-rancidity or oxidaGon). 27 Khaled Elshamy -Waxes:- Def: they are esters of faHy acids with higher monohydroxyl alcohol other than glycerol. -they are important for the making of lubricants, polishes, ointments and cosmeAcs. Ex: Bee wax which contain myricyl alcohol (C30H62O) and called myricyl palmitate. COMPOUND LIPIDS A-Phospholipid:- Def: It is a type of conjugated lipids contain phosphate group. Structure: they are formed of polar heads represented by the phosphate group and non-polar tails of long chain faHy acids. -There are two classes of phospholipids : A-Glycerophospholipids B-sphingophospholipids. 28 Khaled Elshamy A-Glycerophospholipid (phosphoglyceride):- -they are phospholipid that contain glycerol as a backbone. -they are the major class of phospholipid. -phospha9dic acid is the simplest glycerophospholipid and act as a precursor for the other members of this group. -Glycerophospholipid are formed from phosphaGdic acid (PA) and an alcohol :- the phosphate group of phosphaGdic acid is esteriﬁed to another compound contain alcohol group as -PA + serine: phosphaGdylserine -PA + ethanolamine→ phosphaGdylethanolamine (Cephalin). -PA + Choline→ phosphaGdylcholine (Lecithen). -PA + glycerol→ phosphaGdylglycerol. -PA + inositol→ phosphaGdylinositol. -Cardiolipin:- -two molecules of PA esteriﬁed with glycerol so it is called diphosphaGdylglycerol. -it is found in bacteria and eukaryotes. -In eukaryotes it is found in the inner mitochondrial membrane for the the maintainance of the ETC complexes 29 Khaled Elshamy -Plasmalogens:- -when the F.A at C1 of a glycerophospholipid is replaced by un-saturated alkyl group aHached by an ether linkage the plasmalogens is produced. EX: phosphaGdal Ethanolamine (in nerve Assue) and phosphaGdal choline (in heart). -Platelet-ac9va9ng factor (PAF):- -It is an unusual glycerophospholipid in which F.A at C1 replaced by saturated alkyl group aHached by an ether linkage and C2 replaced by acetyl residue. -PAF acGvates the inﬂammatory cells and mediates hypersensiGvity, acute inﬂammatory and anaphylacGc reacGons. -Sphingophospholipid -they are phospholipid that have the amino alcohol sphingosine as a backbone rather than glycerol. -when the amino group of sphingosine aHached to long chain F.A it produce ceramide. -when the OH group at C1 in ceramide esteriﬁed with choline it produce sphingomyeline. 30 Khaled Elshamy Func9on of phospholipids:- 1-It enter in the structure of cell membrane. 2-Brain and nerves are rich in sphingomyelin and cephalin. 3-It enter in the structure of lipoproteins that are important in lipid transport. 4-It enter in the structure of lung surfactant (lecithin). B-Glycolipid ( Later at CNS module) C-Lipoproteins:- Def: they are formed of lipid which is conjugated with Protein (apolipoprotein). Examples: 1- chylomicron (CM). 2-Very low density lipoprotein (VLDL or pre β lipoprotein). 3-low density lipoprotein (LDL or β lipoprotein). 4-High density lipoprotein (HDL or α lipoprotein). Distribu9on: 1-cell membrane 2-plasma. Structure: they are formed of hydrophobic core (cholesterol ester and TAGs) and hydrophilic coat (Apoprotein and free cholesterol and polar part of phospholipid). Func9on: they convert water in soluble lipids into water soluble complexes which facilitate transport of lipid between blood and diﬀerent Assues. 31 Khaled Elshamy LIPOPROTEIN FUNCTION chylomicron Transport exogenous (dietary) TAGs and cholesterol from intesGne to peripheral Gssue VLDL Transport of endogenous (Synthesized) TAGs from liver to peripheral Gssue LDL Transport of cholesterol to Gssues HDL Reverse cholestrol transport. Removes the accumulated cholesterol from peripheral Gssue to liver. Lipoproteins and atherosclerosis:- -LDL represents the transport of cholesterol to the Gssues while HDL represents the removal of cholesterol from the Gssues. -increased level of LDL (Bad cholesterol) is associated with atherosclerosis and coronary heart disease. -increased level of HDL (Good cholesterol) in blood represents the protecGon from atherosclerosis and coronary heart disease 32 Khaled Elshamy DERIVED LIPID Def: They are substances derived from the simple and conjugated lipids by hydrolysis. EX:1-FaHy acids 2-Glycerol 3-steroids and sterols 4-fat soluble vitamins (A-D-K-E). Sterols and steroids Def: they are compounds that contain steroid nucleus which is called cyclopentanoperhydrophenanthrene in their structure. EX: Cholesterol. Cholesterol:- Distribu9on: 1-in every body cell (cell membrane) especially in adrenal cortex, liver, kidney and brain. 2-in blood in two forms free cholesterol and cholesterol ester (combined with F.A). -the normal level of cholesterol in blood is 220mg/dl. Any increase above that level is known as hypercholesterolemia. -It is insoluble in water and soluble in fat solvents. -it is present only in animal and not in plants. Func9on of cholesterol:- 1-It enter in the structure of cell membrane. 2-it is used for synthesis of steroid hormones. 3-it is used for synthesis of bile salts. 4-synthesis of vit D3. Cholesterol deriva9ves: 1-Vit D3 2-Bile salts 3-Steroid hormones. 33 Khaled Elshamy 1-Vitamin D3: It is derived from 7-dehydrocholesterol by U.V light. 2-Bile salts: they are formed from oxidaGon of cholesterol in liver and later reabsorbed from intesGne and secreted in bile. Func9on of bile salts: 1-EmulciﬁcaGon of lipid during digesGon. 2-AcGvaGon of pancreaGc lipase. 3-help absorpGon of fat soluble vitamins. 4-solubilizing cholesterol in bile and prevent gall stone formaGon. 5-have cholereGc acGon (sGmulate their own secreGon from liver). 6-intesAnal anAsepGc that prevent putrefacGon. 3-steroid hormones: they include A-female sex hormones (estrogen and progesterone). B-male sex hormones (testosterone). C-Suprarenal corGcal hormones mineralocorGcoids and glucocorGcoids as (aldosterone and corGsol) 34 Khaled-Elshamy PROTEIN 35 Khaled-Elshamy Protein Chemistry - They are organic compounds of high molecular weight consisdng of α amino acids that are linked together by a pepdde bond. - -Nitrogen forms 16% of protein molecules. Biomedical importance of proteins 1. almost all enzymes are protein in nature. 2. Transport of small molecules EX:HB carriesO2. 3. Structural elements: Protein enters in the structure of the cell membrane in the form of glycoproteins. 4. Some hormones are protein in nature, such as growth hormone and its receptors. 5. Defense mechanisms: Andbodies are protein in nature and keradn is found in the skin to protect it. 6. Clovng factors are protein in nature. 7. Storage for example, ferridn that is used for iron storage. 8. Transcripdon factors that play an important role in the reguladon of gene transcripdon. Amino Acids - They are the building blocks of the polypepdde chains of proteins. - Each amino acids contain both a primary amino group and a carboxylic group except [Proline] has a secondary amino group. - The amino acids enter in the structure of protein are L-α amino acids. - L-amino acid: the amino group aeached to α carbon on the lew side. - D-amino acid: the amino group aeached to alpha carbon on the right side. - At Physiological PH (7.4) COOH group is dissociated forming negadve charge [Coo-] and NH2 group Protonated forming Posidve charge [NH3+]. 36 Khaled-Elshamy - - AT Physiological PH, All amino acid contain posidve and negadve charge. 37 Khaled-Elshamy Classiﬁca9on of amino acids:- According to their structure:- 1. Alipha:c: with no ring structure. eg: alanine. 2. Aroma:c: contains benzene ring. eg: Phenyl alanine. 