Biochemical Engineering

BIOCHEMICAL BIOCHEMICAL ENGINEERING Biochemical engineering  –   is concerned with conducting biological processes on an industrial scale, providing the link between biology and Chemical Engineering. It is concerned with 1. Study of the numerous fermentation process in which the production of alcohols, organic acids, glycerol, acetone and other substance are end product. 2. Study of certain aspect of food manufacturing processes such as the making of cheese, butter and pickles in which microbic agency takes a significant part. 3. Study of food conservation methods. 4. Study of biological waste disposal. Common Features of Biological System 1. Organism share a common physical structure in that the cell is the fundamental unit structure of living organism. 2. They share common chemical composition as shown by the present of protein, DNA and RNA. 3. They perform common metabolic activities; while these metabolic or chemical activities differ in detail, the resemblance are more than the differences. Biochemical Industries: 1. Food Industries 2. Pharmaceutical Industry

3. Brewery And Distilling Industry 4. Waste Treatment

Products of Microbial Activity Having Commercial Importance: 1. Antibiotics –  Antibiotics –  Penicillin;  Penicillin; Streptomycin, Tetracyclines 2. Organic Solvents –  Solvents –  ethanol,  ethanol, butanol, acetone 3. Gases –  Gases –  CO  CO2, H2, CH4 4. Beverages –  Beverages –  wine,  wine, beer, distilled spirits 5. Foods –  Foods –  cheese,  cheese, fermented milk, soy sauce, vinegar, citric acid, yeast 6. Flavoring Agents –  Agents –  Monosodium  Monosodium Glutamate, soy sauce, Nucleotides 7. Organic Acids –  Acids –  lactic  lactic acid, acetic acid, butyric acid, propionic acid, citric acid 8. Glycerol 9. Amino Acids –  Acids –  lysine,  lysine, alanine 10. Steroids 11. Food and Feed Yeast –  Yeast  – Baker’s Baker’s Yeast, Brewer’s Yeast, Fodder’s Yeast 12. Legume Inoculant 13. Bacterial Insecticides 14. Vitamins –  Vitamins –  Vit.  Vit. B12, Riboflavin, Vit. A, gibberilline 15. Enzymes –  Enzymes –  amylase  amylase , protease, pectinase, invertae

Cell and Its Parts 363

cytoplasm mitochondria nucleus nucleolus nuclear membrane cell membrane

Chromosome (chromatin) 1.

2. 3. 4. 5. 6. 7.

Cell membrane  –   composed of proteins and lipids serve as a barrier from the external environment. It is semipermeable and selectively permit passage of substance into the cell while allowing exit of waste. Cytoplasm –  contain other organelles and the nucleus  Nucleus –  regulate metabolic and reproductive activity Mitochondria –  contain the respiratory system. Chloroplasts –  mitochondria of photosynthetic organism. Golgi bodies –  transport materials of cellular product. Cell wall –  protective substance of the cell.

Characteristics of Biological Material Microorganism are chemically very similar to higher animal cells and they can perform many of the same biochemical reactions. Generally, microorganism exists as single cell. There are four groups of organism which a biochemical engine is interested namely: a. Bacteria  b. Fungi including yeasts and actinomycetes c. Protozoa including algae d. Viruses including bacteriophage The characteristics of biological material could be summarized: 1.

Bacteria contain 50-60% protein, yeast 40-50% and mold 20%, most of which in enzymic. Some specie have a high lipid (or carbohydrate) content but generally, this is less than 10%. Viruses contain up to 50% nucleic acid, bacteria 20%, yeast 10% and mold 3%.

2.

Viruses are obligate parasite and require a specific host cell for their multiplication, often killing the lost in the process. Bacteria are largely unicellular and haploid (one set of genes) with the nuclear material lying free in the cytoplasm. They multiply by simple fission, through a primitive mating system had been found in the enteric 364

 bacteria. Fungi are multicellular with many migrating nuclei. They multiply by apical extension of the hythal filaments may produce both sexual and a sexual spores. Yeast, however grow by budding from single ovoid cell. 3.

