Biochemistry 🧪 Flashcards

Question

what are reducing disaccharides?

Answer 1

if one of aldehyde/or ketone groups is free (free anomeric C) e.g. Lactose and Maltose. Classification:

Answer 2

sucrose, lactose and maltose.

Answer 3

(malt sugar, maltose syrup)

Answer 4

2 alpha Dextro glucose - alpha 1 4 glycosidic bond (reducing)

Answer 5

It is formed of two α-glucose but linked together by α 1-6 glycosidic bonds. It is a reducing sugar.

Answer 6

It is formed of two units β-glucose linked together by a β1-4 glycosidic bond.

Answer 7

Formed of α-glucose and β-fructose linked by an α-1- β-2 glycosidic bond (involving the anomeric Cs). (non-reducing)

Answer 8

It is formed from β-galactose and β-glucose via a β (1-4) link with free anomeric C. It is a reducing sugar.

Answer 9

starch is hydrolyzed by pancreatic and salivary amylase giving maltose which is hydrolyzed by maltase giving two glucose units. starch is also be hydrolyzed by acids giving dextrins which are hydrolyzed by alpha dextrinase giving smaller units.

Answer 10

dextran is hydrolyzed into isomaltose

Answer 11

is ts hydrolyzed by acids into cellobiose.

Answer 12

it is hydrolyzed by sucrase into alpha glucose and beta fructose.

Answer 13

it is hydrolyzed by intestinal lactase into beta glucose and beta galactose

Answer 14

• It is the principal carbohydrate in milk and is of critical nutritional importance to mammals in the early stages of their lives. • It may appear in the urine in late pregnancy and during lactation • Low levels of lactase enzyme lead to undigested lactose that undergoes bacterial fermentation in the colon with the generation of large amounts of CO2, H2, and irritating organic acids. • These products cause painful digestive upsets known as lactose intolerance.

Answer 15

• Oligosaccharides consist of 3-10 monosaccharide units joined together by glycoside bonds. E.g. Maltotriose.

Answer 16

• Oligosaccharides are important as constituents of the glycolipids and glycoproteins of the cell membrane. • Many secreted proteins, such as antibodies and coagulation factors also contain oligosaccharide units.

Answer 17

• Polysaccharides, also called glycans, consist of more than 10 monosaccharide units and/or their derivatives joined together by glycosidic linkage.

Answer 18

according to structure and function

Answer 19

1. Homopolysaccharides (homoglycans): contain only one type of monosaccharide. E.g. starch, glycogen, dextran, dextrin, cellulose, inulin. 2. Heteropolysaccharides (heteroglycans): contain more than one type of monosaccharides. E.g. glycosaminoglycans (GAGs, mucopolysaccharides), agar.

Answer 20

Polysaccharides are classified according to their function into storage and structural polysaccharides. • Storage polysaccharides: starch, glycogen, dextran, and inulin. • Structural polysaccharides: cellulose and agar.

Answer 21

It is a glucosan (a-D glucose units) consists of 2 layers: ► An inner linear nonbranching layer called amylose. ► An outer highly branched layer is called amylopectin. The branch points occur about once every thirty linkages. -Main storage of polysaccharides in plants.

Answer 22

-Glucosan ►It is a highly branched molecule (branches every 10 glucose units; more branched than amylopectin). It yields a red-violet color with iodine. -Main storage of polysaccharides in humans and animals -It is present mainly in the liver 10% and in the skeletal muscles 1-2% and breaks down to glucose when fasting which helps in maintaining glucose levels in the blood.

Answer 23

-It is formed of α-glucose units (glucosan). -It is a storage polysaccharide in yeasts and bacteria -Bacterial dextrans are used in laboratories as the support medium for chromatography of macromolecules and as replacement therapy in blood loss. -Dental plaque is due to dextran synthesized from sucrose by oral bacteria.

Answer 24

-It is formed of β-D-glucose units. -It is the most abundant natural polymer found in the world. It is the structural component of the cell walls of nearly all plants. -Cellulose is extremely resistant to hydrolysis whether by acid or by the digestive tract amylases. So, it can stimulate peristaltic movement and prevent constipation. -The bacteria that live in the gut of ruminant animals secrete cellulase enzyme (β- glucosidase) which is effective in the hydrolysis of cellulose.

