metabolism part a background 1. a. metabolism refers to all the chemical reactions which occur in...

METABOLISM part A BACKGROUND 1

A. METABOLISM refers to all the chemical reactions which occur in life. These reactions are: 1.CATABOLIC - degradative reactions which: a.Convert food into twelve, key, low molecular weight intermediates (which can be converted in anabolic reactions into low molecular weight precursors of proteins, polysaccharides, lipids, and polynucleotides). b.Oxidize food, generating NADH + H+, which transfers electrons to the electron transport chain, with resulting ATP generation. c.Convert food into low molecular weight compounds which can serve to generate ATP by substrate level phosphorylation. 2.ANABOLIC - biosynthetic reactions which generate amino acids, fatty acids, monosaccharides, and mononucleotides and polymerize them into proteins, lipids, polysaccharides, and polynucleotides. B.PATHWAYS. Sets of reactions in which the product of one reaction serves as the substrate for the next reaction are called PATHWAYS. For example, compound A might be converted into compound E by four, successive reactions. C.ENZYMES are necessary to catalyze most biochemical reactions so that the reaction reaches equilibrium within a time scale useful for life. Enzymes usually are proteins; they usually catalyze one, specific reaction; usually every reaction requires catalysis by one specific enzyme. Although a given reaction, such as A + B = C + D, might come to equilibrium, in the test tube, with only slightly more C + D formed than the amount of A + B remaining, in living organisms, this reaction usually goes to completion. This is possible because C or D is removed by, for example, conversion to some other product -if C or D is not removed, the reaction comes to equilibrium. D. GLYCOLYSIS is the oxidation/conversion of glucose to pyruvate (also called the Embden-Meyerhoff Pathway): NAD+ is converted into NADH+ H+ ATP is generated by substrate level phosphorylation E.RESPIRATION converts pyruvate to CO 2 (Krebs cycle, citric acid cycle, Tricarboxylic acid cycle) and in the process: NADH + H+ are formed, FAD is converted into FADH2, GDP is converted into GTP. The reducing compound pool reduces the electron transport chain, generating a pH gradient across the Cytoplasmic membrane, the resulting proton motive force is used by ATP synthase to convert ADP + Pi into ATP (Oxidative Phosphorylation) A terminal electron acceptor is required to accept electrons from the electron transport chain. In aerobic respiration O 2 accepts electrons and is converted to H 2 O. F.FERMENTATION is a process by which glucose oxidation (glycolysis) can+ be sustained in the absence of a terminal electron acceptor. That is the oxidation/reduction reactions are internally balanced. Pyruvate is reduced to lactate or ethanol by NADH H+, regenerating NAD+. G.Microbes have evolved to occupy many niches. Four modes of respiration include aerobic, anaerobic, chemolithotrophic, and photosynthetic. 2

OVERVIEW - ANABOLISM, CATABOLISM ENERGY Free Energy Change, Exergonic, Endergonic ENZYMESEnzymes - Catalysts, Lower Activation Energy Bind substrates Strain specific bonds in substrates; help form bonds COENZMES Low molecular weight compounds, Function with enzymes Apoenzyme plus coenzyme = holoenzyme OXIDATION/REDUCTION REACTIONS - REDOX Oxidation - loss of electron - electron donor Reduction - gain of electron - electron acceptor Coupled Oxidation/Reduction reactions ELECTRON CARRIERS Nicotinamide adenine dinucleotide [NAD] - coenzyme involved in oxidation/reduction NAD+ plus 2e- plus 2H+ NADH plus H+ OxidizedReduced [Reducing Power] HIGH AND LOW ENERGY BONDS Esters - low energy glucose-6-phosphate Anhydrides -high energy ATP, adenosine triphosphate - Universal source of high energy 1,3-diphospho glyceric acid - (1,3-diphospho glycerate) 3

CARBON/ENERGY GLUCOSE BYPRODUCTS H 2 O; CO 2 CHEMICAL SYNTHESIS; FOOD TRANSPORT [MOTILITY] G-6-PO 4 ATP LOW MOLECULAR WEIGHT BUILDING BLOCKS MACROMOLECULES AMINO ACIDS FATTY ACIDS MONOSACCHARIDES MONONUCLEOTIDES PROTEINS-ENZYMES; FLAGELLIN; RIBOSOMES ETC. PHOSPHOLIPIDS POLYSACCHARIDE [PEPTIDOGLYCAN] DNA/RNA [t,r,m] 4