The microbial cell genetic properties are preserved in their DNA. Four nucleotive (NMP, TMP, CMP, GMP) are polymerized in two strands bonded to each other to form a double nelix. The base are arranged such that adenine in one strand in complementary to thiamin in the other, while guanine is complementary to cytosine. When the DNA replicates, the order of bases in DNA is conserved by the two strands separating, each acting as template, while nucleotive complementary to those existing strand are polymerized to those existing strand are polymerized to form two doublestranded molecules identical with the original one. Errors may occur in the copying  process which give rise to mutant.

4.

When protein is required by a cell, the information for its synthesis is transcribed from one strand of the DNA into m-RNA; the order of bases in DNA code for the order of  bases in m-RNA. The m-RNA associated with ribosomes (non specific, relatively stable organelles) where the protein in synthesized. The amino acid are activated and associate with a specie of t-RNA. The t-RNA has a triplet base (anticodon) which is complementary to the triplet of bases (codon) in m-RNA specifying the particular amino acid.

5.

Each amino acid is specified by at least one codon but may have as many as six at the ribosome, amino acids are polymerized into protein in the order specified by m-RNA; the growing polypeptide is attached to the ribosome until the last amino acid is added, when the ribosome is free to combine with new m-RNA. Free of ribosome, m-RNA is hydrolyzed and its component nucleotive enters the nucleotive pool for resynthesis.

CELL HIERARCHY –  Order of molecular organization of cell

CO2  H 2O  N 2

Ribase Carbamyl  phosphate

Mono-nucleotides

alpha-keto acids

Simple sugars

 

Nucleic Acids

Proteins

PhosphoPyruvato Malate

Simple sugars

Polysaccharides

Acetate Malonate

Fatty Acid Glycerol

Lipids

Precursors (MW = 18-44)

Cell

Intermediates (MW = 50-250)

Organwelles

Enzymes Complexes Ribosomes Contracile systems

Building Blocks (MW = 100-350)

Supramolecular  Assemblies (Particle WT. = 10 6-109)

365

 Nucleus Mitochondria Chloroplasts

Macromole-Cells (MW = 103-109)

CELL

HAECKEL THEORY –  division in the living world A. Plant kingdom –  Flora B. Animal kingdom –  Fauna C. Microorganism –  Protist 1. Higher Protist or Eucaryotes 2. Lower Protist or Procaryoutes Cellular Organisms (3 types) 1. Unicellular 2. Multicellular 3. Coenocytic Chemical Make-Up of Bacterial Cells: 1. Proteins –  made up of amino acids joined by peptide linkage 2. Lipids or Fats  –   made up of fatty acids; water insoluble components of the cells that can be extracted by nonpolar solvents. 3. Carbohydrates –  polyhydroxy aldehayde or ketone 4.  Nucleotides –   monomeric units of nucleic acid macromolecules third  – OH of one nucleotide and fifth –  OH of another nucleotide Cultivation: 1. Chemical conditions 2. Temperature 3. Gas requirement 4.  pH 5. Other factors Isolation: 1. Pour Plate –   suspension of cell is mixed with the melted agar at 45°C and poured into a petri dish. When agar solidifies, cells are immobilized in the agar and grow into colonies. 2. Streak Place  –   the sterile, melted and cooled medium is first poured into a sterile  petri dish and allowed to harden thoroughly; then the surface of the hardened agar is inoculated by streaking the needle of swab across it. Bacterial Culture System A. Batch Culture  –   growth curve characterized by the lag phase, exponential phase, stationary phase and decline phase. Lag Phase  –   physiological adjustment of the organism to the environment following inoculation. Logarithmic or Exponential Phase  –   exhibits a constant rate of growth where the rate of increase of cells can be expressed as: dx

