Chapter 10 Flashcards
What work processes in a cell require energy?
- Chemical work (complex mol)
- Mechanical work (motility/movement)
- Transport work (uptake, elim., maintenance)
Delta(E’º) and delta(G’º) for FAD/FADH2 with 1/2 O2/H2O?
(see Half-Reaction Table), LEO says GER
Delta(E’º) = E’º(reduced/acceptor) - E’º(oxidized/donor)
Delta(E’º) = 0.82-(-0.18) V
Delta(E’º) = 1 V
Delta(G’º) = -nF(Delta(E’º))
Delta(G’º) = -2(96.63 kJ/mol V)(1 V)
Delta(G’º) = -193.26 kJ/mol
Redox chemical reaction for FAD/FADH2 with 1/2 O2/H2O
FADH2 → FAD+ + 2H+ +2e-
1/2 O2 + 2H+ + 2e- →H2O
Resulting equation: FADH2+ 1/2 O2 <—> FAD+ + H2O
“Activation E”?
- E required to form TS complex
- Enzyme lowers Ea, increases rxn rate
- Enz. increases [S] @ activation site
- Enz. orients S properly to form TS complex
- Keq unchanged
How do enzymes function?
- Speeds up rxn rate @ which it proceeds towards eq’m
- Enz. increases [S] at activ. site + orients S properly
- Lock & key: only specific S will fit in Enz. to catalyze rxn
- Induced fit: S binds and Enz. changes to accommodate shape
“Michaelis constant”?
Mich. const. (Km) = [S] @ half maximum velocity (represents affinity of enz. for its substrate)
“Maximum velocity [of rxn]”?
Velocity of rxn when enzymes become saturated w/ S
How does enz. activity change w/:
a) [S]
b) pH
c) temp
a) Does not change w/ [S]
b) Increased activity @ optimal pH
c) Increased activity @ optimal temp
How is “covalent modification” used for metabolic regulation?
Add./remov. of chemical group (phosphate, methyl, adenyl) will increase/decrease activity of spec. enz. Reversible, can act as on/off switch.
Two processes that make up metabolism?
Catab: Breakdown of complex compound to provide ATP, source of reducing power, small precursor metabolites
Anab: Biosynthesis rxns to generate precursor metabs, carbs/polysaccs/AAs/nucleotides/lipids
Define “exergonic” and “endergonic” rxns
Ex (release of free G):
Keq > 1
delta(G’º) < 0
End (absorption of free G):
Keq < 1
delta(G’º) > 0
T/F: ATP breakdown is an exergonic reaction.
TRUE: ATP breakdown is exergonic but the reaction it undergoes is endergonic. Energy from breakdown is absorbed by products (more favorable)
T/F: Other energy molecules besides ATP are GTP, CTP and ADP
FALSE: ADP is formed w/ ATP breakdown and lacks E. UTP (uridine 5’-triphosphate) is the last example involved in peptidoglycan/polysaccharide synthesis.
T/F: ATP has high transfer potential.
TRUE
Define st. reduc. potential (Eº)
Measure of tendency for donor half to lose e-. More -ve = more tendency to spont. donate e-, whereas more +ve = greater affinity for e-
Electron Transport Chains (ETCs) are a set of sequential _______________ rxns that protect cell from random non-productive _______________ of other molecules: each carrier is __________ and then re-__________.
Electron Transport Chains (ETCs) are a set of sequential REDOX rxns that protect cell from random non-productive REDUCTION of other molecules: each carrier is REDUCED and then re-OXIDIZED.
T/F: The ETC is found in the plasma membrane of euk. cells.
FALSE: ETC is found in internal mitochondrial membrane in euk, but plasma memb. in prok
T/F: NAD is produced during glycolysis, TCA (Kreb’s), and beta-oxidation
FALSE: NADH is produced during these processes, not NAD
List two characteristics of NADP.
- 60% cell’s needs produced in pentose phosphate pathway (“P”)
- Used in anabolic rxns as e- source
List two flavoprotein e- carriers
FAD:
- can accept 2e-/2H+
- ETC
FMN:
- riboflavin phosphate like FAD w/out adenine nucleotide
- can accept/donate 1 or 2e-
- can mediate betw. 1e-/2e- acceptors/donors
T/F: Coenzyme Q (CoQ)/ubiquinone can accept 2e- and 2H+ on its own, but only 1e- when bound to respiratory complexes.
TRUE
What characteristic is shared between FMN and CoQ?
They can mediate between 1e- and 2e- acceptors/donors.
__________ is the non-protein group of cytochromes. They use __________ to transfer electrons.
HEME is the non-protein group of cytochromes. They use IRON to transfer electrons.
“_________” are changes in metabolite levels.
Flux
__________ are changes in metabolite levels.
FLUX are changes in metabolite levels.
What are the 6 classes of enzymes?
THILLO:
Transferase
Hydrolase
Isomerase
Lyase
Ligase
Oxidoreductase
T/F: At very low temperatures, an enzyme’s activity is initially low because the protein is denatured.
FALSE: At high levels the enzyme is denatured and activity immediately drops.
“Cofactor”?
Non-prot. component of enzyme, prosthetic group: act as carriers/shuttles for substrates betw. enzyme complexes.
Diff. betw. competitive and noncompetitive inhibitor?
Comp.:
- Direct competed w/ binding of substrate to active site
Noncomp:
- Binds to enzyme in place other than active site (which changes shape of site)
T/F: The sulfa drug is a noncompetitive enz. inhibitor for rxns involving PABA to folate.
FALSE: It is competitive and structurally similar to PABA>
T/F: The sulfa drug is a noncompetitive enz. inhibitor for rxns involving PABA to folate.
FALSE: It is competitive and structurally similar to PABA.
Differentiate betw. rxn rate graph of comp. and noncomp. enz inhibitor.
Comp:
- rxn rate is more linear than if there were no inhibitors at all, but Vmax eventually reached cuz true substrate will win comp
Noncomp:
- Plateau is reached/Vmax is lower cuz more sites will be skewed due to noncomp inhibitors
List the three major mechanisms of metabolic regulation
- Metabolic channelling/compartmentation (ex. shutting down pathways to conserveE)
- Control amnt of enz synth via transcription/translation
- Stimulation or inhibition of crit. enz activity via posttranslational regulation (reversible/irreversible)
List the three major mechanisms of metabolic regulation
- Metabolic channelling/compartmentation (ex. shutting down pathways to conserveE)
- Control amnt of enz synth via transcription/translation
- Stimulation or inhibition of crit. enz activity via posttranslational regulation (reversible/irreversible)
“Allosteric enzymes”?
- Two sites: catalytic + regulatory
- Allosteric effector binds to reg site + changes shape of catalytic site
Define feedback/end prod. inhibition
- End prod of process used to inhibit enz activity (feedback loop)
- Pacemaker enz catalyzes slowest/rate-lim rxn
- Ex. threonine and lysine used as feedback inhibitors in synth of essential AAs