Answer 25

-It is formed of fructose (fructosan). -Hydrolyzed by the enzyme inulinase in plants. It has no dietary importance in human beings as inulinase is absent in human -It is used in the inulin clearance test to determine the rate of glomerular filtration. It can be used as a diet for diabetics.

Answer 26

Starch is partially hydrolyzed by acids or enzymes into dextrins and it is hydrolyzed by alpha dextrinase -It is used as mucilage.

Answer 27

agar GAGS (glycosaminoglycans - mucopolysaccharides)

Answer 28

• A polysaccharide isolated from marine red algae. • Composed of agarose and agaropectin • Agarose gel is used in gel chromatography and gel electrophoresis. • Nutrient agar is used in the preparation of culture media in microbiology

Answer 29

• GAGs are long linear unbranched chains composed of a repeating disaccharide unit (acidic sugar-amino sugar) . • The amino sugar: (D-glucosamine or D-galactosamine) and the amino group is usually acetylated (sometimes sulphated). • The acid sugar: either glucuronic or L-iduronic

Answer 30

-glucuronic acid -N-galactosamine (acetylated) -sulphated -cartilage, tendons, ligaments, bone, heart valves, aorta. -Most abundant GAG -protective and supportive.

Answer 31

-no uronic acid -N-glucosamine (acetylated) and galactose -6- sulfate -Sulfated -cornea, bone,cartilage -aggregated with chondroitin sulfate -protective and supportive

Answer 32

-L-iduronic acid -N-galactosamine (acetylated) -Sulfated -skin, blood vessels, heart valves -protective and supportive. Usually replaces hyaluronic acid in aged skin and blood vessels

Answer 33

-glucuronic and iduronic acid -Glucosamine (non-acetylated) -More Sulfated -Intracellular granules of mast cells lining the arteries of the lungs, liver and skin -Anticoagulant

Answer 34

-glucuronic or iduronic acid -Glucosamine (acetylated) -Less Sulfated -Extracellular GAG, basement membranes of cell surface -components of the cell surface.

Answer 35

-glucuronic acid -Glucosamine (acetylated) -Non sulfated -synovial fluid of joints, vitreous humor of eye, skin ECM of loose connective tissue -shock absorbing, lubricant.

Answer 36

• All of the GAGs except hyaluronic acid and heparin are found covalently attached to a protein, forming proteoglycan monomers. •A proteoglycan monomer found in cartilage consists of a core protein to which the linear carbohydrate chains are covalently attached.

Answer 37

-The are the structural units of proteins, and they are obtained from proteins by acid,alkali or enzymatic hydrolysis.

Answer 38

All amino acids except proline and hydroxyproline consist of:- Carboxyl group COOH Amino group NH2 Side chain (Characteristic to each amino acid)

Answer 39

-The acid they are derived from. -The number of carboxyl and amino groups. -Their nutritional importance. -Their metabolism.

Answer 40

By the reaction between COOH group and NH2 associated with removal of water forming petide bonds.

Answer 41

-They are amino acids that can be converted into carbohydrates. And they are All except leucine,lysine,Isoleucine,Tyrosine,Tryptophan and Phenyl alanine.

Answer 42

-They are amino acids that can be converted into ketone bodies like Leucine.

Answer 43

-They are amino acids that can be converted to both carbohydrates and ketone bodies like Isoleucine,Lysine,Phenylalanine,Tyrosine and tryptophan

Answer 44

-Essential amino acids: They are amino acids that are not synthesized in the body and must be taken in diet. -Non-Essential: they are amino acids that are synthesized in the body and there is no need to be taken in diet “VILAr HM= Ten THousand Pounds” Valine Isoleucine Lysine Leucine Arginine Histidine Methionine Tryptophan Threonine Phenylalanine And anything else is non-essential

Answer 45

They are amino acids in which the number of amino groups is more than the number of carboxylic groups like Ar - H - Ly Arginine Histidine Lysine

Answer 46

-They are amino acids in which the number of carboxylic groups is more than the number of amino groups. Glutamic acid Aspartic acid