G -FREE ENERGY - ENERGY RELEASED IN FORM ABLE TO DO WORK G' CHANGE IN FREE ENERGY UNDER STANDARD CONDITIONS AND pH NEGATIVE G - EXERGONIC FREE ENERGY RELEASED REACTION OCCURS SPONTANEOUSLY EQUILIBRIUM FAVORS RIGHT A + B C + D LARGE - G SMALL- G 5

POSITIVE G - ENDERGONIC FREE ENERGY REQUIRED REACTION WILL NOT OCCUR SPONTANEOUSLY EQUILIBRIUM FAVORS LEFT G VALUE -DOES NOT PREDICT HOW LONG WILL BE REQUIRED TO REACH EQUILIBRIUM 1 / 2 O 2 + H 2 H 2 O G = -237 kj/mole [4.2 KILOJOULES = 1 KILOCALORIE] 6

G GG NO ENZYME PLUS ENZYME ACTIVATION ENERGY + ENZYME NO ENZYME SUBSTRATEPRODUCT ENZYMES 10 8 - 10 20 x RATE 1. BIND SUBSTRATE(S) 2. HOLD SUBSTRATE IN ENZYME CATALYTIC SITE- STRAIN BONDS OR HELP FORM BONDS 3. REDUCE ACTIVATION ENERGY ENZYME DOES NOT CHANGE: FREE ENERGY OF SUBSTRATE/PRODUCT EQUILIBRIUM; G IS THE SAME +/- ENZYME (Not a time scale) 7

ENZYME - TURN OVER NUMBER - NUMBER OF MOLECULES OF REACTANT (SUBSTRATE) CONVERTED TO PRODUCT PER MOLECULE OF ENZYME PER UNIT OF TIME (e.g., SECOND) TYPICAL: 2,000 / SECOND = 120,000 / MINUTE 8

ENZYME - ALDOLASE ENZYME - SUBSTRATE COMPLEX + + FRUCTOSE-1,6- BISPHOSPHATE DI-HYDROXY ACETONE PHOSPHATE GLYCERALDEHYDE -3-PHOSPHATE ALDOLASE 359 a.a.; MW = 39,147 + APPRECIATE ! 9

ENZYME - ALDOLASE ENZYME - SUBSTRATE COMPLEX + + FRUCTOSE-1,6- BISPHOSPHATE DI-HYDROXY ACETONE PHOSPHATE GLYCERALDEHYDE -3-PHOSPHATE ALDOLASE 359 a.a.; MW = 39,147 + ALDOLASE SPLITS HERE BREAKS TWO BONDS FORMS TWO MOLECULES APPRECIATE !10

OXIDATION - LOSS OF ELECTRON REDUCTION - GAIN OF ELECTRON H 2 + 1 / 2 O 2 H 2 O H 2 - ELECTRON DONOR H 2 2e - + 2H + 1 / 2 O 2 - ELECTRON ACCEPTOR 1 / 2 O 2 + 2e - O - - NET CHANGE : 2H + + O - - H 2 O REDUCING AGENT OXIDIZING AGENT H 2 - REDUCING AGENT - DONATES ELECTRONS - BECOMES OXIDIZED 1/2 O 2 - OXIDIZING AGENT - ACCEPTS ELECTRONS - BECOMES REDUCED SUMMARY: 11

COENZYMES LOW MOLECULAR WEIGHT, NON-PROTEIN MOLECULES WHICH PARTICIPATE WITH ENZYMES IN METABOLIC REACTIONS. ESSENTIAL FOR THOSE REACTIONS. LESS SPECIFICITY THAN ENZYMES. RECYCLE. 12

NICOTINAMIDE ADENINE DINUCLEOTIDE NAD + 2e + 2H NADH + H OXIDIZED STATE; OXIDIZES FOOD PICKS UP 2e - and 2H + FROM FOOD; REDUCING AGENT IS REDUCED REDUCED STATE NADH + H NAD + 2e + 2H TRANSFERS e - TO OTHER E.T.C. TO GENERATE ATP IS OXIDIZED REDUCED STATE; REDUCES ELECTRON TRANSPORT CHAIN OXIDIZED STATE 13