 Ux

dt 

U = growth x = microbial concentration t = time 366

Stationary Phase  –   growth ceases completely due to the exhaustion of nutrients, accumulation of waste products, change in pH. Decline Phase –  irreversible loss of ability to regenerate or reproduce. B. Continuous Culture  –   utilizes the bacterial kinetics of the exponential phase. This demands a continuous flow-in of the nutrients of growth and the corresponding outflow of the products of the culture. Sterilization: 1. Chemical 2. Mechanical 3. Thermal 4. Radiation 5. Energy Yielding Metabolism : Metabolism of carbohydrates, e.g. glucose. A. Anaerobic Fermentation 1. Glycolysis or EMP Pathway 2. Alcoholic Fermentation B. Aerobic Respiration – TCA (Tricarboxylic Acid Cycle) or Kreb’s Cycle ENZYMES A. Sources –  plant, animal organs, microbial cells B. Types: 1. Endo enzyme or Intracellular enzyme 2. Exo enzyme or Extracellular enzyme C. Enzyme Theories: 1. Lock and key theory (Emil Fischer) illustrates the precise fit between enzyme and substrate. 2. Induced Fit Theory (Koshland) Enzyme undergoes structural or conformational changes brought about or induced by the substrate. 3. Michaelis- Menten Theory –  Enzyme activity depends on substrate concentration. Equation: V 

   Km  S  Vm  x S 



V  Vm S  Km

= Velocity of enzymatic reaction = limiting (maximum) velocity = substance concentration = Michaelis –  Menten constant

EMP Pathway Glucose ATP ADP Glucose-6-Phosphate

367

Fructose-6-Phosphate ATP ADP Fructose-1,6-Diphosphate

Clyceraldehyde-3-Phosphate

Dihydroxyacetone Phosphate

1, 3-Diphosphoglyceric Acid 2 ADP 2 ATP 3-Phosphoglyceric Acid

2-Phosphoglyceric Acid

Phospoenolpyruvic Acid 2 ADP 2 ATP Pyruvic Acid 2 NADH 2 NAD Lactic Acid

TCA or Kreb’s Cycle

368

Proteins

Carbohydrate

Lipid

Amino Acids

Pyruvate

Fatty acids CO2

2H

Acetyl Co-A

Oxaloacetate

Citrate CO2

Malate

Cis-Atconitate

Fumarate

Isocitrate Succinate Ketoglutarate

2H

2H

2H

2H

Electron Transport and Oxidative Phosphorylation

ATP

General Properties of Enzymes: 1. Enzymes are proteins 2. Enzymes have electrical charges which depends on the pH and two pK values 3. Enzymes have definite three dimensional structures a.  primary structure  –   amino acid sequence of the polypeptide chain (most important and specific structure; determines secondary and tertiary structures)  b. secondary structure  –   spatial arrangement of polypeptide chains into helices,  pleated sheet and random coil structures. c. tertiary structure –  three dimensional arrangement of helices, pleated sheet d. and random coil structures in enzyme. e.

quaternary structure –  aggregation of enzyme submits or molecules into multi submit or multi enzyme complexes.

 Non-covalent bonds that contribute to the three dimensional structure of enzymes: 369

1. Hydrogen bond –  Interpeptide Hydrogen Bond; Side Group Hydrogen Bond. 2. Ionic Bond –  (electrostatic attraction) 3.  Non-polar Side Chain Interaction (Hydrophobic Bond) 4. Polar Side Chain Interaction 5. Enzymes are efficient catalysts and catalyze a wide range of chemical reactions. Six General Classes of Enzymes and Functions: 1. 2. 3.

4. 5. 6.

Oxido-reductases  –   oxidize or reduce substrates by transferring hydrogen or electrons Transferases –  remove groups (excluding hydrogen) and transfer them to acceptor molecules (excluding water); transfer of groups. Hydrolases –   for hydrolytic reactions. It catalyze the splitting of a covalent bond of the substrate and that of a water molecule with the subsequent addition of the hydrogen and hydroxide to the two fragments of the substrate molecule. Lyases  –   remove groups from the substrate after than by hydrolysis to form a double bond or conversely, add groups to the double bonds. Isomerases –  catalytic isomerizations. It causes isomerization to the substrate. Ligases or Synthetases  –   cause condensation of two molecules by splitting a  phosphate bond.

Enzyme Nomenclature: Based on their source Papais –  papaya Bromelin –  pineapple Pepsin –  stomach A. Based on the substrate used Urease –  urea Protease –  protein Cellulase –  cellulose Sucrase –  sucrose B. Based on their function Lysozyme –  to loosen Catalase –  catalyst Oxidase –  oxidation C. Systematic method Substrate –  nature of reaction 1. glucose –  oxidase 2. glycerol ester –  hydrolase

Definition of Terms:

Aerobe –  An organism that grow in the presence of air or O 2. Amino Acid –  A sub-unit of the protein structure.