Answer 47

-They are amino acids in which the number of carboxylic groups equal the number of amino groups. Aliphatic (Gavil): glycine-Alanine-Valine-Isoleucine-Leucine Containing hydroxyl(TTSH): Tyrosine-Threonine-Serine Containing sulphur(CCM): Cystine-Cysteine-Methionine Aromatic amino acids(TTPh):Tyrosine-Tryptophan-phenylalanine Heterocyclic amino acids: proline-hydroxyproline

Answer 48

Alanine Serine Cystine Cysteine Phenylalanine Tyrosine Tryptophan Histidine

Answer 49

Threonine Methionine

Answer 50

Isoleucine Valine

Answer 51

Glutamic acid Aspartic acid

Answer 52

Proline Hydroxy proline

Answer 53

Valine, isoleucine and leucine

Answer 54

- Reaction due to both NH2 and COOH group: Amino acids condenese with each other by COOH group at one amino acid with of other amino acid to form peptide bond. If 3 amino acids condense together they form Tripeptide and so on,,,,,

Answer 55

Organic complex nitrogenous compounds of high molecular weight formed of C, H, O, N [N= 16%].

Answer 56

1) Antibodies (immunoglobulin) are proteins 2) Buffer system of blood (plasma proteins). 3) Carry hormones and minerals in blood (plasma proteins), Carry oxygen (Hemoglobin). 4) Structure of cell membrane. 5) Support bone, skin, nails, and hair. 6) Hormones as insulin. 7) Enzymes are proteins.

Answer 57

1) According to shape 2) According to Nutritional value 3) According to their chemical structure

Answer 58

Fibrous and globular

Answer 59

-Long, narrow fibers -More than 10 -Insoluble -More stable -Actin, Myosin, collagen

Answer 60

-Rounded (spherical) -Axial ratio Less than 10 -Soluble -Less stable -Albumin, hemoglobin, insulin

Answer 61

-nutritionally rich proteins--->contain all the essential amino acids. -incomplete proteins---->Lack one essential amino acid. -poor proteins---->Lack many essential amino acids.

Answer 62

1-caseinogen(protein of milk) 2-proteins of pulses lack methionine, proteins of cereals lack lysine. 3- zein of maize protein lacks lysine and tryptophan.

Answer 63

-simple, compound, and derived.

Answer 64

On hydrolysis, they produce only amino acids.

Answer 65

The first six are globular. 1-albumin 2-globulin 3-Glutillin 4-Prolamin 5-Protamin 6-histones 7-albuminoids(scleroproteins)

Answer 66

Coagulated by heat -present in egg (egg albumin),blood (plasma albumin)and milk (lactoalbumin)

Answer 67

-Coagulated by heat -present in egg (egg globulin), blood (plasma globulin), milk (lactoglobulin)

Answer 68

as glutenin of wheat.

Answer 69

-as Zein of corn and maize. - deficient in tryptophan amino acid →

Answer 70

-Rich in basic amino acids. -found in combination with nucleus acid of Salomon.

Answer 71

-rich in basic amino acids. -found in combination with nucleic acids in human -found in globin of HB.

Answer 72

they are fibrous proteins. Insoluble in water ,dilute acids and alkali and all neutral solvents. Not digested by proteolytic enzymes. Found in animal tissues and having supportive and protective functions. Ex: A. Keratin:present in hair, nail B. Elastin: present in joints, wall of lung alveoli and ligaments C. CollageN:present in skin, bone, cartilage, and connective tissues

Answer 73

they are formed of protein and non-protein part.

Answer 74

-Glycoproteins -lipoproteins Phosphoproteins -metalloproteins -Chromoproteins(hemo and flavo) -Nucleoprotein

Answer 75

proteins are conjugated with carbohydrates  Ex: Hormones (FSH, LH), Enzymes.  Mucin of GIT.  Antibodies, blood group Antigen. .

Answer 76

proteins are conjugated with lipids. Ex: Chylomicrons VLDL LDL, HDL.

Answer 77

Proteins are conjugated with phosphoric acid. Ex: Caseinogen (main protein of milk).

Answer 78

Proteins are conjugated with metals. Ex: Ceruloplasmin (protein + Cu).  Insulin (protein + Zinc).  Ferritin (Fe)

Answer 79

-Hemoproteins -Flavoproteins

Answer 80

protein + heme (red pigment) as Hemoglobin and cytochromes (components of electron transport chain)

Answer 81

proteins + FAD (yellow color).