+2e +2H REDUCED OXIDIZED +H NAD + NADH + H + NICOTINAMIDE ADENINE DINUCLEOTIDE APPRECIATE ! 14

HIGH AND LOW ENERGY BONDS FOOD OXIDATION MAIN EVENT - ENERGIZES THE CYTOPLASMIC MEMBRANE; PERMITS FORMATION OF HIGH ENERGY BONDS - ANHYDRIDES HYDROLYSIS OF HIGH ENERGY BONDS RELEASES LOTS OF ENERGY WHICH CAN BE USED TO DRIVE WORK: ANABOLISM (CHEMICAL SYNTHESIS) FOOD TRANSPORT 15

-D-GLUCOSE-6-PHOSPHATE ESTER LOW ENERGY 1,3 DIPHOSPHO GLYCERIC ACID ANHYDRIDE HIGH ENERGY ADENOSINE TRIPHOSPHATE ANHYDRIDE HIGH ENERGY 16

METABOLISM B - ENERGY FROM FOOD OXIDATION GLYCOLYSIS - glucose conversion to pyruvate [Embden-Meyerhoff Pathway] NADH plus H+ generated Substrate level phosphorylation RESPIRATION -pyruvate conversion to carbon dioxide plus water [in aerobic respiration] Tricarboxylic acid cycle generates NADH plus H+, FADH2, GTP Flow of electrons to Electron Transport Chain ELECTRON TRANSPORT CHAIN (SYSTEM) ENERGIZED MEMBRANE CHEMIOSMOSIS PROTON MOTIVE FORCE pH Gradient; H+ and OH- ATP Synthase - Oxidative Phosphorylation Terminal Electron Acceptor (Oxygen in aerobic respiration) REDUCTION; DELTA E o ; DELTA G FERMENTATION - Pyruvate> Lactic Acid (lactate) Pyruvate> Ethanol plus CO 2 GLYCOLYSIS PLUS FERMENTATION: Allow glucose conversion to lactate or ethanol with internally balanced redox reactions. Do not require terminal electron acceptor. Result in only partial oxidation of glucose carbons. Yield only small amount of potential energy of glucose. Allow ATP generation by substrate level phosphorylation. Permit growth in absence of oxygen. 1

CITRIC ACID CYCLE NAD + NADH + H + FAD FADH 2 GDP GTP GLYCOLYSIS NAD + NADH + H + ADP ATP SUBSTRATE LEVEL PHOSPHORYLATION ELECTRON TRANSPORT CHAIN NADH + H + NAD + ADP ATP [OXIDATIVE PHOSPHORYLATION] 6O 2 6H 2 O TERMINAL ELECTRON ACCEPTOR GLUCOSE 2 PYRUVATES 6CO 2 RESPIRATION (AEROBIC) 2

FERMENTATION NOTE: NAD RECYCLES 2 LACTATES OR 2 ETHANOLS +2 CO 2 NADH + H + NAD + GLUCOSE NADH + H + NAD + PYRUVATE 3

SUBSTRATE LEVEL PHOSPHORYLATION OXIDATIVE PHOSPHORYLATION LOW MOLECULAR WEIGHT - PO 4 CONTAINING COMPOUND + ADP ATP (PLUS LOW MOLECULAR WEIGHT COMPOUND) NADH + H + TRANSFER ELECTRONS TO ELECTRON TRANSPORT CHAIN ELECTRON FLOW IS COUPLED TO ATP SYNTHESIS ADP + Pi ATP REQUIRES TERMINAL ELECTRON ACCEPTOR e.g., O 2 WAYS TO GENERATE ATP 4

PHOSPHO - ENOL PYRUVATE ENZYME - PYRUVATE KINASE PYRUVATE SUBSTRATE LEVEL PHOSPHORYLATION 5 APPRECIATE !!!

