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51 Cards in this Set
- Front
- Back
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metabolism
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sum of chemical changes that convert nutrients into energy and pdts.
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carbon sources
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autotroph-CO2
heterotroph- organic C |
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energy sources
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phototrophs- light
chemotrophs- organic chemical, redox rxns |
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flow of energy in biosphere
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solar:primary for life, converted to chemical energy
photoautotrophic to glu & O2 to heterotrophic to H2O & CO2 |
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catabolism
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oxidative degradative
gives simple molecules yields energy exergonic, releases ATP |
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anabolism
(occurs simultaneously with catabolism) |
biosynthetic
assembles complex molecules requires energy endergonic, uses ATP |
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catabolism rxn
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e-yielding:CHO,fat,protein
intermediate: oxidative energy poor pdt:H2O,CO2,NH3 |
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anabolism rxn
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precursors:aa,sugar,FA,N-base
intermediate:reductive macros:prot,polysac,NA,lipids |
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commonality of both rxns
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the intermediates contain a combination of NADH(reducing) and ATP(energy). Pdts from one pathway provide substrate for other pathways.
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organization in pathways
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consist of sequential steps
enzymes can be separate can form multienzyme complex otherwise known as metabolons |
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organization of multienzyme pathways
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substrate:physically separated soluable enzymes.
pdt:multienzyme complex lipid bilayer: mem bound |
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amphibolic
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the intermediates have roles in cata & ana-bolism
(pyruvate in glycolysis and gluconeogensis) |
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independent cata/anabolic pathways
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activation of one mode is accompanied by reciprocal inhibition of the other mode.
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ATP cycle
(carries E from photosynthesis or cata to the e-requiring cell processes) |
phototroph:light transfomed into ATP
heterotroph:cata pduces ATP that drives cell activity |
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ATP structure
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2 pyrophosphate linkages that release large amounts upon hydrolysis
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ATP cycle in cells
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ADP + P (in:O2 and fuel) to
catabolism (out:CO2,H2O) to ATP to hydrolysis,biosynthesis,motility |
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redox in metabolism
(cata) |
oxidative, S lose reducing equivalents, usually hydride ions captured by NAD+
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redox in metabolism
(ana) |
reductive, NADPH provides reducing power(e-) for anabolic processes
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carbon atoms in biomolecules
most reduced to most oxidized |
CH2
H-C-OH C=O OH-C=O O=C=O |
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electron carriers
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NADH + H:cata pdtion by glycolysis and TCA oxidized to pduce ATP by ETC/OP
NADPH + H:cata pdtion during pentose-P pathway that donates e- during ana |
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electron carrier rxn
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the reduction pictures more H atoms wedged or dashed depending on the plane (acetaldeyde, CH2C(=O)H + H)
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transfer of reducing equivalents from cata to ana via NADPH cycle
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cat:reduced fuel to oxidized pdt(in:NADP+ and out:NADPH)
ana:oxidized precursor to reduced biosynthetic pdt (in:NADPH and out:NADP+) |
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nutrition in macronutrients
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CHO:provide E and components for nucleotides and NA
lipid:provide FA for mem's and signal molecules protein:source of N and aa |
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vitamins and minerals in micronutrients
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diet requires, organism dependent
precursors=coenzymes (not vitC) |
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Coenzymes
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provide chemical function to rxns
act as carriers of specific functional groups usually modified and then converted back by other enzymes |
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vitamin B1
(thiamine pyrophosphate TPP) |
TPP is the active form
catalyzes decarboxylations of alpha-keto acids and formation and cleavage of alpha-hydroxyketones (beriberi, CNS disease) |
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vitamin B1 structure
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vit B1:pent,hex, R has OH
TPP:pent,hex,R has substitute TPP participates in rxns where carbonyl C's are cleaved or synthesized. It stabilizes the - on the carbonyl C (occurs in yeast) |
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adenine nucleotide coenzymes
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solely for binding to enzyme