Answer 82

Proteins are conjugated with nucleic acids. Ex: Histone + DNA in chromosome. protein + RNA in Ribosome.

Answer 83

they are denaturated or hydrolytic products of simple or conjugated proteins .

Answer 84

Primary and secondary

Answer 85

result from of proteins from its native state without hydrolysis of peptide bond Ex:-meta which are produced by hydrolysis with a cid or alkali Coagulated which result from hydrolysis with heat

Answer 86

They are hydrolysis products of proteins. Proteomes: Products of partial hydrolysis of proteins Peptones: Products of proteoses hydrolysis. Peptides: Products of peptones hydrolysis.

Answer 87

There are four orders of protein structures: 1) Primary structure of Proteins 2) Secondary structure of Proteins 3) Tertiary structure of Proteins 4) Quaternary structure of Proteins

Answer 88

 Referred to the number, type, and sequence of amino acids in the polypeptide chain.  Any change in one of the amino acids in the polypeptide chain produces a physiological defect.  The main bond in this structure is the peptide bond.  The free -NH2 group of the 1st amino acid is called as N-terminal end and the free - COOH end of the last amino acid is called as C-terminal end.

Answer 89

The polypeptide chain will be folded to give a specific shape form which may be: a) α-Helix b) β-pleated Sheets c) Supersecondary structures(motifs)

Answer 90

 The polypeptide chain is twisted to a right-handed coiled helix.  each turn contains 3.6 amino acids, which is a common secondary structure in globular proteins.  The formation of the α-helix is spontaneous and is stabilized by Hydrogen bonds between carbonyl Oxygen of peptide bond and hydrogen of NH of the next 4th peptide bonds in the chain.

Answer 91

 Formed when hydrogen bonds are formed between two or more adjacent polypeptide chains.  The hydrogen bonds are inter-chain.  It is pleated due to the angles of bonds.

Answer 92

 Combinations of α-helix and β-sheets to form a specific shape.  It gives protein a specific structure feature to enable a particular function.  EX: Helix-turn-helix (HTH)  Two α helices are joined by a short strand of amino acids.  Is a major structural motif capable of binding DNA.

Answer 93

 Secondary structures are arranged to form a final functional 3D structure called domain.  It occurs due to interaction between side chains (R) of the amino acids. domain.  There are forces controlling tertiary protein structure.

Answer 94

Hydrogen bond: Between polar side chains of amino acids. Hydrophobic forces: Between the non-polar (R) groups of the amino acids Electrostatic forces(ionic bonds, salt bridges): Between oppositely charged (R) groups of amino acids Disulfide bonds: Between sulfur amino acids (cysteine)

Answer 95

 Special arrangement of more than one polypeptide chain (subunits = monomers).  The bonds: Non-covalent (hydrogen or ionic bonds)  This high level of organization is essential for the activity of some proteins like hemoglobin, enzymes.

Answer 96

-Creatine kinase (CK) enzyme is a dimer. - Haemoglobin and lactate dehydrogenase (LDH) enzymes are tetramers.

Answer 97

It is a physical and dynamic process by which a string of amino acids interacts with itself to form a stable three-dimensional (3D) structure during the production of the protein within the cell.

Answer 98

1) Production of protein structures that can perform specific functions in the cell. 2) Prevent non-specific interaction of the protein with other proteins (prevent protein aggregation).

Answer 99

Occurs spontaneously, but there is a class of specialized proteins; chaperones, whose function is to assist in this process.

Answer 100

1-Spontaneous 2-Mutation in a particular gene, which then produces an altered protein. 3-Some proteins after abnormal proteolytic cleavage can take on a unique conformational state that leads to the formation of long fibrillar protein assemblies consisting of β pleated sheets (its accumulation →Amyloidosis).

Answer 101

There is a deposition of misfolded proteins as insoluble aggregates within the cell.

Answer 102

Alzheimer’s disease: deposits of amyloid-beta and tau. Type II diabetes: deposits of amylin. Parkinson’s disease: deposits of alpha-synuclein.