GLUCOSE GLUCOSE-6-PO 4 FRUCTOSE-6-PO 4 FRUCTOSE-1,6-BISPHOSPHATE CH 2 O PO 3 H 2 CH 2 OH C O HC O HC OH CH 2 O PO 3 H 2 45 DIHYDROXY ACETONE PHOSPHATE GLYCERALDEHYDE -3-PHOSPHATE GLYCOLYSIS ATP ADP 6

6 GLYCERALDEHYDE -3-PHOSPHATE GLYCOLYSIS ADP ATP H C O H C OH H C O PO 3 H 2 H C O P OH H C OH H C O PO 3 H 2 H OO OH C OH H C OH H C O PO 3 H 2 H O 1,3 BISPHOSPHO- GLYCERATE 3-PHOSPHO- GLYCERATE 7 Pi e-e- NAD + NADH + H + REDUCING POWER SUBSTRATE LEVEL PHOSPHORYLATION 7

GLYCOLYSIS ADP ATP 2-PHOSPHO GLYCERATE PHOSPHOENOL PYRUVATE 8 SUBSTRATE LEVEL PHOSPHORY- LATION C OH H C O PO 3 H 2 H C OH H O C O P C OH H C O H O CH 3 C OH C O O OH 10 9 PYRUVATE C O P OH OC OH HIGHER ENERGY THAN ANHYDRIDE OH 8

AEROBIC RESPIRATION PYRUVATE NADH + H + NAD + CoA CO 2 CoA CITRIC ACID (C 6 ) OXALO- ACETATE Q 9

ENERGY YIELD FROM PYRUVATE OXIDATION 1 PYRUVATE3 CO 2 1 NAD + 4 NADH & H + 12 ATP 1 FAD1 FADH 2 2 ATP 1 GDP + 1 Pi1 GTP 1 ATP 15 ATP EQUIVALENT TO 11 APPRECIATE !!!

ELECTRON TRANSPORT CHAIN (SYSTEM) 1.ACCEPTS e - FROM DONORS NADH & FADH 2 2.USES ENERGY RELEASED IN OXIDATION/ REDUCTION REACTIONS TO ENERGIZE MEMBRANE AND SYNTHESIZE ATP 1. NADH DEHYDROGENASES 2. FLAVO PROTEINS 3. IRON-SULFUR PROTEINS 4. QUINONES (NON - PROTEINS) 5. CYTOCHROMES RE-DOX ENZYMES 12

REDUCTION POTENTIAL E' O -0.4SUBSTRATES, AS GLYCERALDEHYDE-3-PHOSPHATE -0.3NADH, NADH DEHYDROGENASE -0.2FLAVOPROTEIN -0.1IRON SULFUR PROTEINS QUINONES 0 CYTOCHROMES +0.4NO 3 - NO 2 - +0.8OXYGEN O 2 ENERGY POOR 13 ENERGY RICH

CHEMIOSMOSIS - GENERATES PMF (PROTON MOTIVE FORCE) NDH = NADH DEHYDROGENASE pH GRADIENT; ENERGIZES CM; PMF GENERATED INSIDEOUTSIDE 14

H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ OH - ADP + Pi ATP ATP SYNTHASE ENERGIZED MEMBRANE - SYNTHESIZES ATP [ROTATES FLAGELLA] OUTSIDE THE MEMBRANE INSIDE THE MEMBRANE 15

ATP SYNTHASE TINIEST BIOMOLE- CULAR MOTOR IN WHOLE UNIVERSE 10NANO METERS 9-12 SUBUNITS ATOMIC FORCE MICROSCOPY CYTOPLASMIC MEMBRANE SHAFT CYTOPLASM

STATOR THE MOTOR ROTOR INCLUDES SHAFT PREVENT F1 SUBUNITS FROM ROTATING PROTON GRADIENT ALLOWS MOTOR TO ROTATE ROTOR WITH SHAFT ROTATING SHAFT CHANGES CONFORMATION OF F1 SUBUNITS CHANGES ALLOW: ADP + Pi TO ENTER; BIND BETA CATALYTIC SITE; ATP TO BE SYNTHESIZED; ATP TO BE RELEASED H+ TRANSPORTED INSIDE

ATP SYNTHASE ADP + Pi + H + ATP + H 2 O ANHYDRIDE 16

E o - REDUCTION POTENTIAL - TENDENCY TO DONATE ELECTRONS; i.e., TO OXIDIZE SOMETHING UNDER STANDARD CONDITIONS (I MOLAR) MEASURED IN VOLTS MUST BE MEASURED RELATIVE TO STANDARD STANDARD IS HYDROGEN: H + + e- > 1/2H 2 E o = 0 VOLTS (BY CONVENTION) CONSIDER: MATERIAL X + e- > X- WHAT IS REDUCTION POTENTIAL? CHAMBER ACHAMBER B X + e- > X- BRIDGE H + + e- > 1/2H 2 ELECTRONS FLOW TO H+, E o IS NEGATIVE X HAS LOWER AFFINITY FOR e- THAN H+ ELECTRONS FLOW TO X, E o IS POSITIVE X HAS HIGHER AFFINITY FOR e- THAN H+ VOLTMETER MEASURES VOLTAGE