3. Heterocyclic: contain ring structure other than benzene ring. eg: Tryptophan (Pyrrole ring) - His9dine (Imidazole ring) - Proline [Pyrrole ring]. According to their polarity:- Hydrophobic Hydrophilic -In the interior of The Molecule. Have -on the surface of Molecule. non Polar side chain. -Have Polar side chain. -Don't gain or loss Proton. -Their side chain contain of N or O atoms. -Don't Pardcipate in H bond or ionic bond. -Some of them are charged at Physiological PH. -oily like or lipid like. -Have hydro Phobic interacdon. According to their content of COOH and NH2 groups:- 1. Neutral: Monocarboxylic and Monoaminogroup. eg: glycine 2. Acidic: They contain more than one COOH group. eg: aspartate-glutamate. 3. Basic: such amino acids contain more than one amino group eg: ArgininelysineHis9dine Nutri:onal Classiﬁca:on:- 1. Essen:al amino acids: They are amino acids that could not be synthesized by the body. 2. Non essen:al amino acid: They are amino acids that can be synthesized by the body. 3. Semi-essen:al amino acid: eg: Arginine – hisddine. Examples of non-essen:al A.A:- G scap+Tyrosine except arginine&phenylalanine. Any other amino acid is essendal. * Non essendal amino acid may be synthesized in the body from essendal amino acid. Metabolic classiﬁca:on:- According to their metabolic fate into: 38 Khaled-Elshamy 1. Pure glucogenic: Their Metabolic fate is Glucose. 2. Pure ketogenic: Their metabolic fate is keton bodies. eg: Leucine and Lysine. 3. Glucogenic and ketogenic (Mixed): eg: Phenylalanine–tyrosine-tryptophan and isoleucine. Important notes:- - Serine and threonine are sites for o-linked glycosyladon of Proteins. - Asparagine is site for N-linked glycosyladon of Proteins. Cysteine:- sulfer containing. - Can form disulﬁed bond. -Terdary structure of Protein (stabilized by it). -Destroing disulﬁed bond denaturate protein. Methionine:- sulfer containing, Part of s-adenosylmethionine [SAM]. - A methyI donor in biochemical Pathways. Proline:- ﬁve membered ring structure. - secondary Amino group (imino acid). - Contribute To formadon of ﬁbrous Collagen. Cys:ne:- its 2 molecules of cysteine united together by removal of hydrogen of S-H groups. Basic Amino acids (posi:vely Arginine- Lysine – Hisddine. charged) Acidic Amino acids (nega:vily Asparatate- Glutamate. charged) Hydroxy containing Aminoacids Serine- threonine- Tyrosine. Sulfur Containing Aminoacids Cysdne- Cysteine- methionine. Branched Amino acids: Valine- Leucine- Isoleucine. Aroma:c Amino acid Phenylalanine-tyrosine-tryptophan. 39 Khaled-Elshamy Hetero cyclic Amino acids: Tryptophan- Hisddine- proline. Non essen:al Amino acids: G Scap + Tyrosine except Arginine and Phenylalanine. Essen:al aminoacids: Any amino acid rather than above is essendal. Hydrophilic amino acids (polar): Basic- acidic-sulfer-hydroxy amino acid + glutamine and asparagine. Hydrophobic amino acids (non polar) any amino acid another them (above). Ketogenic amino acid lysine and leucine. Glucogenic and ketogenic (mixed) tryptophan- tyrosine- phenylalanine and isoleucine. Glucogenic amino acids The rest of amino acids Proper9es of amino acids:- - The alpha carbon of amino acids is asymmetric carbon because it is aeached to four diﬀerent groups. - Amino acids that have asymmetric alpha carbon can exist in D and L forms. - All amino acids enter in protein structure are opdcally acdve except Glycine opdcally inacdve because it does not have asymmetric alpha carbon. - All amino acids enter in protein structure are in the L – Conﬁguradon. - D-Amino acids are found in some andbiodcs and cell wall of bacteria. Amphoteric character: due to the presence of both NH2 and COOH groups so amino acids can act as proton donor or acceptor according to PH. Iso electric point (I.E.P): it’s deﬁned as the PH value at which amino acid carries both posidve and negadve charge at the same dme. So at I.E.P amino acids can’t migrate neither to the cathode nor anode and can be precipitated at this point. 40 Khaled-Elshamy Above I.E.P (High PH): amino acids carry negadve charge as COOH group donate it’s proton. Below I.E.P (low PH): amino acids carry posidve charge as NH2 group act as proton acceptor. Forma9on of pep9de linkage:- - It’s formed by condensadon of COOH and NH2 groups of two amino acids with removal of H2O molecule. - It’s catalysed by pepddyl transferase enzyme. -Pepdde bond aren’t broken by condidons that denaturate protein. - Has a pardal double bond character. Levels of protein structure Primary structure:- -It is deﬁned by the number, type, and sequence of amino acids in the polypepdde chain. -The amino acid sequence must be wrieen from the N-terminus to the C-terminus. -The amino acid sequence is speciﬁc for each protein -Each polypepdde chain has free terminal amino group (N-terminus) of the ﬁrst amino acid and a free terminal carboxyl group (C-terminus) belongs to the last amino acid of the polypepdde chain. -Synthesis of polypepdde chain starts from N-terminus towards C–terminus. - Changing one amino acid leads to changes in the funcdon of proteins which lead to Some diseases e.g. sickle-cell anemia result from a change in a single amino acid in the polypepdde chain (glutamate valine in posidon no. 6) 41 Khaled-Elshamy Secondary structure:- - Its The Coiling of the Polypepdde chain. - Its stabilized by hydrogen bonds. α-helix β-Pleated sheet -The most common helices found in -It's fully extended structure (Zigzag). nature. -Composed of two or more Poly -It is a spiral Structure. PepGde chains or segments of Poly PepGde chain. -The side chain of Amino Acids extending outward From The central -Parallel: If the pepGde chains are axis to avoid interfering sterically with running in the Same direcGon. each other. -AnG Parallel: if the PepGde chains are -Composed of only one Poly PepGde running in the opposite direcGons. chain -found in Fibrous protein such as -H Pond formed between the carbonyl keraGn of stretched hair. oxygen (C = o) and amide hydrogen (NH) of the next forth amino acid (1_4). -Each Turn Contain 3.6 amino acid. -Disrupted by proline. -found in globular Proteins + globin and ﬁbrous Protein as keraGn. -Right handed [Common] and le~ handed. -Taking diﬀerent forms as: α-helix or β-Pleated Sheet. 42 Khaled-Elshamy Ter:ary structure:- - This is the ﬁnal arrangement of a single polypepdde chain resuldng from spadal reladonship of more distant amino acid residues. There are two forms of ter:ary structures: a) Fibrous: which is an extended form e.g. keradn, collagen and elasdn b)Globular: which is a compact form and results from folding of polypepdde chain e.g. myoglobin. Bonds responsible for ter:ary structure are: a) Hydrogen bonds: within the chain or between chains b) Hydrophobic interacdons: between the non polar side chains (R) of neutral amino acids c)Ionic bonds: between oppositely charged groups in the side chains of amino acids e.g. amino group of lysine and carboxyl group of Aspartate. d)Disulﬁde bonds: between cysdene residues within the chain. Quaternary structure:- -Many proteins are composed of several polypepdde chains. Each poly pepdde chain is called: subunit. Each subunit has its own primary, secondary and terdary structure. -May be essendal for the acdvity of certain proteins e.g. enzymes and haemoglobin. - Stabilized by hydrogen bond, electrostadc interacdons, hydrophobic interacdons, Van der Waals interacdons, and disulﬁde bonds. - The bond between subunits are non covalent bonds. -The bond between individual subunits may be covalent bonds such as disulphid bond. Chaperones: They are group of molecular proteins that promote eﬃcient protein folding and prevent aggregadon. 