Answer 103

Disruption of the secondary, tertiary, and wherever applicable quaternary organization of a protein molecule due to cleavage of non-covalent bonds. N.B: The primary structure of protein molecule is not affected, i.e. peptide bond is not affected

Answer 104

Physical: 1) Heat 2) UV light 3) Ultrasound 4) Hight pressure 5) Violent shaking Chemical: 1) Strong acids 2) Strong alkalies 3) Organic solvents 4) Heavy metal salts

Answer 105

 Medical supplies and instruments are sterilized by heating to denature proteins in bacteria and thus destroy the bacteria.  The acid gastric juices cause the denaturation of protein.  70% alcohol solution is used as a disinfectant on the skin. This concentration of alcohol is able to penetrate the bacterial cell wall and denature the proteins and enzymes inside of the cell.

Answer 106

- Chemical:  Unfolding of the protein molecule.  Destruction of some subsidiary hydrogen bonds.  Exposure of some groups as (SH) of cysteine. - Biological:  Loss of activity if it is a hormone or enzyme.  Easily digested.

Answer 107

❖ Lipids are compounds that are relatively insoluble in water, but freely soluble in non-polar organic solvents like benzene, ether, and acetone, etc.

Answer 108

1) Storage form of energy (triglycerides). 2) Structural components of membranes (phospholipids and cholesterol). 3) Metabolic regulators (e.g. steroid hormones). 4) Help in the absorption of fat-soluble vitamins (A, D, E, and K). 5) Protect internal organs by providing a cushioning effect (pads of fat). 6) Provide insulation against changes in external temperature (subcutaneous fat). 7) Act as electric insulators in neurons.

Answer 109

1) Simple lipids: ❖ They are formed of fatty acids and alcohol. ❖ They are further classified according to the type of alcohol present into:  Fats and oils.  Waxes. 2) Compound lipids: ❖ They are formed of simple lipids and another non-lipid part. 3) Derived lipids: ❖ They are substances derived from simple lipids and compound lipids by hydrolysis. ❖ They also include substances related to lipids and associating lipids in nature.

Answer 110

It is polyhydric alcohol containing 3 OH groups.

Answer 111

It is used in pharmaceutical (e.g. glycerin suppositories) and cosmetic preparations. It is used as a vasodilator agent in coronary heart disease in form of nitro-glycerine.

Answer 112

❖ Fatty acids are usually monocarboxylic straight aliphatic chains with a methyl group at one end (called the ω-carbon) and a carboxyl group at the other end. ❖ It is the most common component of lipids in the body. ❖ They are generally found in ester linkage in different classes of lipids

Answer 113

1) C-system numbering starts from the carboxyl-terminal: 2) ω-system numbering starts from the methyl end:

Answer 114

Even chain:  They have carbon atoms 2, 4, 6, and similar series.  Most of the naturally-occurring lipids contain even chain fatty acids. Odd chain:  They have carbon atoms 3, 5, 7, etc.

Answer 115

Acc. To total number of carbon atoms in the chain Acc. To the length of the hydrocarbon chain Acc. To the nature of the hydrocarbon chain

Answer 116

-Short with 2 to 6 carbon atoms. -medium with 8 to 14 carbon atoms. -long with 16 to 22 carbon atoms. -very long with more than22 carbon atoms.

Answer 117

❖ Saturated fatty acids. ❖ Unsaturated fatty acids: May be sub-classified into: Mono-unsaturated (mono-enoic)  having a single double bond. Polyunsaturated (poly-enoic)  with 2 or more double bonds.

Answer 118

Acetic 2 Butyric 4 Caproic 5 Palmitic 16 Stearic 18 Propionic 3 Valeric 5

Answer 119

Palmitoleic (16: 1∆9, W7) Oleic (18: 1∆9, W9) Nervonic (24: 1∆15, W9)

Answer 120

3S-2C-ON ❖ Common sources: Many vegetable oils: sunflower, olive, nuts, corn, sesame, soybean, and cod liver oils.

Answer 121

❖ They are fatty acids that contain more than one double bond. ❖ They must be taken into the diet because the body cannot synthesize them as the enzymes needed for their synthesis are absent in humans.

