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51 Cards in this Set

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metabolism
sum of chemical changes that convert nutrients into energy and pdts.
carbon sources
autotroph-CO2
heterotroph- organic C
energy sources
phototrophs- light
chemotrophs- organic chemical, redox rxns
flow of energy in biosphere
solar:primary for life, converted to chemical energy

photoautotrophic to glu & O2
to heterotrophic to H2O & CO2
catabolism
oxidative degradative
gives simple molecules
yields energy
exergonic, releases ATP
anabolism
(occurs simultaneously with catabolism)
biosynthetic
assembles complex molecules
requires energy
endergonic, uses ATP
catabolism rxn
e-yielding:CHO,fat,protein
intermediate: oxidative
energy poor pdt:H2O,CO2,NH3
anabolism rxn
precursors:aa,sugar,FA,N-base
intermediate:reductive
macros:prot,polysac,NA,lipids
commonality of both rxns
the intermediates contain a combination of NADH(reducing) and ATP(energy). Pdts from one pathway provide substrate for other pathways.
organization in pathways
consist of sequential steps
enzymes can be separate
can form multienzyme complex otherwise known as metabolons
organization of multienzyme pathways
substrate:physically separated soluable enzymes.
pdt:multienzyme complex
lipid bilayer: mem bound
amphibolic
the intermediates have roles in cata & ana-bolism
(pyruvate in glycolysis and gluconeogensis)
independent cata/anabolic pathways
activation of one mode is accompanied by reciprocal inhibition of the other mode.
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
ATP structure
2 pyrophosphate linkages that release large amounts upon hydrolysis
ATP cycle in cells
ADP + P (in:O2 and fuel) to
catabolism (out:CO2,H2O) to
ATP to
hydrolysis,biosynthesis,motility
redox in metabolism
(cata)
oxidative, S lose reducing equivalents, usually hydride ions captured by NAD+
redox in metabolism
(ana)
reductive, NADPH provides reducing power(e-) for anabolic processes
carbon atoms in biomolecules
most reduced to most oxidized
CH2
H-C-OH
C=O
OH-C=O
O=C=O
electron carriers
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
electron carrier rxn
the reduction pictures more H atoms wedged or dashed depending on the plane (acetaldeyde, CH2C(=O)H + H)
transfer of reducing equivalents from cata to ana via NADPH cycle
cat:reduced fuel to oxidized pdt(in:NADP+ and out:NADPH)
ana:oxidized precursor to reduced biosynthetic pdt (in:NADPH and out:NADP+)
nutrition in macronutrients
CHO:provide E and components for nucleotides and NA
lipid:provide FA for mem's and signal molecules
protein:source of N and aa
vitamins and minerals in micronutrients
diet requires, organism dependent
precursors=coenzymes (not vitC)
Coenzymes
provide chemical function to rxns
act as carriers of specific functional groups
usually modified and then converted back by other enzymes
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)
vitamin B1 structure
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)
adenine nucleotide coenzymes
solely for binding to enzyme
adenine increases affinity and specificity of coenzyme for site on enzyme
classes of coenzymes
1.pyridine dinucleotides(NADH,NADPH)
2.flavin mono/dinucleotides (FADH)
3.coenzyme A (Co-A)
nicotinic acid and the nicotinamide coenzymes (pyridine nucleotides)
ARE TWO ELECTRON CARRIERS:
1.transfer H- to/from substrates (redox rxns)
2.facilitated by dehydrogenase
3. 2 important coenzymes: NAD+ and NADP+
nicotinic acid and the nicotinamide coenzymes(pyridine nucleotides)
sturcturally related to tobacco alkaloid
aka NIACIN
*absence of dietary nicotinic acid-pelagra in humans,"blacktongue" in dogs
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
riboflavin and the flavins
(vit B2)
active forms FMN and FAD
FMN: not a true nucleo
FAD: not a dinucleotide
flavin mechanisms
flavins are 1 or 2 e- transfer
1.oxidized quinone-yellow
2.semiquinone-blue,red
(reduced is colorless)
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)
Coenzyme A structure
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
vitamin B6 (pyridoxine and pyridoxal phosphate)
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)
Schiff base and rxn
R-NH2 + O=CH-R --> R-N=CH-R + H2O

(amine plus aldehyde yields schiff base plus water)
vitamin B12 (cyanocobalam)
catalyzes 3 kinds of rxns:
1.intramolecular rearrangements
2.reductions of ribonucleotides to deoxyribonucleotides
3.methyl transfers
structure of cyanocobalamin and forms of vit B12
corrin ring with cobalt ion
similar to heme porphryin ring
(8 pentagons with ball in center with various R groups)
vitamin B12 function
rearrange: inverse top H and R
reduction: from 2OH to OH & H
transfer:sub CH3 in place of R group (ie: -SH)
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
roles of vitamin C
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
biotin
function as mobile carboxyl carrier
bound covalently to lysine residue
biotin-lysine=biocytin
biotin ring tethered to protein by long chain
biocytin structure
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)
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
biotin-dependent carboxylations involving ATP and bicarbonate
ATP + HCO3 + .....
pyruvate ---> oxaloacetate
acetyl-CoA ---> malonyl-CoA
proplonyl-CoA ---> methylmalonyl-CoA
lipoic acid
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
forms of lipoic acid
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
folic acid
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
fat soluable vitamins
vit action mediated by receptors
vitA:development, differentiation
vitD:bone maintenance, Ca metab