370

Anaerobe –  An organism that grow in the absence of oxygen. Autolysis –  dissolution of the cells by self-produced lytic enzyme. Autotrophs –  organism that grow or uses CO 2 as its principal carbon source. Auxotrophs  –   nutritional mutant which require one or more nutrients in addition to those required by its wild type. Bacteriacidal –  an agent that kills bacteria. Bacteriostatic –   an agent that inhibits the bacterial growth by its presence without causing death. Binary fission –  cell division where the mother cell split into daughter cells. Biomass –  cellular mass e.g. bacterial cell or fungal mass. Biosynthesis  –   a change occurring within the bacterial cell such as the building up of  protein, carbohydrates from simple cell. Broth  –   a liquid medium wherein an active growth of microorganism is in progress; fermentation liquor wherein the process of fermentation is in progress. Beer –  fermentation liquor wherein fermentation process had just terminated. Enzyme  –   an organic catalyst produced by the cell. Constitutive  –   always present in the cell; substrate independent; induced  –   present in the cell only when needed, substrate dependent; extracellular (exo enzyme)  –   activity is outside the cell; digestive or hydrolytic in its activity. Intracellular (endoenzyme) activity is inside the cell usually involved in the  bio-synthesis of macromolecules and energy-yielding reactions. Facultative  –   having the characteristics that permit alternate responses under different conditions; e.g. facultative anaerobe can grow aerobically. Fermentation  –   process in which chemical changes are brought about in an organic substance through the action of enzyme elaborated by microorganism. Generation time –  the time required for a mother cell to divide into two daughter cells. Inoculant –  starting microbial culture in fermentation process. Heterotroph  –   an organism that uses predominantly organic carbon for energy and  photoplasmic building block. Lag phase –  early period of growth where the organism adjust to its new environment. Logarithmic growth  –   phase in the microbial life cycle when the cells are dividing exponentially. Mesophile –  an organism that grow optimally at 20°C to 37°C 371

Microbial  –   something of the organism; from the word microbe which means microorganism. Microaerophile  –   an organism that prefers to grow under reduced oxygen tension but sometimes increased carbon dioxide tension. Mutation –  a chemical change in the genetic code of the cell Mycelium –   a mass of hyphae of a mold or actinomycetes colony. Obligate –  strict or restricted; e.g. obligate aerobe can grow only in the presence of oxygen; obligate thermophile can grow only at elevated temperatures in relation to others. Phage –  a bacterial virus Photoplast –  that part of t he cell which includes the cell membrane and its content. Phototroph –  an organism exhibiting wild type nutrition. Putrefaction –  decomposition of protein under anaerobic conditions. Respiration  –   oxidation of the chemical compound by the organism coupled with the released of energy; Aerobic-final oxygen acceptor is an inorganic substance like SO 3, NO 3 other than molecular oxygen. Strain –  a classification of specie of an organism identifying is a part from the rest by virtue of specificity of source. Substrate –  nutrient for cellular growth. Thermophile –  an organism that grow optimally above 45°C. Viable –  state of the living cell where it is still capable of division. D N A –  deoxyribonucleic acid –  holder of the genetic information of the cell. R N A –  ribonucleic acid –  responsible for the coding and the transfer of genetic information. SCP  –   single cell protein  –   protein obtained for the growth or culture of unicellular microorganism. Cultivation  –   process of propagating organism by providing the proper environmental condition such as nutrient, temperature and PA. Isolation –  separation of a particular microorganism from the mixed population that exist in nature. Psychrophile –  organism whose optimum temperature for growth is 10°C.