Answer 122

Many vegetable oils: sunflower, olive, nuts, corn, soybean, and cod liver oils.

Answer 123

 They are essential for growth.  They are essential for phospholipid formation  Important for prostaglandins biosynthesis.

Answer 124

Linoleic (18: 2∆9,12, W6) Linolenic (18: 3∆9,12,15, W3) Arachidonic. (20: 4∆5,8,11,14, W6)

Answer 125

They are esters of fatty acids with various alcohols. The alcohol may be glycerol or other than glycerol.

Answer 126

They are classified into fats, oils, and waxes, according to the type of alcohol they contain.

Answer 127

(triglycerides = triacylglycerol)

Answer 128

They are esters of fatty acids with glycerol. The fatty acids may be the same forming simple triglycerides e.g. palmitic or stearic acids forming tripalmitate or tristearate respectively, or they may be different forming mixed triglycerides with 3 different fatty acids.

Answer 129

because they are triesters formed of glycerol and 3 fatty acids

Answer 130

1) Storage of energy as fat:  The triacylglycerols are the storage form of lipids in the adipose tissue. 2) Provide essential fatty acids. 3) Carriers of fat-soluble vitamins (A-D-E-K).

Answer 131

They are esters of fatty acids with a long-chain monohydric alcohol.

Answer 132

-The most commonly known animal wax is beeswax -One of the most important waxes in plasma and tissues is cholesterol esters (cholesterol wax). -Cerumen (earwax) from the ceruminous glands in ears.

Answer 133

❖ Fatty acids + alcohol + other groups. ❖ They are classified according to the other group into:  Phospholipids: phosphoric acids  Glycolipids: Sugars  Sulfolipids: sulfate  Lipoproteins: proteins

Answer 134

❖ Alcohol + fatty acids + phosphoric acid ± nitrogenous base.

Answer 135

Glcrolphospholipids (phosphoglycerides) : Glycerol Sphingophospholipids (sphingomyelin) : Sphingol (sphingosine)

Answer 136

1. phosphatidic acid: Glycerol + 2 fatty acids +Phosphoric acid (No base) 2. Lecithin (Phosphatidylcholine): Phosphatidic acid + choline base. 3. Cephalin (phosphatidylserine or ethanolamine) :phosphatidic acid + serine or ethanolamine 4. Phospatidyl Inositol (Lipoinositol): phosphatidic acid + Inositol.

Answer 137

❖ Sphingol + unsaturated fatty acid + phosphoric acid + choline.

Answer 138

They are amphipathic (hydrophilic part + hydrophobic part) which helps:  Formation of the lipid bilayer in the cell membrane.  Micelle formation to help T.G absorption in the small intestine  The structure of plasma lipoprotein carries lipids in the blood. 2) Di-palmitoyl lecithin (DPL) is a component of lung surfactant (prevent lung collapse). 3) Lecithin is a lipotropic agent (prevent fatty liver). 4) Membrane phospholipids provides arachidonic acid for the synthesis of prostaglandins, leukotrienes. 5) Essential for blood clotting as platelet-activating factor (PAF) is choline plasmalogen 6) Phosphatidylinositol bisphosphate (PIP2) is 2nd messenger for hormones. 7) sphingomyelin is present in myelin sheath around nerves (electrical insulator

Answer 139

❖ Fatty acids + alcohol + sugar

Answer 140

-cerebrosides: ❖ sphingol+ fatty acid +monosaccharide usually galactose (Galacto-cerebrosides), may be glucose (Gluco-cerberosides) -gangliosides: ❖ sphingol + fatty acid + oligosaccharide chain

Answer 141

-Electrical insulator in nervous tissue. -Gangliosides are receptors for many hormones

Answer 142

as cerebrosides + sulfate group at C3 of galactose

Answer 143

present in the brain and nervous tissue.

Answer 144

- lipid part (Triglycerides T.G, cholesterol, phospholipids) - protein part (Apolipoprotein, may be α or β globulin)

Answer 145

- Structure of cell membrane - Lipid transport in the blood.

Answer 146

1) Chylomicrons (CM) 2) Very Low-Density Lipoprotein (VLDL) 3) Low Density Lipoprotein (LDL) 4) High Density Lipoprotein (HDL)

Answer 147

Lipids derived from simple lipids and compound lipids by hydrolysis (fatty acids, alcohol) or related to lipids (steroids)

Answer 148

Large group of biologically important compounds contain steroid nucleus.

