Bioenergetics Flashcards

1
Q

first law of thermodynamics

A

energy cannot be created or destroyed. total energy in system remains constant.

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2
Q

units for energy consumption/release

A

kCal: amount of heat energy needed to raise temp of 1 kg of water up 1C.
kJ: one columb-volt: convert enerty to electrical units

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3
Q

second law of thermodynamics

A

reactions proceed in disorderly fashion, contributing to entropy of system..

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4
Q

red-ox coupled rxn

A

oxidized: loss of electron

reduced = gain of electrons.

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5
Q

what does gibbs free energy measure?

A

free energy change of reaction (kJ)
negative = exergonic
positive = endergonic

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6
Q

actual dG affected by?

A

temp, concentration of substrates; concentration of products.

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7
Q

reduction potentials represent?

A

equimolar concentrations of reduced and oxidized forms of a molecule at equilibrium.

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8
Q

E (subscript)0 =?

A

measures tendency of molecule to gain/lose electrons relative to redox potential of hydrogen (Eh)

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9
Q

what happens if H2 and O2 are mixed together?

A

nothing without a catalyst.

spark or bacterial hydrogenase = make water.

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10
Q

electron transfer in exergonic + endergonic rxn

A

exer: electron from more (-) to more (+). catabolic
ender: e- from more (+) to more (-). anabolic.

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11
Q

most efficient e- acceptor? e- donor?

A

acceptor = O2; donor = H2 or organic carbon.

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12
Q

bacteria thrive when? fuel + oxidant =?

A

reduced fuel source and poewrful oxidant

if dG is negative = still make a living.

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13
Q

characteristics of enzymes

A

proteins; increase rate by lower activation energy, not transformed by rxn. holoenzymes are apoenzyme + cofactor (closely bonded prosthetic groups , or loose and detach)
specific binding sites.

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14
Q

mechanism of enzyme rxn

A

increase rate of reaction, do not alter its equilibrium or its standard free energy.
-> lower activation energy

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15
Q

how is activation energy lowered

A

bring cubstrates closer together in proper orientation, prosthetic groups enhance reactivity.

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16
Q

factors that affect enzyme activity

A

pH, temp. = must be optimal. short rang eof optimum.

17
Q

what is competitive inhibition

A

enzymes bind substrates with similar structure. some drugs target this way to inhibit enzyme. concentration of inhibitory or natural substrate increases that substrate binding.

18
Q

allosteric regulation = 3 key points

A

effector binds to inhibit/promote alternate substrate binding.
effector binds reversibly. causes conformational changes in catalytic site.

19
Q

positve.negative effector

A

positive cause binding of substrate + catalysis.

negative - prevents substrate binding

20
Q

feedback inhibition of sequential reaction

A

end product is negative modulator. inhibits first enzyme.

21
Q

feedback inhibition : branched reaction

A

products inhibit first enzyme that makes their product. inhibit self, other path not affected.

22
Q

covalent modification

A

reversible addition of chemical group to activate or inhibit enzyme activity. in equilibrium of other forms of enzyme.