372

Inoculum –  serum containing microorganism. Some useful utilization of microorganisms are the following: 1. Food Processing: soy sauce –  aspergillus sojae vinegar –  acetobacter nata –  acetobacter xylinum  pickles –  lactic acid bacteria milk products like cheese and sour cream tempe –  soybean –  rhizopus oligosporus ontjom –  peanut cake –  neurospora sitophilia 2. Alcoholic Beverages wine, beer, sake, tapuy, basi, whisky, rum, lambanog 3. Fuel Alcohol –  saccharomyces cerevisial xymomones mobilis  biogas –  mixture of microorganisms methane –  producing bacteria 4. Production of: (a) antibiotics  penicillin –  penicillium chrysogenum streptomycin –  streptomyces griseus tetracyclines –  streptomyces aureofaciens  polymixins –  bacillus polymyxa (b) amino acids glutamic acid –  corynabacterium glutamicum (c) vitamins B-carotene –  choanspore conjuncta Blakaslea trispora riboflavin –  ashbye gossypti Enemothecium ashbili Vitamin B12 (d) hormones Gibberallins –  Gibberella fugikunol

REVIEW QUESTIONS AND PROBLEMS 1.

Enzymes are a. proteins that catalyzes chemical reactions, but they do not have the usual chemical and physical properties or proteins  b. proteins containing a high concentration of D-amino acids c. proteins and may be consider ed as such chemically and physically d. compounds of amino acids, but they cannot be hydrolyzed to form free amino acids

2.

The mechanism of enzymatic action involves a. slow degradation of the enzyme to form an enzyme-substrate complex  b. temporary union of enzyme with substrate 373

c. resistance to deactivation by high temperature d. rapid degradation of the enzyme to form an enzyme-substrate complex 3.

Factor(s) that influence(s) enzymatic activity is (are) a. temperature c. concentration, substrate and cofactors  b. pH d. all of the above

4.

The process of fermentation can be considered to be a. oxidation c. aerobic respiration  b. dehydration d. anaerobic respiration

5.

A study was made to evaluate the constants so that the Michaelis-Menten relationship could be used to describe waste utilization by bacteria. It was found that one gram of  bacteria could decompose the waste at a maximum rate of 20 grams per day when the waste concentration was high. Also, it was found that this same quantity of bacteria would decompose waste at a rate of 10 grams/day when the waste concentration surrounding the bacteria was 15 mg/l. The rate of waste decomposition by 2 grams of  bacteria if the waste concentration were maintained at 5 mg/l is a. 10 g/day b. 20 g/day c. 5 g/day d. 15 g/day

6.

Bacteria which converts alcoholic solution to vinegar are a. coli b. acetobacters c. bacilli

d. proteins

7.

The biological decomposition of organic matter accompanied by the production of foul smelling products in an anaerobic condition is a. pollution b. putrefaction c. dissolution d. stabilization

8.

A waste treatment process by which biologically active growths are continuously circulated with incoming biodegradable waste in the presence of oxygen is a. activated sludge process c. agitation process  b. stabilization process d. trickling filter process

9.

Materials in which microorganism are grown in a laboratory are a. nutrients b. substrates c. enzymes d. culture media

10. Group of microorganisms that grow in the presence of low oxygen concentration are a. pathogens b. bacteria c. fungi d. microaerophiles 11. The rate of microbial growth is temperature-dependent. Bacteria which grow over the temperature range of 30°C to 40°C are called a. psychrophiles c. mesophiles  b. hydrophiles d. thermophiles 12. There are several forms suggested by which the hyperbolic Michaelis Menten equation may be expressed linearly. If the substrate concentration, S is plotted against reaction velocity, V; a linear plot is obtained. The equation is called a. Lineweaver and Burke equation  b. Eadie-Hofstee equation c. Hanes-Woolf equation d. Eisentahl and Cornish Bowden equation 374

13. The enzymatic hydrolysis of an ester occurs according to the following reactions: O O enzymes R-C + H2 O   + ROH  R-C OR OH O The following data on the rate of formation of R-C at 25°C and pH = 6.5 were obtained: H Substrate concentration, O Millimoles R-C per liter OR Reaction velocity , O Millimoles R-C per li-sec OH