adenine increases affinity and specificity of coenzyme for site on enzyme |
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classes of coenzymes
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1.pyridine dinucleotides(NADH,NADPH)
2.flavin mono/dinucleotides (FADH) 3.coenzyme A (Co-A) |
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nicotinic acid and the nicotinamide coenzymes (pyridine nucleotides)
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ARE TWO ELECTRON CARRIERS:
1.transfer H- to/from substrates (redox rxns) 2.facilitated by dehydrogenase 3. 2 important coenzymes: NAD+ and NADP+ |
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nicotinic acid and the nicotinamide coenzymes(pyridine nucleotides)
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sturcturally related to tobacco alkaloid
aka NIACIN *absence of dietary nicotinic acid-pelagra in humans,"blacktongue" in dogs |
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nicotinamide coenzymes states
(hexagon: 2 or 3=, O=C-NH2) |
oxidized: 1 "in plane" H on the hexagon
reduced: 2 wedged H on the hexagon |
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riboflavin and the flavins
(vit B2) |
active forms FMN and FAD
FMN: not a true nucleo FAD: not a dinucleotide |
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flavin mechanisms
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flavins are 1 or 2 e- transfer
1.oxidized quinone-yellow 2.semiquinone-blue,red (reduced is colorless) |
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coenzyme A
[pantothenic acid(vit B3) is a component] |
two main functions
1.activate acyl groups for transfer by nucleophilic attack 2.activate the alpha-H of the acyl for abstraction as a proton (mediated by the reactive -SH group on CoA that forms thioesters) |
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Coenzyme A structure
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thioester @ -SH
adenine nucleo @ other end (acts as recognition site) 1.hydrolysis of thioester > favorable then O2 esters 2.tranfer of acetyl from CoA to nucleophile 3.acetyl-CoA has high group transfer potential |
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vitamin B6 (pyridoxine and pyridoxal phosphate)
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1.catalyzes rxns that have aa
2.transaminations,decarboxylations,eliminations,racemizations,aldol rxns (versatile chem: schiff base adducts with an alpha-a of aa, e- system stabilizes intermediates) |
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Schiff base and rxn
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R-NH2 + O=CH-R --> R-N=CH-R + H2O
(amine plus aldehyde yields schiff base plus water) |
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vitamin B12 (cyanocobalam)
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catalyzes 3 kinds of rxns:
1.intramolecular rearrangements 2.reductions of ribonucleotides to deoxyribonucleotides 3.methyl transfers |
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structure of cyanocobalamin and forms of vit B12
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corrin ring with cobalt ion
similar to heme porphryin ring (8 pentagons with ball in center with various R groups) |
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vitamin B12 function
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rearrange: inverse top H and R
reduction: from 2OH to OH & H transfer:sub CH3 in place of R group (ie: -SH) |
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vitamin C (acorbic acid)
[not really a vitamin] |
made by plants and animals
lack L-gulono-gamma-lactone oxidase strong reducing agent functions as e- carrier |
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roles of vitamin C
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strong reducing=radical scavenger
1.hydroxylations of proline and lysine are vitC dependent 2.metab of Tyr in brain " " 3.prevent toxic effect of metals 4.ameliorates allergic responses 5.stimulate the immune system |
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biotin
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function as mobile carboxyl carrier
bound covalently to lysine residue biotin-lysine=biocytin biotin ring tethered to protein by long chain |
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biocytin structure
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both are similar:
biotin has 2 pentagons, 1 w/ 2NH and =O, other with S lysine has NH with =O not pentagon (chain carries groups bw enzymes) |
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biotin carboxylations
(must use bicarbonate and ATP) |
requires ATP and CO2 or HCO3
1.activation by ATP creates carbonyl-P 2.carboxyl transferred to biotin & forms N-carboxy-biotin |
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biotin-dependent carboxylations involving ATP and bicarbonate
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ATP + HCO3 + .....
pyruvate ---> oxaloacetate acetyl-CoA ---> malonyl-CoA proplonyl-CoA ---> methylmalonyl-CoA |
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lipoic acid
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like biotin, ring on chain and liked to lysine on its protein.
is an acyl group carrier found in pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase functions to couple acyl group transfer and e- transfer during oxidation and decarboxylation of alpha-keto acids |
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forms of lipoic acid
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oxidized:pent with S-S,6C chain and the last is O=C-O
reduced:pent with SH-SH and same following lipoamide complex: S-S,=O,2NH |
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folic acid
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folates are acceptors donors of 1-C units for all oxidation levels of C except CO2!
active form:tetrahydrofolate (THF) formed by two reductions of folate by dihydrofolate reductase |
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fat soluable vitamins
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vit action mediated by receptors
vitA:development, differentiation vitD:bone maintenance, Ca metab |