43 Khaled-Elshamy -Age- related defect in acdon of chaperons may lead to some diseases as Alzheimerand Parkinson's disease. Protein denatura)on - It is due to the rupture of chemical bonds that stabilize the secondary, terdary, and quaternary structure of the protein.(primary no) - It may be reversible or irreversible and may result in protein coaguladon - e.g: albumin coaguladon by heat (due to formadon of disulﬁde cross linkage). Factors that produce denatura:on: Physical agents as heat, mechanical agita9on, sonica9on, ultraviolet irradiadon X-ray..etc Chemical agents as acids, alkalis, alcohols, urea, salts of heavy metals like Pb2-Ag2- Cu2.. etc. Eﬀects of denatura:on on proteins: *Loss of the secondary, terdary, and quaternary structure of proteins. (primary no so pepdde bond doesn’t break). *Increased viscosity. *Decreased solubility due to exposure of nonpolar hydrophobic groups. *Increased digesdbility by proteolydc enzymes due to exposure of pepdde bonds. *Loss of biological acdvity e.g inacdvadon of enzymes. *Loss of andgenic property i.e injecdon of denatured protein cannot induce andbody formadon within the body. Classiﬁca)on of protein A) Simple Proteins:- * They are proteins that give only amino acids on hydrolysis i.e. they are formed of proteinpart only. * Albumins and globulins: Both proteins are of high biological value. it contains all essendal amino acids. Albumins and globulins are almost present in the same sources as blood, milk and eggs and are coagulated by heat. * Gliadins and glutenins: Both are acidic proteins and mainly present in cereals. They are soluble in alkalis. 44 Khaled-Elshamy * Scleroproteins: They are ﬁbrous proteins of suppordve and protecdve funcdons. They are insoluble in water, saline, dilute acids, or alkalis. They are neither digested nor used for amino acids consumpdon. They include collagen, elasdn, and keradn. B) Conjugated Proteins:- * They are formed of protein (apoprotein) and non-protein part (prosthedc group) * Phosphoproteins: These proteins are formed of proteins conjugated with phosphate group e.g casein which is the milk protein. * Lipoproteins: These proteins are formed of protein conjugated with lipids. They are used for lipid transfer in blood. * Nucleoproteins: These proteins are conjugated with nucleic acid (DNA) to form chromosomes. * Metalloproteins: These proteins are conjugated with metals such as haemoglobin and ferridn.(iron Fe), Ceruloplasmin (copper Cu) and insulin (zinc Zn) *chromoproteins: is a conjugated protein that contains a pigmented prosthedc group (or cofactor). -A common example is haemoglobin. Derived Protein:- Primary:- They are denaturated protein. Secondary:- They are hydrolydc products of protein eg: peptones and amino acids. 45 Khaled Elshamy ENZYMES 46 Khaled Elshamy ENZYMES DEF:- They are speciﬁc protein catalyst that accelerate the rate of chemical reacGon. Substrate:- is the reactant that enter the chemical reacGon on which the enzyme work. The rate of chemical reac9on:- The change in the amount of substrates or products per a unit of Gme General properi)es of enzymes:- 1-they are protein (globular) in nature except ribozymes are RNA in nature as rRNA. 2-catalyzed reacGon is faster than uncatalyzed reacGon from 1000:100000000 Gmes. 3-Enzymes not consumed or change in structure during the reacGon. 4-they don’t aﬀect the equilibrium of the reacGon. 5-they act within a moderate temperature and PH range 6-they may be produced and located intracellular as metabolic enzymes or produced inside the cell and excreted later outside the cell as digesGve enzymes. 7-they are highly speciﬁc and they are diﬀerent forms of speciﬁcity as: A-Op9cal or stereo speciﬁcity: as maltase enzyme act on α-glycosides and not work on β-glycosides. D-amino acid oxidase work only on D-amino acids and L-amino acid oxidase work only on L-amino acid oxidase. B-Group speciﬁcity: enzymes act on a speciﬁc group or bond as pepsin work on the pepGde bond in which the amino group is contributed by an aromaGc amino acid. 47 Khaled Elshamy C-Absolute speciﬁcity: enzyme works only on one substrste as urease enzyme on urea. Structure of enzymes Simple enzyme:- enzyme are formed of protein only. Conjugated enzyme (Holoenzyme):- enzyme are formed of protein part and nonprotein part. if the non protein part is inorganic as metal Zn , Mg its called cofactor. If the non protein part is organic called coenzyme. If the coenzyme is loosely aHached to the enzyme called cosubstrate as NAD and if it Gghly aHached it is called protheGc group as FAD. Complex enzyme:- they are formed of several subunit and each subunit has a diﬀerent catalyGc acGvity. EX: faHy acid synthase enzyme. Classiﬁc)on of enzymes We have six classes of enzymes according to reacGon they catalyze. 1-OXIDOREDUCTASES -this group of enzymes catalyzes the reacGons of oxidaGon and reducGon EX: oxygenases , dehydrogenases ( use NAD and FAD as a coenzyme) , oxidases and reductases. 48 Khaled Elshamy 2-TRANSFERASES -this group of enzymes catalyze the transfer of groups other than hydrogen from one substrate to another. - they are further classiﬁed according to the group they transfer as phosphotransferase(kinases) or transphosphatase , methyltransferase or transmethylase. - synthases belong to transferases but synthetases belong to ligases as they use ATP. N.B: DNA polymerase , RNA polymerase and reverse transcriptase are transferases. 3-HYDROLASES -this group of enzymes catalyze hydrolysis by addiGon of water. EX: PepGde bond by pepGdase , glycosidic bond by maltase , ester bond by lipase and urea by urease enzyme. 49 Khaled Elshamy 4-LYASES -this group of enzymes catalyze the cleavage of C-C, C-N, C-O and C-S bonds. It is alse involved in removal or addiGon of CO2, H2O and ammonia across double bonds. NB: there is no ATP is used and addiGon of H2O not compined with breakdown of the substrate. EX: pyruvate decarboxylase. 5-ISOMERASES -this group of enzymes catalyze the interconversion between two isomers (no change in the molecular weight). EX:-isomerase, mutase, epimerase and racemase. N.B: intramolecular group transfer belong to isomerases not transferases. 50 Khaled Elshamy 6-LIGASES -this group of enzymes catalyze formaGon of bonds between C-O, C-S and C-N and joining of two substrates using high energy phosphate compounds as ATP. EX: pyruvate carboxylase. NB: synthetase enzymes belong to ligases as they use ATP. 51 Khaled Elshamy Enzyme nomenclature Trival naming: by addiGon of suﬃx-ase to the name of the substrate as urea→urease and there is some names not related to the substrate as pepsin and trypsin. Systemic naming or EC number: it contain four digits indicaGng the class of enzyme, the funcGonal group upon which the enzyme work, the name of coenzyme and the substrate on which the enzyme work as 1.1.1.27 which means :- 1. Oxidoreductases 1.1.acGng on CH-OH group of donors 1.1.1. NAD or NADP is coenzyme 1.1.1.27 L-lactate dehydrogenase Characters of ac9ve site of the enzyme:- -It is the site for substrate recogniGon. -at this site substrates are brought into close proximity to each other. -catalysis is enhanced by the capacity of acGve site to shield substrate from water and generate good environment for chemical reacGon. -it is usually located at the surface of the molecule as a clef or pocket and it represents a small part of the total volume of enzyme. -during the chemical reacGon, enzyme interact with substrate temporarily forming ES complex and then it is followed by dissociaGon of this complex into enzyme and product. They are two theories that explain haw substrate bind to the ac9ve site of enzyme: 1-lock and key theory: the acGve site is complementary to the conformaGon of the substrate and according to this theory, enzyme is highly speciﬁc to one substrate (Absolute speciﬁcity). 