E o BIOLOGY pH = 7.0 H+ + e- > 1/2H2 -0.42 NAD + + 2e- + 2H+ > NADH + H + -0.32 STRONG REDUCER 1/2O 2 + 2e- + 2H+ > H 2 0 +0.82 STRONG OXIDIZER

DELTA G OF REACTION DETERMINED BY DELTA E o OXIDANT + e- > REDUCTANT (a) 1/2O 2 + 2e- + 2H+ > H 2 0 +0.82 (b)NAD + + 2e- + 2H+ > NADH + H + -0.32 DELTA Eo = (a) - (b) = +0.82 - (-0.32) = 1.14 DELTA G = - n x F x DELTA E n = NUMBER OF e- [2 IN THIS EXAMPLE] F = FARADAY CONSTANT IN CALORIES 23.062 Kcal/volt.mol DELTA G IS NEGATIVE AND = - 53 Kcal/MOLE THIS PATHWAY IS EXERGONIC SUPPOSE FINAL ELECTRON ACCEPTOR IS NITRATE?

YIELD - GLYCOLYSIS + RESPIRATION GLYCOLYSIS 1 GLUCOSE2 PYRUVATES AEROBIC RESPIRATION 2 PYRUVATES + 6O 2 6CO 2 + 6H 2 O INPUT: 2ATPYIELD SUBSTRATE LEVEL PHOSPHORYLATION4 ATP 2 NADH ETC6 ATP 8 NADH24 ATP 2 FADH 2 4 ATP 2 GTP [EQUIVALENT]2 ATP GROSS40 ATP NET38 ATP 17 APPRECIATE !!

PROTON MOTIVE FORCE (ENERGIZED MEMBRANE) ADP + Pi ATP REDUCING POWER (FROM FOOD OXIDATION) LIGHT ENERGY (PHOTOSYNTHESIS) FLAGELLA ROTATION ACTIVE TRANSPORT (FOOD) 18

LACTIC ACID FERMENTATION CH 3 C OH C O O PYRUVATE CH 3 C OH H C OH O LACTATE REDUCED e-e- NADH + H + NAD + NET: GLUCOSE 2 LACTATE 2 ADP + 2 Pi 2 ATP 19

ETHANOL FERMENTATION NET: GLUCOSE 2CO 2 + 2 ETHANOL 2 ADP + 2 Pi 2 ATP CH 3 C OH C O O PYRUVATE REDUCED TO e-e- NADH + H + NAD + CH 3 H C O CH 3 H H C OH ACETALDEHYDE ETHANOL + CO 2 20

METABOLISM - PART C MODES OF NUTRITION AND RESPIRATION - BIODIVERSITY Aerobic respiration, Anaerobic respiration Chemolithotrophic metabolism Phototrophic metabolism NITROGEN FIXATION CATABOLISM ANABOLISM INTERACTIONS ANABOLISM - BIOSYNTHESIS Low Molecular Weight Building Blocks (Precursors of Macromolecules) Twelve key, central metabolites Pentoses Amino Acids - Alanine (from Pyruvate) Tryptophan (from Phosphoenolpyruvate and erythrose-4-phosphate) 1

MODE AEROBIC ANAEROBIC CHEMO- LITHOTROPHIC PHOTO- TROPHIC CARBON ORGANIC COMPOUNDS ANABOLISM ORGANIC COMPOUNDS CO 2 ALL ORGANIC COMPOUNDS ENERGY ORGANIC COMPOUNDS OXIDATION TO CO 2 ORGANIC COMPOUNDS H 2 H 2 S NH 3 LIGHT PROVIDES ENERGY ELECTRON ACCEPTOR O 2 H 2 O NO 3 - NO 2 - NO 2 - N 2 SO 4 - - SO 3 - - SO 3 - - H 2 S O 2 H 2 O NO TERMINAL e - ACCEPTOR e - FLOW IS CYCLIC FOOD NUTRITION AND RESPIRATION MODES 2