Answer 149

They include: 1) Sterols 2) Steroid hormones 3) Vitamin D 4) Bile acids

Answer 150

Cholesterol and ergosterol

Answer 151

Exogenous (dietary cholesterol): - butter, cream, milk, egg yolk, and meat. Endogenous: Synthesized in the body

Answer 152

- It is widely present in body tissues. - largest amounts in brain, liver, skin, small intestinal, and adrenal cortex

Answer 153

Normal level of total cholesterol is below 200 mg/dl.

Answer 154

atherosclerosis, myocardial infarction and cerebral stroke.

Answer 155

- Free Cholesterol - Cholesterol ester (70%), linked with fatty acids (75% of cholesterol is carried in LDL, the reminder in HDL)

Answer 156

❖ Glucocorticoids (21 C): - Corticosterone & Cortisol (17-OH corticosterone) ❖ Mineralocorticoids (21 C): - 11-Deoxy corticosterone (DOC) - 11 deoxy cortisol - Aldosterone (most active)

Answer 157

- Vitamin D3: derived from 7-dehydrocholesteorl by U.V rays. - Vitamin D 2: derived from ergosterol by U.V rays.

Answer 158

increase Ca absorption from GIT and increase bone ossification

Answer 159

❖ Bile acids unit with glycine (glycocholic acid) or taurine (taurocholic acid). ❖ Glycocholic acid and Taurocholic acid + Na or K → Na or K -glycocholate and taurocholate (bile salts).

Answer 160

En= inside Zyme=yeast Enzymes are organic thermo-labile catalysts.

Answer 161

catalyst is a substance that increases the chemical reaction without change (not consumed, not affect the end product). They accelerate the chemical reactions inside the biological systems (living cells).

Answer 162

All enzymes are protein in nature except ribozymes (RNA in nature).

Answer 163

1) Simple protein enzymes: They are formed of protein only. 2) Complex (conjugated) protein enzymes: formed of two parts

Answer 164

The protein part is called apoenzyme The Non-protein part is called the cofactor. The whole enzyme is called a holoenzyme.

Answer 165

A restricted region of an enzyme molecule that binds to the substrate.

Answer 166

It is formed from Amino acids sequences in the polypeptide chain.

Answer 167

1) The substrate (S) binds to the enzyme (E) to form an activated intermediate enzyme-substrate complex (ES). 2) The activated complex (ES) cleaved to the products (P) and the original enzyme (E).

Answer 168

In complex enzymes, the coenzyme helps the cleavage of the substrate.

Answer 169

1) Substrate approaches active site. 2) Enzyme-substrate complex forms. 3) Substrate transformed into products. 4) Products released. 5) Enzyme recycled.

Answer 170

Lock and key theory. (Proposed by Fischer in 1894) Induced fit theory.

Answer 171

❖ In this model, the active sites of the unbound enzyme are complementary (fit) in shape to the substrate. ❖ The substrate fits in this catalytic site in a similar way to lock and key. The key will only fit its own lock.

Answer 172

 It is a more flexible model.  The catalytic site of the enzyme is not complementary to the substrate.  The binding of the substrate to the enzyme induces changes in the shape of the catalytic site making it fitter for the substrate.

Answer 173

1- Effect of enzyme conc. 2- Effect of substrate conc. 3- Effect of temperature 4- Effect of PH 5- Concentration of coenzymes 6- Concentration of ion activators 7- Presence of enzyme inhibitors 8- Effect of time

Answer 174

The rate of enzyme action is directly proportional to the concentration of enzyme provided sufficient supply of substrate & constant conditions.

Answer 175

The rate of reaction increases as the substrate concentration increases up to a certain point at which the reaction rate is maximal (Vmax.) At Vmax, the enzyme is completely saturated with the substrate, then any increase in substrate concentration doesn't affect the reaction rate.

Answer 176

It is the substrate concentration that produces half the maximum velocity of enzyme (1/2 Vmax).

Answer 177

have high affinity to the substrate i.e. they act at maximal velocity at low substrate concentration.