2-Induced ﬁt theory: the enzyme change its shape upon binding with the substrate. So, enzyme can act on more than one substrate (group speciﬁcity). 52 Khaled Elshamy Mechanism of ac)on of enzymes -virtually, all chemical reacGons have an energy barrier separaGng the reactants and the product and this barrier is called free energy of acGvaGon. -Free energy of acGvaGon: the energy diﬀerence between that of the reactants and the transiGon state that occurs during the formaGon of product. -for molecules to react they must contain suﬃcient energy to overcome the energy barrier of the transiGon state. -in the absence of enzyme, only small porGon of substrate may posses enough energy to achieve transiGon state. -in the presence of acGvaGon, enzyme accelerate the rate of chemical reacGon by decreasing free energy of acGvaGon needed by substrate to reach to the transiGon state. -enzyme not aﬀect the free energy of substrate or product. 53 Khaled Elshamy Mechanisms of catalysis 1-catalysis by proximity:when substrate bind to the acGve site of the enzyme it creates a region of high local substrate concentraGon and also this environment orients the substrate molecule spaGally in a posiGon ideal for them to react resulGng in rate enhancement at least 1000 folds. 2-Acid-Base catalysis: such mechanisms of catalysis depends on donaGon or accepGon of protons by COOH and NH2 present in the acGve site of the enzyme. 3-Covalent catalysis: it involves formaGon of a covalent bond between the enzyme and substrates introducing a new reacGon pathway. Then, enzyme returned back to its original form at the end of the reacGon. 54 Khaled Elshamy 4-Strain catalysis: such mechanism is common with hydrolases and lysozymes. These enzymes stretch or distorts the target bond, weaking it and make it more vulnerable to cleavage. Factors aﬀec9ng the enzyme ac9vity: 1-Enzyme concentraGon. 2-Substrate concentraGon 3-PH 4-Temperature 5-presence of acGvator 6-presence of inhibitor 1-Enzyme concentraGon: -the rate of the reacGon is directly proporGonal with enzyme conc when substrate have constant conc. EX: if the enzyme conc is halved, the iniGal rate of the reacGon Vo as well as Vmax are reduced to half that of the original. 55 Khaled Elshamy 2-Substrate concentraGon: -the rate of the reacGon increased with substrate conc unGl a maximum velocity Vmax is reached. Vmax: at which the enzyme is fully (100%) saturated with substrate. The michaleis-menten equa9on describes how the reacGon velocity varies with substrate concentraGon. most enzymes show michaleis and menten kineGcs show hyperbolic shape of the enzyme kineGc curve. KM: is the amount of the substrate needed to reach half of the Vmax (50% of enzyme saturated with substrate). KM and aﬃnity of the enzyme for its substrate is inversely proporGonal to each other. Lineweaver-burk plot: when Vo is ploHed against substrate conc, its not always possible to determine when Vmax has been achieved. However, 1/Vo is ploHed against 1/S conc a straight line obtained and it can be used to calculate KM and Vmax. 3-Temperature: -the reacGon velocity increases with temperature unGl Vmax is reached. -the op3Gmum temperatue for most human enzymes from 35 to 40C and this enzymes above 40C denaturate. 56 Khaled Elshamy 4-PH: -the PH at which the maximal enzyme acGvity is achieved is diﬀerent for diﬀerent enzymes as pepsin works at PH=2 and alkaline phosphatase works at PH=8:10. -the extremes of PH lead to denaturaGon of enzymes. 5-Presence of acGvator: -some enzymes called zymogens are produced in inacGve form. Zymogens are acGvated later by removal of its polypepGde chain that masks the acGve site in the presence of acGvator. EX:pepsinogen converts to pepsin in the presence of HCL. 57 Khaled Elshamy 6-Enzyme inhibitors A-Compe99ve inhibitor: -there is structural similarity between the inhibitor and substrate. -the inhibitor competes the substrate for binding to acGve site. -inhibiGon is reversible and can be overcomed by increase substrate concentraGon. -KM increases but Vmax is constant. EX: malonate with succinate dehydrogenase and methotrexate with sulfanilamide. B-Non compe99ve inhibitor: -there is no structural similarity between substrate and inhibitor. -the inhibitor binds to site other than acGve site of the enzyme leading to destabilizaGon of the transiGon state and formaGon of inacGve E/I and E/I/S. -inhibiGon can be reversible or irreversible (enzyme poison). -KM is constant and Vmax decrease. 58 Khaled Elshamy C-Un compe99ve inhibitor: -inhibitor binds to the E/S complex. -the lineweaver-burk plot for uncompeGGve inhibitor produces a line parallel to the original enzyme substrate plot. -KM and Vmax is decreased. -some drugs works as inhibitor as penicillin and amoxicillin that inhibiGng the enzymes involved in bacterial cell wall synthesis and Captopril and lisinopril which works as ACEs inhibitors to decrease Bp. Regula9on of enzyme ac9vity: A-short term regula9on: 1-Allosteric regulaGon 2-covalent modiﬁcaGon (phosphorylaGon and dephosphorylaGon B-Long term regula9on: repression or inducGon of enzyme gene3c biosynthesis. Allosteric enzymes: -they are enzymes that have allosteric site rather than the acGve site of the enzyme. -the molecule that bind to the allosteric site called eﬀector which may be posiGve if it increase the enzyme acGvity or negaGve if it decrease it. -the presence of the allosteric eﬀector can alter the enzyme aﬃnity for its substrate or modify the maximal catalyGc acGvity for the enzyme or both. 59 Khaled Elshamy Types of eﬀector: A-Homotropic eﬀector: when the substrste it self serves as as eﬀector. B-Homotrobic eﬀecror: diﬀerent form other than substrate work as eﬀector as the ﬁnal product. -when the ﬁnal product work as an eﬀector for the enzyme that synthesisze it its called negaGve feedback inhibiGon. Eﬀect of substrate binding on allosteric enzymes: -the presence of a substrate molecule at one site on the enzyme enhances the catalyGc properiGes for other sites which is called cooperaGvity. NB:Allosteric enzymes don’t undergo michaelis-menten kineGcs due to the concept of cooperaGvity and show sigmoid S shaped curve rather than hyperbolic curve. 60 Khaled Elshamy Enzymes of clinical importance: 61 Khaled Elshamy -importance of non funcGonal plasma enzymes that they help in diagnosis and follow up of organ diseases as 1-in MI → increase level of CKMB and LDH. 2-Cancer prostate → increase level of acid phosphatase 3-Cholestasis and increase the osteoplasGc acGvity → increase level of alkaline phosphatase. ISOENZYMES DEF: they are diﬀerent forms of the same enzyme that catalys the same reacGon. -they are physically and chemically diﬀerent from each other. -diﬀer en enzyme kineGcs (KM , Vmax ). -they have diﬀerent A.A sequence. LACTATE DEHYDROGENASE: -It presents in almost all Gssues. -it is formed from 4 polypepGde chain and have 5 diﬀerent isoenzymes as follow: Isoenzyme Structure Present in LDH1 HHHH Heart and RBCs LDH2 HHHM Heart and WBCs LDH3 HHMM Lung, Brain and Kidney LDH4 HMMM Kidney, placenta and pancrease LDH5 MMMM Skeletal muscles and liver Clinical signiﬁcance: in acute MI LDH rises within 12 to 24 hours, aHains a peak at 48 hours (2:4 days) and then return to normal from 8 to 14 days. 62 Khaled Elshamy Crea,ne kinase: -composed of 2 polypep3de chain. -have 3 isoenzymes CK-MM (SK.MS) , CK-MB (Heart) and CK-BB (Brain). Clinical signiﬁcance: used for MI diagnosis. Following acute MI CK-MB increase in the blood within 4 to 8 hours following chest pain onset , reach its peak at approximately 24 hours and return to baseline aMer 48:72 hours. 