PHOTOTROPHIC NUTRITION AND RESPIRATION [PLANTS AND CYANOBACTERIA - OXYGENIC, EVOLVE OXYGEN FROM H 2 O] ANOXYGENIC PHOTOSYNTHETIC BACTERIA - DO NOT GENERATE O 2 - HAVE BACTERIOCHLOROPHYLL PROTON DONORS [H 2 S; SUCCINATE] PROTON GRADIENT- PROTON MOTIVE FORCE ATP SYNTHESIS EXCITED B Ch P BACTERIO- CHLOROPHYLL [B Ch P] LIGHT 3

NITROGEN FIXATION N 2 ATMOSPHERIC NH 3 AMMONIA ORGANIC NITROGEN RHIZOBIUM - LEGUMES AZOTOBACTER - FREE LIVING 4

ORGANIC COMPOUNDS (GLUCOSE) CATABOLISM BY-PRODUCTS (WASTE) ATP SIMPLE COMPOUNDS [12 KEY, CENTRAL METABOLITES] LOW MOLECULAR WEIGHT PRECURSORS OF MACROMOLECULES CELLULAR CONSTITUENTS ANABOLISM 5

GLUCOSE-6-PHOSPHATE FRUCTOSE-6-PHOSPHATE RIBOSE-5-PHOSPHATE ERYTHROSE-4-PHOSPHATE DIHYDROXY-ACETONE PHOSPHATE 3-PHOSPHOGLYCERATE PHOSPHOENOL PYRUVATE PYRUVATE ACETYL-CoA KETOGLUTARATE SUCCINYL-CoA OXALOACETATE MONO AND DISACCHARIDES POLY- SACCHARIDES FATTY ACIDS LIPIDS AMINO ACIDS PROTEIN MONO- NUCLEOTIDES RNA, DNA VITAMINS CO 2 ORGANIC COMPOUNDS HETEROTROPHS AUTOTROPHS LIST IS NOT ASSIGNED 6

PENTOSE BIOSYNTHESIS GLUCOSE-6-PRIBULOSE-5-P RIBOSE-5-P RING STRUCTURE - RIBOSE-5-P GLUCOSE-6-PHOSPHATE CO 2 7

L-GLUTAMATE -KETO-GLUTARATE NH 4 AMMONIUM PYRUVATEL-ALANINE TRANSAMINASE ALANINE SYNTHESIS 8

+ PHOSPHOENOL PYRUVATE ERYTHROSE- 4-PO 4 6 REACTIONS AND 6 ENZYMES CHORISMIC ACID (CHORISMATE) TRYPTOPHAN (AN AMINO ACID) SYNTHESIS A. CHORISMATE FROM "KEY METABOLITES" 9 APPRECIATE !

CHORISMATE PHOSPHO RIBOSYL PYROPHOSPHATE PHOSPHO RIBOSYL ANTHRANILATE CARBOXY PHENYL AMINO- DEOXY RIBULOSE-5-P B. TRYPTOPHAN BIOSYNTHESIS FROM CHORISMATE ANTHRANILATE APPRECIATE ! 10

INDOLE GLYCEROL PO 4 L-TRYPTOPHAN SERINE GLYCERALDEHYDE- 3- PHOSPHATE 11

TAKE AWAY: FREE ENERGY; ENZYME PROPERTIES & FUNCTION; OXIDATION/REDUCTION; COENZYME PROPERTIES & FUNCTIONS; NAD+ & NADH PLUS H+; HIGH & LOW ENERGY BONDS. GLYCOLYSIS, RESPIRATION, FERMENTATION WHAT GOES IN/COMES OUT; HOW CELLS BENEFIT FROM EACH. SUBSTRATE LEVEL PHOSPHORYLATION & OXIDATIVE PHOSPHORYLATION. ELECTRON TRANS- PORT CHAIN; CHEMIOSMOSIS, PROTON MOTIVE FORCE; ATP SYNTHASE. MODES OF MICROBIAL NUTRITION/RESPIRATION; PHOTOSYNTHESIS/NITROGEN FIXATION. ANABOLISM PATHWAYS; WHAT IS INVOLVED IN TRYPTOPHAN BIOSYNTHESIS? FUNCTIONAL GROUPS, GENETIC INFORMATION AND ITS USE.

metabolism part a background 1. a. metabolism refers to all the chemical reactions which occur in...

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