2.5

5

10

0.024

0.036

0.053

15

0.06

20

0.064

The Michaelis constant, km in millimoles per liter is a. 6.39 b. 9.36 c. 3.69 d. 5.19 Problems 14 and 15 are based on the following information A continuously stirred tank reactor (CSTR) with a working volume of 5,000 liters is used for the production of baker’s yeast. The instantaneous concentration of the biomass in the vessel is 42.45 g/l. The overall reaction for aerobic fermentation is expressed as: 0.556 C6 H12 O6  + 0.301 NH3 + 1.43 O2 0.301 C6H10O3 N + 2.283 H2O + 1.532 CO2 The empirical formula for the biomass is C 6H10O3 N and molasses contains 51.2% glucose. 14. The specific growth rate of the yeast in order to maintain a daily production of one ton is a. 0.5628/day b. 0.2865/day c. 0.8265/day d. 0.6825/day 15. The daily molasses consumption if the residual sugar in the outgoing broth is 0.5% glucose (weight/volume) is a. 4133 1/day b. 3143 1/day c. 3314 1/day d. 3413 1/day 16. It is desired to reduce the bacterial count of polluted water from 8 million organisms  per ml to 17 organisms per ml. The number of completely mixed chlorine contact chambers in series, each having a detention time of 40 minutes, that would be required if the first order removal rate constant is 8 per hour is a. 5 vessels b. 7 vessels c. 10 vessels d. 8 vessels 17. Given a specie of a microorganism that doubles every 2.5 hours, the mass of biomass that may be expected from 500 liters of seed if each liter contains 5 grams biomass and the fermentation culture was maintained for 12 hours is a. 63 kg b. 55 kg c. 85 kg d. 70 kg 18. The Philippine Cornstarch Corporation prepares pharmaceutical glucose from cornstarch by enzyme hydrolysis. It was observed that when the starch concentration 375

of the slurry was 5%, the rate of conversion of starch to glucose was 0.04 kg per second. When the starch concentration was made 10%, the turnover rate was 0.07 kg  per second. The maximum production level of glucose that can reasonably be attained  per shift of 8 hours is a. 6084 kg b. 8064 kg c. 1008 kg d. 0.28 kg 19. In a 1,000 liter vessel operating at 80% capacity, it takes 10 minutes to reduce the vegetative cell population by one fifth and 20 minutes to reduce the spore population 3  by the same ratio. If the spore population is ini tially 1 x 10  per cc and vegetative cells 4 were 1.5 x 10  per cc, the efficiency of sterilization if such were carried for 30 minutes is a. 52.5% b. 57.4% c. 74.5% d. 47.5% 20. A water solution of molasses contains 10% by weight sucrose (C 12H22O11). The CO2 formed in the reaction can be considered as having a negligible solubility in the solution and 10% of the sugar can be assumed as unchanged. The weight percent of ethyl alcohol in the solution after 90% of the sucrose has been converted to ethyl alcohol by fermentation is a. 5.1% b. 1.5% c. 4.6% d. 6.5% Problems 21 and 22 are based on the following information Albizzia Falcataria, a specie, of plywood, after an initial thermochemical hydrolysis yielded 25% maltose, 3% sucrose, 12% cellibiose, 43% oligosaccharides and 17% non carbohydrates residues. The resulting hydrolyzate is passed through a column of immobilized enzyme systems so that all types of dissacharides are converted further to hexone units. In alcohol fermentation, the rule of thumb is 10% of the substrate is converted to  biomass and 90% to alcohol.

21. If one metric ton of pulpwood is processed daily, the mass of glucose that may be expected to be produced per six-day week is a. 2,500 kg b. 2,526 kg c. 2,256 kg d. 5,262 kg 22. If the resulting hydrolyzate were fermented to ethanol, the mass of refined alcohol that may be expected to be recovered if distillation efficiency is 95% is a. 1,200 kg b. 1,162 kg c. 1,223 kg d. 1,322 kg 23. One metric ton of wild potatoes were hydrolyzed enzymically and the hydrolyzate contained the following: maltose = 15% xylose = 3% glucose = 18% oligosaccharides = 34%  pentose = 3% others = 27% It was observed that of the hydrolyzate, only maltose and glucose were fermentable by alcohol yeast. Assuming 5% of the fermentables were used for the maintenance and growth of the organism, the mass of alcohol that can theoretically be expected from the hydrolyzate is a. 173 kg b. 158 kg c. 338 kg d. 127 kg 376

