Biochem Muscle Weakness Self Study
Terms
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catabolism vs anabolism
ox/red
ATP use/gen
exergonic/endergonic -
catab:
oxidative, ATP generation, exergonic
anab:
reductive, ATP use, endergonic -
metabolic rate
basal metabolic rate -
enthalpic change
normal heat production/time
basal: resting state - what metabolic processes are reflected in basal metabolic rates?
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involunatry muscle work
osmotic grad maitenance
body temp
turnover/syn of cell constituents -
Are the reactions A->B and B->C coupled?
how can A->B and c->D be coupled - coupling can occur provided delta G is neg, need a common intermediate, in an enz cat rxn the intermediate may exist only on the enz
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NAD and NADP have the same standard reduction potentials,
but in the CELL NADP has a much more neg red. potential
which of the two nt's are more reduced? - NADP b/c lower reduction potential means more of your species is reduced, the nernst equation shows this
- reduction potentials
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relative affinity of the system for electrons compared to protons (- is a weaker affinity, + is higher)
note
nernst eqn gives the relationship b/w reduction potentials and ratio of (ox)/(red) - high energy bond
- A large negative standard Gibb's free energy of hydrolysis
- what is the mimimum value for a high energy bond
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-7 kcal/mol(more neg = better)
as is seen in the ATP phosphoanyhdride bond -
AMP + ATP -> 2 ADP
what enz does this -
adenylate kinase
amp is often the product of a rxn, so converting it will often drive a rxn to the right -
PPi + H2O -> 2Pi
what enz does this - pyrophosphatase
- metabolic pool
- a number of molecules that behave simultaneously reacting with the same enz and pathways
- nucleotide pool
- ATP ADP AMP rapidly interconvert and their concentrations can vary depending on E use, but the total [] of nucleotide pool varies slowly
- describe energy charge
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0 = all amp
1 = all atp - question 5 pg #365
- ??
- rates of reaction are quantitatively controlled by the workload
- kjb
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reduction potentials
large vs small number -
the smaller the number, the more reduced species there is according to the nernst equation, general rule of thumb as redox potentials as the gimme factor are skewed because they rely on the concentrations.
SMALLER NUMBER MEANS THERE IS MORE REDUCED SPECIES PRESENT - catabolism makes or uses ATP?
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makes atp, it is an exergonic reaction
anabolism is coupled to the hydrolysis of ATP - how many high energy bonds does ATP have?
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only 2
AMP has none - what types of bonds does ATP have?
- phosphoanhydride
- what does glutamine synthase do?
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makes glutamine from glutamate and ATP,
example of the typical use of a SINGLE phosphoanhydride bond - Glutamyl tRNA synthetase what does it do
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it makes glutamyl-tRNA from glutamate ATP and tRNA
example of typical use of two phosphoanyhdride bonds -
co substrate
prosthetic group -
prosthetic group
organic - coenzyme (vitamins)
inorganic
note: not all coenz are prosthetic groups, some are loosley bound and are then called cosubstrates(weakly assoc and get changed)
cofactor - in certain enz metal ion is neither cosubstrate or prosthetic group - what is the equation for energy charge?
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1/2 [ADP] + 2ATP
AMP + ADP + ATP
fraction of high energy bonds to max high energy bonds possible - what are three ways to say ATP is plentiful?
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high energy charge
resting cell
large negative delta G - what is the most sensitive parameter of change in adenine nucleotide pool and cytosol of cell?
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AMP levels
this usually initiates the response to decreased ATP
ie stimulates PFK in glycolysis - two ways to control enzymes of a pathway
- enzyme activity and amount of enzyme
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critical control of a pathway
(2) -
covalent regulation: p of a ser/thr, result of a balance between kinase and phophatase
control through the balance between the activities of two enzymes, one that does an irrev rxn one way and another that does the same rxn the opp way, this amplifies control of the catabolic pathway
ie PFK and frc1,6di phosphatase
THIS IS known as substrate cycling - substrate cycling control
- see page 368