63 Khaled Elshamy QUESTIONS 64 Khaled Elshamy MONOSACCHARIDES 65 Khaled Elshamy 1- The general formula of monosaccharide is? A-CnH2nOn B-(CH2O)n C-Cn(H2O)n-1 D-A and B 2- Which of the following is not consider a monosaccharide? A-C2H4O2 B-C3H6O3 C-C4H8O4 D-C5H10O5 3- Classification of monosaccharide according to all of the following except A-number of carbon B-the functional group C-number of sugar units D-All of the above true 4- Which of the following is false about monosaccharide? A-the simplest form of CHO B-The smallest sugar is formed of 3 Carbon C-Can be hydrolysed D-None of the above 5- Which of the following is Aldotriose? A-fructose. B-glycerose C-ribose D-dihydroxyacetone 6- Which of the following is ketopentose? A-glyceraldehyde. B-ribulose. C-erythroulose. D-fructose 7- Each gram of CHO gives...... Kcal? A-3 B-4 C-9 D-12 8- The most abundant organic molecule found in nature is? A-CHO B-protein. C-Fat D-water 66 Khaled Elshamy 9- Which of the following sugars enter in the structure of RNA and High energy phosphate compounds as ATP? A-Deoxyribose B-Ribose C-Arabinose D-lyxose 10- Which of the following sugars found in human heart muscles? A-lyxose B-Ribose. C-Arabinnose. D-Xyloulose 11- Which of the following sugars found as intermediate in uronic acid pathway? A-Arabinose B-Xyloulose C-ribose D-lyxose 12- Which of the following is considered the sugar of fetal blood? A-Glucose B-mannose. C-galactose. D-fructose 13- Spermatozoa in the seminal fluid use which sugar as a source of energy? A-glucose. B-fructose C-mannose. D-galactose 14- Which of the following sugars is the main metabolic fuel in our body? A-glucose. B-fructose C-galactose D-mannose 15- Compounds have the same chemical formula but differ in the spatial configuration? A-stereoisomers. B-optical isomers C-Anomers. D-Epimers 16- Number of asymmetric carbons in fructose is? A-2. B-3. C-4. D-5 67 Khaled Elshamy 17- Number of asymmetric carbons in Alpha-D-glucose? A-3 B-4 C-5. D-6 18- Number of isomers of glucose? A-10. B-12 C-14 D-16 19- Which of the following the reference sugar? A-Deoxyribose B-fructose. C-glucose D-glycraldehyde 20- A special type of isomers found in the pairs of structure that are mirror image of each other? A-enantiomers B-epimers C-aldose ketose isomers D-anomers 21- Which of the following enzyme can convert the sugar from D from to L form? A-epimerase B-Aldolase C-Racemase D-sucrase 22- Type of stereoisomers that found between D-glucose and L-glucose? A-enantiomers B-epimers. C-anomers D-aldose ketose isomer 23- The position of H and OH is differ at all carbon in enantiomers? A-true B-false 24- Isomers differing as a result of variations in configuration of H and OH on carbon atoms 2 ' 3 and 4 of glucose are known as? A-Epimers. B-Anomers. C -optical isomers. D-enantiomers 68 Khaled Elshamy 25- Two sugars which differ from each other only in configuration around one carbon atom is? A-enantiomers. B-epimers. C-anomers. D-aldose ketose isomers 26- Which of the following is false about epimers? A-glucose and mannose epimers at C2 B-glucose and galactose epimsrs at C4 C-number of epimeric carbon in glucose is 3 D-Mannose and galactose are epimers 27- In glucose the orientation of H and OH groups around the carbon atom 5 adjacent to the terminal primary alcoholic group determines? A-D and L series B-Dextro and levorotatory C-alpha and beta anomers D-epimers 28- Which of the following is true about anomers? A-isomers obtained from the change of H and OH at the anomeric carbon. B-Found only in ring structure C-Alpha-D glucose and beta-D glucose are examples D-All of the above is true 29- At which carbon atom the OH become below after cyclization of glucose to alpha-D-glucose? A-C2'C3'C4 B-C1'C3'C5 C-C1'C2'C4 D-C1'C2'C5 69 Khaled Elshamy 30- Which of the following is optically inactive sugar? A-glycerose B-Dihydroxyacetone C-ribose 31- If you dissolve pure crystals of glucose in water and leave the solution for equilibrium, the solution will contain? A-only Alpha-D-glucose B-only open chain of glucose C-only alpha and beta-D glucose D-open chain and alpha and beta-D glucose. 32- The predominant form of glucose in the solution is? A-Acyclic form B-Hydrated cyclic form C-glucofyranose. D-glucopyranose 33- Mutarotation refers to change in? A-PH B-optical activity C-conductance. D-chemical properties 34- Alpha D glucose +112 converted to +52,5 and Beta D glucose +19 converted to +52,5 represents? A-optical isomerism B-Epimerisation C-mutarotation D-D and L isomers The carbon atom 35- which becomes asymmetric after cyclization is known as? A-anomeric carbon B-epimeric carbon C-isomeric carbon 36-Number of asymmetric carbon in dextrose? A-3 B-4 C-5 D-6 70 Khaled Elshamy 37- Mutarotation is due to interchange between? A-D and L form of sugar B-alpha and beta form of sugar 38- Glyceraldehyde-3-phosphate is an example of......reaction? A-fermintation B-esterification C-oxidation. D-reduction 39- Oxidation of the last primary alcoholic group gives? A-uronic acid B-aldonic acid C-aldaric acid D-None of the above 40- Galactose oxidation in the presence of conc HNO3 gives? A-galactouronic acid B-galactonic acid C-mucic acid D-saccharic acid 41- Oxidation of glucose in the presence of dil HNO3 gives? A-glucouronic acid B-gluconic acid C-glucaric acid D-mucic 42- Which of the following is false about glycosidic linkage? A-formed by condensation of OH group of anomeric carbon with the OH of another molecule B-All sugar-sugar linkage from O type C-All sugar-protein linkage from N type D-All of the following are true 71 Khaled Elshamy 43- Which of the following is sugar alcohol? A-sorbitol B-lyxose C-trehalose D-glucouronic acid 44- Reduction of which of the following can give sorbitol? A-glucose B-fructose C-mannose D-A and B 45- Reduction of which of the following can give mannitol? A-mannose B-fructose C-glyceraldehyde D-A and B 46- Which of the following is reducing? A-Glucouronic acid B-Glucaric acid C-Gluconic acid D-All of the above 47- Which of the following considered amino sugar? A-Mannitol B-glucosamine C-glucouronic acid D-glucose 48- Which of the following compounds has CH3 in their structure? A-galactosamine B-deoxyribose C-L-fucose D-mannitol 72 Khaled Elshamy DISACCHARIDES 73 Khaled Elshamy 1- The general formula of disaccharide is? A-CnH2nOn B-Cn(H2O)n-1 C-CnH2nO2n D-(C6H10O5)n 2- Which of the following is true about sucrose sugar? A-called the table sugar B-formed from alpha-D-Glu and beta-D-Fru C-the glycosidic linkage in it alpha1-2glucosidic linkage D-All of the above 3- Which of the following is true about invert sugar? A-its dextrorotatory sugar. B-its non reducing sugar C-found naturally in bee honey D-None of the above 4- Which of the following is true about sucrose? A-can form ozazone crystals B-it’s a levorotatory sugar C-Can show Mutarotation D-All answers are false 5- Which of the following is true about lactose sugar? A-formed from Alpha-D-glucose and beta-D galactose B-it is reducing sugar C-best sugar for babies D-All of the above 6- Lactose intolerance is a type of milk allergy? A-true B-false 7- Which of the following is true about maltose sugar? A-formed from two Alpha-D-glucose B-contain free aldehyde group C-Can be hydrolyzed by maltase enzgme D-all of the above 74 Khaled Elshamy 8- Which of the following sugars contain Alpha 1-1 glucose linkage? A-sucrose B-trehalose C-lactose D-maltose 9- Which of the following disaccharides formed from two Beta glucose? A-maltose B-trehalose