Answer 178

Hexokinase which acts on glucose at low concentration (fasting state)

Answer 179

have low affinity to the substrate i.e. they act at maximal velocity at high substrate concentration. E.g. Glucokinase enzyme acts on glucose at high concentrations (fed state).

Answer 180

 The rate of reaction increases gradually with the rise in temperature until reaches a maximum at a certain temperature, called optimum temperature.  The optimum temperature is around 37°C in humans  After the optimum temperature, the rate of reaction decreases

Answer 181

due to the denaturation of the enzyme (60-65).

Answer 182

The effect of temperature on reaction rate is due to: a)Increase in temperature increases the initial energy of the substrate and thus decreases the activation energy. b) Increase of collision of molecules.

Answer 183

Each enzyme has an optimum PH at which its activity is maximal. Change of PH above or below optimum PH decrease rate of enzyme action

Answer 184

due to: 1) The enzyme activity depends on the ionization state of both enzyme and substrate which is affected by PH. 2) Marked change in PH will cause denaturation of the enzyme.

Answer 185

In the conjugated enzymes that need coenzymes, the increase in the coenzyme concentration will increase the reaction rate.

Answer 186

The increase in metal ion activator increases the reaction rate. Many enzymes are activated by ions: 1- Chloride ion activate salivary amylase 2- Calcium ions activate the thrombokinase enzyme

Answer 187

presence of enzyme inhibitor decreases or stops the enzyme activity

Answer 188

In an enzymatic reaction, the rate of reaction is decreased over time.

Answer 189

This is due to: a) The decrease in substrate concentration b) The accumulation of the products. c) The change in PH than optimum PH.

Answer 190

Iso = the same Different molecular forms of the enzyme, have the same catalytic activity.

Answer 191

Although they have the same catalytic activity, they are physically distinct & differ in: 1) Electrophoretic mobility (migration in an electric field). 2) Liability to inhibitors.

Answer 192

 Lactate dehydrogenase (LDH)  Creatine kinase (CK)  Acid phosphatase  Alkaline phosphatase

Answer 193

❖ LDH enzyme is a tetramer formed of (4) protein subunits, each subunit is called protomer. ❖ The subunits of LDH are of 2 types, H (heart) and M (muscle).

Answer 194

LDH 1 HHHH Myocardial infraction LDH 2 HHHM Myocardial infraction LDH 3 HHMM Leukemia LDH 4 HMMM Viral hepatitis LDH 5 MMMM Viral hepatitis

Answer 195

❖ CK enzyme is a dimmer formed of 2 protein subunits. ❖ The subunits of CK are of 2 types, B (brain) and M (muscle

Answer 196

CK BB BB Brain tumors CK MB BM Heart diseases CK MM MM Skeletal muscle diseases

Answer 197

1- True genetic variants (True isoenzyme)  may be produced by more than one gene; each gene produces one subunit 2- Multiple forms (post-translational modification)  Isoenzymes may be produced by the same gene, but the subunits undergo different post-translation modifications in different organs

Answer 198

Isoenzymes are important in the diagnosis of diseases and indication of the diseased organ

Answer 199

❖ Plasma contains many enzymes: Functional and non-functional plasma enzymes

Answer 200

 Higher in comparison to tissue  Have known functions  Always present in plasma  Liver  They decrease in liver diseases Ex:-  Clotting factors e.g. Prothrombin  Lipoprotein lipase  Pseudocholinesterase  Very low in comparison to tissue  No known functions  Absent from plasma  Different organs e.g. liver, heart, skeletal muscles, and brain  They increase in different organ diseases Ex:-  ALT, AST, Alkaline phosphatase  Acid phosphatase  Lipase

Answer 201

❖ Obstruction of the normal pathway. ❖ Increased permeability of cell membrane: as in tissue hypoxia. ❖ Cell damage with the release of its contents of enzymes into the blood.

Answer 202

ALT: Liver disease AST: Liver, heart disease CK: Brain tumors, Myocardial infarction, SM disease LDH: Myocardial infarction, Leukemia, Viral hepatitis Alk. Phosphatase: Obstructive liver disease, bone disease Acid phosphatase: Prostate cancer Amylase, lipase: pancreatitis