24. The nutrient for cellular growth is called a. protein b. substrate c. carbohydrate

d. lipid

25. This is the early period of growth where the organism adjust to its new environment a. stationary phase c. lag phase  b. logarithmic phase d. decline phase 26. Genetic information is stored in the structure of the DNA molecule. Which of the following obtains the code for protein synthesis from DNA and served as the template for peptide formation a. transfer RNA c. ribosomal RNA  b. messenger RNA d. colon 27. a. Endoenzymes b. Exoenzymes c. Isoenzymes d. Allosteric enzymes are those that exhibit sigmoidal curves when activity is plotted against substrate concentration 28. The isoelectric point of isolcucine (2.36, 9.68) is: a. 6.02 b. 6.06 c. 5.98

d. 5.97

29. Hydrolysis of one mole of sucrose gives a. 1 mole of glucose and 1 mole of galactose  b. 1 mole of glucose and 1 mole of fructose c. 2 moles of glucose d. 1 mole of mannose and 1 mole of glucose

30. Denaturation of protein a. involves conformational changes in the structure without hydrolysis of peptide  bonds  b. involves changes in the secondary, tertiary and quarternary structures of the protein molecules c. is often an irreversible process d. all of the above 31. a. Glycolysis b. Alcoholic Fermentation c. Methane Fermentation d. Kreb’s Cycle is the aerobic metabolism of the carbohydrates 32. Proteins that act as catalyst in biochemical reactions involving living organisms are: a. amino acids b. enzymes c. inhibitors d. polysaccharides 33. If the BOD = 300 mg/l for a 1 mgd (million gallon daily) sewage plant, determine the number of pounds of organic load present in the water per day. a. 2600 lbs/day b. 2501 lbs/day c. 3000 lbs/day d. 5000 lbs/day 34. a. Lyophitization b. Pasteurisation c. Fermentation is the method used to free milk from disease germs

377

d. Putrefaction

35. a. Nucleus b. Mitochondria is the power house of the cell

c. Lysosone

d. Cytoplasm

36. a. SCP b. TDP c. TDT d. ATP is the temperature at which a microorganism is killed within a period of 10 minutes. 37. A visible concentrated growth of algae or other aquatic life/plants is called a. phytoplankton b. amoeba c. bloom d. zoo-plankton 38. In treating 25 million gallons of water daily, 167 lbs. of liquid chlorine are applied, what is the dosage in mg/l? a. 0.801 mg/l c. 1.2 mg/l  b. 0.502 mg/l d. 0.608 mg/l 39. Which of the following organisms is considered coenocytic? a. protozoa b. algae c. molds d. fungi 40. Production of ethanol fr om cassava and banana peels involves: a. fermentation c. hydrolysis  b. enzymatic action d. all of the above 41. The microorganism utilized in the production of pickles is: a. acetobacter c. streptomyces griseus  b. lactic acid bacteria d. aspergillus sojae

42. a. Algae b. Amoeba c. Slime Molds are multicellular seaweeds.

d. Yeast

43. a. Zoology b. Biochemistry c. Botany d. Microbiology is the study of living organisms too small to be seen clearly by the naked eyes. 44. The color of fruit like papaya is attributed to a pigment which is a precursor of Vitamin A. This substance is a. Lecithin b. carotene c. lipoprotein d. ribotlavin 45. The citric acid cycle is considered an aerobic pathway because: a. oxygen is a substrate in some of the cycle reactions  b. the reduced cofactors are all oxidized through the electron transport chain c. The cycle enzymes are all oxidative by nature d. Water is a product of the cycle 46. _______ is the enzyme in the stomach. a. urease b. papase

c. pepsin

47. The organism that reproduce by sparulation is a. bacteria b. molds c. protozoa

d. bromelis

d. yeast

48. _______ is the organism that grow or uses CO 2 as its principal carbon source. 378

a. autotroph

b. aerobe

49. A basic amino acid is a. alamine b. lysine

c. mesophile

d. heterotroph

c. serine

d. cystein

50. _______ is a continuous system cultivator. a. chemostat b. sterilizer c. scrubber

379

d. precipitator