C-sucrose D-celliobiose 10- Which of the following disaccharides is non reducing? A-sucrose B-mannose C-trehalose. D-A and C 75 Khaled Elshamy POLYSACCHARIDES 76 Khaled Elshamy 1-which of the following not considered homopolysaccharide? A-starch B-inulin C-Agar D-Gums 2-the general formula of polysaccharide is? A-(C6H10O5)n B-(C6H12O5)n C-C6H10O6)n D-(C5H10O5)n 3-starch is? A-reducing sugar B-give blue color with iodine C-hydrolysed by amylase to glucose subunits D-contain α-1-4 glucosidic bonds only. 4-starch is? A-homopolysaccharid of plant origin B-contain α-1-4 and α-1-6 glucosidic linkage C-formed of amylose and amylopectins. D-all of the above 5-which of the following is true about the outer layer of starch granule? A-non branching layer B-constitutes 15:20 % of the granule C-resembles glycogen in structure D-give blue color with iodine 77 Khaled Elshamy 6-hydrolysis of starch by pancreatic amylase produces? A-reducing disaccharide. B-reducing monosaccharide C-non-reducing disaccharide D-none of the above 7-which of the following produced by the action of certain bacteria on sucrose? A-dextrins B-dextrans C-inulin D-agar 8-which of the following is true about glycogen? A-formed from α-glucose subunits but it less branched than starch. B-contain only α 1-4 glucosidic linkage C-liver glycogen used during starvation D-muscle glycogen used to maintain blood glucose level 9-the difference between muscle and liver glycogen is? A-muscle glycogen fate is lactic acid B-liver glycogen affected during muscular exercise C-muscle glycogen affected during starvation D-all of the above is true 10-which of the following is reducing sugars? A-glucose-mannose-starch B-glucose-trehalose-galactose C-glycogen-galactose-sucrose D-galactose-mannose-isomaltose 78 Khaled Elshamy 11-the most abundant CHO found in nature is? A-starch B-glycogen C-cellulose D-Inulin 12-which of the following is true about Cellulose? A-non branching and formed of β-glucose subunits B-insoluble in water C-can’t be digested in our body. D-all of the above 13-which of the following polysaccharide found in the form of fibers? A-starch B-glycogen C-cellulose D-Agar 14-which of the following is polymer of fructose and used to asses GFR? A-inulin B-agar C-pectin. D-starch 15-which of the following is polymer of galactose? A-starch B-inulin. C-Agar-Agar D-Gums 16-which of the following used as a culture medium for bacterial growth? A-inulin B-Agar C-pectin D-starch 17-which of the following enter in the structure of gums? A-Glucose and fructose B-arabinose and glucose C-arabinose and galactose D-fructose and galactose 79 Khaled Elshamy 18-which of the following contain α-1-4 D-galactouronic acid linkage and used in TTT of infantile diarrhea? A-Gums B-pectins C-cellulose D-Agar 19-which of the following is true about GAGS? A-formed of repeating disaccharide(acidic sugar – amino sugar). B-GAGS is negatively charged due to sulfate group and uronic acid C-the acidic sugar is glucouronic acid or its epimer L-iduronic acid. D-All of the above 20-the difference between Mucoproteins and glycoproteins is? A-mucoproteins contain GAGS but glycoprotein not. B-the length of CHO chain is longer in mucoproteins. C-mucoproteins contain sulfate group and uronic acids but glycoproteins not. D-All of the above is true 21-which of the following GAGS not contain uronic acid? A-heparin. B-chondrotin sulfate C-keratan sulfate D-hyaluronic acid 22-which of the following GAGs found in cornea? A-heparin B-chondrotinsulfate C-keratansulfate-1. D-hyaluronicacid. 23-the most abundant GAGs is? A-heparin. B-chondrotinsulfate C-keratansulfate D-hyaluronicacid 80 Khaled Elshamy 24-the most heterogenous type of GAGs is? A-hyaluronicacid. B-chomdrotinsulfate. C-keratansulfate D-heparin 25-which of the following GAGs found in basement membrane? A-heparin. B-heparan sulfate C-hyaluronic acid D-dermatan sulfate 26-which of the following GAGs not sulfated and found in bacteria? A-hyaluronicacid B-dermatansulfate C-chodroitinsulfate. D-heparin 27-which of the following GAGs is highly sulfated? A-hyaluronic acid B-heparin C-heparan sulfate D-chondroitin sulfate 28-which of the following GAGs contain α-linkage? A-chondroitin sulfate. B-heparin C-hyaluronic acid D-keratan sulfate 29-which of the following GAGs found in mitral valve? A-chondroitin sulfate B-haparan sulphate C-keratan sulfate D-dermatan sulfate 30-the only GAGs found intracellular is ? A-condroitin sulfate B-heparan sulfate C-heparin D-dermatan sulfate 81 Khaled Elshamy LIPID 82 Khaled Elshamy 1-Which of the following is false about lipids? A-they are heterogeneous. B-soluble in polar solvents C-lighter than water D-soluble in benzene 2-Which of the following is false about depot fat? A-enter in the Assue structure B-Contain large amount of cholesterol and PL but Small amount of TAGs C-act as heat insulator D-not aﬀected by starvaAon 3-Which of the following is true about depot fat? A-support internal organs as kidney. B-source of 7-dehydrocholesterol which is precursor for VIT D3. C-act as heat insulator and consumed during starvaAon. D-all of the above 4-which of the following is false about lipid importance? A-contain essenAal faOy acids B-contain Fat soluble vitamins C-act as electrical insulator D-source of energy gives 4kcal/g 5-which of the following not considered derived lipid? A-Glycerol B-cholesterol C-faOy acids D-ascorbic acid 83 Khaled Elshamy 6-which of the following is false about butyric acid? A-saturated faOy acid B-solid at room temperature C-contain 4C D-non essenAal amino acid 7-which of the following is saturated faOy acid? A-linoleic B-oleic acid C-arachidonic acid D-stearic acid 8-Condensed structural formula of caproic acid is? A-CH3-CH2-CH2-COOH B-CH3-(CH2)4-COOH C-CH3-(CH2)14-COOH D-CH3-(CH2)16-COOH 9-Which of the following is true? A-Palmitoleic faOy acid is delta-9 and omega-9 B-oleic acid is delta-9 and omega-7 C-linoleic is delta-9,12 and omega 6 D-linolenic is delta-6,9,12 and omega-6 10-which of the following is true about arachidonic acid? A-precursor of prostaglandin B-formed from 20c C-may considered semi-essenAal faOy acid D-all of the above 11-which of the following is an essenAal faOy acid? A-butyric acid B-linoleic C-arachidonic acid D-palmitoleic acid 84 Khaled Elshamy 12-which of the following is true about TAGs? A-they formed of 3 F.A and glycerol B-they are neutral C-could be oils or fats according to their double bond content D-all of the above 13-In mammals, the major fat in adipose Assue is? A-phospholipid B-TAGs C-cholesterol D-sphingolipid 14-which of the following is correct about iodine value? A-it’s a property of ester bond B-its number of milligram of iodine taken by 100 gram of fat C-it determine the length of faOy acid D-fat rich in linolenic acid have iodine number than those rich in butyric acid 15-which of the following is true about hydrogenaAon of TAGs? A-it means conversion of unsaturated faOy acid to saturated faOy acids B-trans unsaturated faOy acids lead to atherosclerosis C-complete hydrogenaAon of linoleic lead to formaAon of stearic acid D-all of the above 16-heaAng TAGs with alkali lead to formaAon of Glycerol and soap? A-true B-false 85 Khaled Elshamy 17-hydrolysis of TAGs by lipase enzyme lead to formaAon of glycerol and 3 faOy acids? A-true B-false 18-which of the following is true about saponiﬁcaAon value? A-it is a property of double bond B-it determine degree of unsaturaAon of oils C-it means number of grams of KOH required to saponify one gram of fats D-TAGs rich in butyric acid have saponiﬁcaAon value higher than which contain linoleic acid 19-which of the following is true about rancidity? A-TAGs which have higher iodine value have higher liability to rancidity B-TAGs which do complete hydrogenaAon have lower liability for rancidity C-TAGs which contain arachidonic acid are liable for rancidity than which contain butyric acid. D-all of the above 20-which of the following anAoxidant is needed to prevent rancidity? A-ascorbic acid B-copalamine C-thiamine D-niacin 21-rancidity means oxidaAon of fats or oils and it’s a property of ester bond? A-true B-false 86 Khaled Elshamy 22-bee wax formed of myricyl alcohol and palmiAc acid? A-True B-false 23-which of the following is false about waxes? A-Thay contain one faOy acid B-may be solid or liquid C-have no nutriAonal value D-cannot be digested 24-which of the following is true about phospholipids? A-they are amphipathic compounds B-enter in the structure of lipoprotein C-enter in the structure of cell membrane D-all of the above 25-which of the following phospholipid enter in the structure of lung surfactant? A-lecithin B-cephalin C-phosphaAdylserine D-phosphaAdylethanolamine 26-phosphaAdylethanolamine(cephalin) enter in the structure of brain and nerves? A-true B-false 27-which of the following is false about glycerophospholipid? A-back bone is glycerol B-phosphaAdic acid is the precursor C-cephalin is an example on It D-sphingomylein is an example on it 28-which of the following is true about cardiolipin? A-contain 3 glycerol molecule in its structure B-maintain ETC complexes C-found in bacteria and eukaryotes D-all of the above 87 Khaled Elshamy 29-which of the following is true about plasmalogens? A-contain ether linkage in its structure B-formed when C1 aOached faOy acid in phospholipid is replaced by unsaturated alkyl group C-phosphaAdal-ethanolamine and phosphaAdal-choline is an example D-all of the above 30-which of the following is true about platelet acAvaAng factor? A-formed when C1 aOached faOy acid in phospholipid replaced by saturated alkyl group and C2 F.A replaced by acetyl residue. B-contain ether linkage C-it acAvate inﬂammatory cells and mediate hypersensiAvity D-all of the above 31-which of the following is true about sphingophospholipid? A-back bone is sphingosine B-sphingomylein formed from ceramide + phosphorylcholine. C-ceramide also serve as precursor for glycolipid. D-all of the above 88 Khaled Elshamy 32-which of the following is true about lipoprotein? A-they are amphipathic compounds B-their core formed of TAGs and CE and the outer shell formed of PL and apoprotein and free cholesterol. C-CM-VLDL-LDL-HDL is an examples. D-all of the above 33-which of the following is true about lipoproteins funcAon? A-CM is responsible for transport of endogenous TAGs B-VLDL is responsible for transport of exogenous TAGs C-LDL is responsible for TAGs transport D-HDL is responsible for reverse cholesterol transport 34-which of the following lipoprotein protect against coronary heart disease? A-CM B-VLDL C-LDL D-HDL 35-which of the following is true about cholesterol? A-present only in animals B-enter in the structure of cell membrane C-enter in the structure of bile salts, VIT D3 and steroid hormones D-all of the above 89 Khaled Elshamy PROTEIN 90 Khaled Elshamy 1-All proteins contain? A-same 20 amino acids B-diﬀerent amino acids C-300 amino acids occurring in nature D-only a few amino acids 2-proteins contain? A-only L-α-amino acids B-only D-amino acids C-D and L amino acids D-none of the above 3-the opDcally inacDve amino acid is? A-glycine B-serine C-threonine D-valine 4-At neutral PH, a mixture of amino acids in soluDons would be predominantly? A-dipolar ions B-non polar molecules C-posiDve and monovalent D-hydrophobic 5-which of the following is true about amino acids at physiological PH? A-all amino acids contain both posiDve and negaDve charge B-all amino acids contain posiDvely charged side chain C-all amino acids contain negaDvely charged side chain D-none of the above 6-sulfur containing amino acid is? A-methionine B-serine C-valine D-asparagine 91 Khaled Elshamy 7-an aromaDc amino acids is? A-lysine B-tyrosine C-Arginine D-taurine 8-an amino acids that does not form α-helix is? A-valine B-proline C-tyrosine D-tryptophan 9-which of the following is an essenDal amino acids? A-aspartate B-tyrosine C-methionine D-serine 10-non essenDal amino acids? A-are not component of Dssue protein B-may be synthesized in the body from essenDal amino acids C-have no role in metabolism D-may be synthesized in the body in diseased state 11-which of the following is semi essenDal amino acid? A-valine B-arginine C-lysine D-tyrosine 12-an example of polar amino acid? A-alanine B-leucine C-arginine D-valine 13-the amino acid with non polar side chain? A-serine B-valine C-asparagine D-threionine 14-A ketogenic amino acid? A-valine B-cysDne C-leucine D-threionine 92 Khaled Elshamy 15-an example of metalloprotein? A-casein B-ceruloplasmin C-gelaDn D-salmine 16-an example of chromoprotein? A-hemoglobin B-sturine C-nuclein D-gliadin 17-casein, the milk protein is? A-nucleoprotein B-chromoprotein C-phosphoprotein D-glycoprotein 18-each turn of alpha helix contain …. Amino acids? A-3,6 B-3,4 C-4,2 D-4,5 19-TerDary structure of protein describe…..? A-the order of amino acids B-locaDon of disulphide bond C-loop regions of proteins D-the ways of protein folding 20-alpha helix and beta pleated sheet is an example of … structure of protein? A-primary B- secondary C-terDary D-quaternary 21-the basic amino acids are? A-lysine B-glycine C-leucine D-valine 22-DenaturaDon of proteins results in? A-disrupDon of 1ry structure B-breakdown of pepDde bond C-destrucDon of hydrogen bond D-irreversible change of the molecule 93 Khaled Elshamy 23-at isoelectric point an amino acid exists as? A-anion B-caDon C-zwiUerion D-none of the above 24-A disulphide bond can be formed between? A-two cysteine B-two methionine C-methionine and cysteine D-all of the above 25-A coagulated protein is? A-insoluble B-biologically non funcDoning C-un folded D-all of the above 26-at a PH below isoelectric point an amino acid exist as? A-caDon B-anion C-zwiUerion D-none of the above 27-the acidic amino acid at isoelectric point carry negaDve charge? A-true B-false 28-the neutral amino acid at PH above isoelectric point carries negaDve charge? A-true B-false 29-which of the following is the alpha helix terminator? A-alanine B-valine C-proline D-gluamate 30-ElectrostaDc bond can be formed between? A-valine and glycine B-arginine and glutamate C-methionine and cysteine D-arginine and lysine 94 Khaled Elshamy 31-Glutelins are present in? A-milk B-eggs C-meat D-cereals 32-which of the following amino acids found a lot in gliadins and glutenins? A-serine B-therionine C-glutamate D-glycine 33-Gliadins and glutenins soluable in alkalies? A-true B-false 34-two amino groups are present in? A-leucine B-lysine C-glycine D-glutamate 35-which of the following Is a mixed gluco and ketogenic amino acid? A-phenylalanine B-glycine C-glutamate D-proline 36-All of the following are branched chain amino acids except? A-isoleucine B-valine C-leucine D-arginine 37-An hydroxy containing amino acid is..? A-serine B-isoleucine C-alanine D-tryptophan 38-which of the following is an essenDal amino acid? A-cysDene B-leucine C-tyrosine D-aspartate 39-this amino acids cannot have opDcal isomers? A-alanine B-hisDdine C-proline D-glycine 95 Khaled Elshamy 40-which of the following amino acids can be found on the surface of protein during protein folding? A-glycine B-proline C-glutamate D-leucine 41-the amino acid which contains a guanidine group is? A-hisDdine B-arginine C-proline D-alanine 42-the amino acid which contain imidazole ring? A-arginine B-hisDdine C-ornithine D-proline 43-an amino acid which contain disulphide bond? A-cysteine B-cysDne C-methionine D-glycine 44-which of the following is 2ry amino group so called imino acid? A-lysine B-proline C-glycine D-arginine 45-all amino acids have one asymmetric carbon except? A-arginine B-proline C-glycine D-alanine 46-α-helix is disrupted by certain amino acids as..? A-proline B-arginine C-hisDdine D-lysine 47-alpha helix is stabilized by? A-hydrogen bond B-disulphid bond C-salt bond D-none of the above 48-isoelectric point of amino acids is used for …? A-crystalizaDon B-percipitaDon C-soluability D-reacDvity 96 Khaled Elshamy 49-terDary structure of protein is determined by? A-hydrogen bond B-disulphide bond C-electrostaDc bond D-all of the above 50-all of the following about protein denaturaDon is true except? A-loss of 1ry , 2ry ,3ry , 4ry structure B-loss of biological acDvity of protein C-strong acids cause protein denaturaDon D-denaturated protein is easily precipitated 97 Khaled Elshamy ENZYMES 98 Khaled Elshamy 1-Enzymes increase the rate of chemical reac4on by? A-increase the velocity of the reac4on. B-change the free energy of the reactant and product. C-increase the free energy of ac4va4on. D-change the equilibrium of the reac4on they catalyze. 2-the michaelis constant KM is? A-the maximum velocity that any enzyme can achieve B-the substrate concentra4on that gives the best enzyme assay for an enzyme reac4on C-the substrate concentra4on when the reac4on is half the way towards the maximum velocity of the reac4on D-none of the above 3-lock and key model of enzyme ac4on proposed by ﬁsher implies that? A-the ac4ve site is ﬂexible and adjusts the substrate B-the ac4ve site requires removal of PO4 group C-the ac4ve site is complementary in shape to the substrate D-substrate change conforma4on prior to ac4ve site interac4on 4-lock and key theory can explain the reac4on of urease only on urea? A-true B-false 99 Khaled Elshamy 5-A major characteris4c propriety of an enzyme is that? A-binds substrate molecule B-consists of amino acids that are always close together in 1ry structure C-binds uncompe44ve inhibitor D-binds other enzymes 6-Enzyme ac4vity is controlled by? A-PH B-temperature C-enzyme and substrate Conc D-all of the above 7-Enzymes catalyzing reac4ons of intramolecular transfer of various groups are included into class of? A-hydrolases B-isomerases C-transferases D-oxidoreductases 8-DNA polymerase enzyme belong to transferases? A-true B-false 9-lipase enzyme belongs to ligases? A-true B-false 10-which of the following is not true regarding enzymes? A-they catalyze only a par4cular type of reac4on B-they remain ac4ve even aWer separa4on from the substrate C-they are destroyed aWer comple4on of the reac4on they catalyze D-they are irreversibly destroyed at high temperature 100 Khaled Elshamy 11-which of the following un protein part which binds 4ghtly with an apoprotein? A-Coenzyme B-prothe4c group C-sodium ions D-none of the above 12-what is the name of the enzyme that transfer phosphate group? A-methyl transferase B-kinase C-transketolase D-none of the above 13-Enzymes catalyse the synthe4c reac4on with ATP u4liza4on belongs to? A-transferases B-isomerases C-ligases D-lyases 14-enzymes that use NAD and FAD as a coenzyme belongs to? A-transferases. B-oxidoreductases C-ligases D-hydrolases 15-synthase enzyme belong to ligases but synthetase enzyme belongs to transferases? A-true B- false 16-what is the curve that describe mechaelis-menten equa4on? A-sigmoid curve B-double reciprocal plot C-hyperbolic curve D-none of the above 17-Enzymes catalyzing the reac4on of CO2 incorpora4on and releasing belongs to? A-transferases B-ligases C-isomerases D-lyases 101 Khaled Elshamy 18-which of the following class of enzyme cause no change in the molecular weight of its substrate aWer conver4ng it to product? A-lyases B-oxidoreductases C-isomerases D-ligases 19-what phenomenon of enzyme catalysis occur under a low temperature? A-reversible inac4va4on B-irreversible inac4va4on C-sedmenta4on D-none of the above 20-substrate induces a conforma4onal changes in the cataly4c site? A-lock and key model B-ﬂexible model of cataly4c ac4vity C-rigid model of cataly4c ac4vity D-none of the above 21-which of the following forms a part of coenzyme? A-Zn B-lipase C-Vit B D-lysine 22-when the substrate concentra4on equal to KM? A-half of the enzyme saturated with substrate B-the reac4on velocity equal Vmax C-the reac4on velocity equal double Vmax D-enzyme is 25% saturated with substrate 23-the enzyme which catalyze conversion of glucose to glucose 6 phosphate is called mutase? A-true B-false 102 Khaled Elshamy 24-zymogens is a? A-vitamin B-enzyme precursor C-modulator D-hormone 25-Coenzyme is oWen a vitamin? A-true B-false 26-feedback inhibi4on of enzyme ac4on is aﬀected by? A-enzyme B-substrate C-ﬁnal product D- none of the above 27-Fa^y acid synthase enzyme is an example on simple enzyme? A-true B-false 28-in a plot of 1/V against 1/S for an enzyme catalyzed reac4on the presence of compe44ve inhibitor will alter? A-Vmax B-intercept on 1/v axis C-intercept on 1/s axis D-pka of the plot 29-compe44ve inhibitor and non compe44ve inhibitor shiW the curve to the leW? A-true B-false 30-which of the following increase the Vmax and KM constant? A-compe44ve inhibitor B-non compe44ve inhibitor C-un compe44ve inhibitor D-enzyme addi4on 103 Khaled Elshamy 31-on lineweaver- burk plot if if the y-intercept shiWed upward Vmax will decrease? A-true B-false 32-on lineweaver-burk plot, if the x-intercept shiWed to the right which will occur? A-Vmax will increase B- KM will decrease C-Vmax will decrease D- KM will increase 33-a non compe44ve inhibitor of an enzyme? A-increase KM and Vmax B-decrease Vmax and KM constant C-decrease both KM and Vmax D-KM increase and Vmax constant 34-which of the following represents addi4on of un compe44ve inhibitor? 35-which one of the following statements correctly describes allosteric enzymes? A-eﬀector may enhance or inhibit substrate binding B-they are not controlled by nega4ve feed back inhibi4on 104 Khaled Elshamy C-michaelis-menten kine4cs describes their ac4vity D-Posi4ve coopera4vity occurs with all allosteric enzymes except hemoglobin 36-which of the following statements describes the allosteric enzymes? A-regulatory molecule binds to the ac4ve site B-regulatory molecule alter the equilibrium not the ac4vity C-their curve is hyberbolic curve D-binding of the substrate to one site can aﬀect the other sites 37-Isoenzymes for a given reac4on? A-have diﬀerent speciﬁcity B-have iden4cal aﬃni4es for the same substrate C-have diﬀerent electrophore4c ac4vity D-similar physically and chemically 38-the isoenzyme LDH-5 is elevated in? A-MI B-pep4c ulcer C-liver disease D-infec4ous disease 39-on the 3rd day of onset of acute MI the enzyme elevated is? A-CK-MM B-CK-MB C-LDH D-ALT 40-LDH1 and LDH2 elevated in? A-Myocardial infarc4on B-liver disease 105 Khaled Elshamy C-kidney disease D-brain disease 41-which of the following CK found in heart? A-CK-MM B-CK-MB C-CK-BB D-all of the above 42-mul4ble forms of the same enzyme are known as? A-zymogens B-isoenzyme C-pro-enzyme D-pre-enzyme 43-an allosteric enzyme inﬂuences the enzyme ac4vity by? A-compe4ng the cataly4c site with the substrate B-changing enzyme speciﬁcity for the enzyme for the substrate C-changing the conforma4on of the enzyme by binding t

BIOCHEMISTRY First Year Past Paper PDF

Document Details

Tags

Related

Summary

Full Transcript

Upgrade to continue