Bioenergetics

zero

1st law of thermodynamics state the energy is neither created nor destroyed which means that the delta E is ___

increasing

2nd law of thermodynamics state that the entropy of the universe is always ___

water

___ is the driving force of hydrophobic interactions as it tries to form less cages and increase entropy

work

an organism must be able to do ___, in order to remain ordered in opposition of the universe’s tendency to disorder e

energy

___ is the capacity to do work

sunlight

the major, original source of energy for most life on earth

• can be calculated using this equation:

reduced

complex, ___ compounds are potential sources of energy

gibbs free energy

the energy of molecules in a solution required to do work; impacted by temperature, pressure, and concentration

∆G

the maximum amount of energy potentially available for useful work at a constant temperature and pressure, consistent with the conditions seen in the cell; tells you what the reaction will do under actual cellular conditions

∆Gº’

tells you the inherant tendency of a reaction

at equilibirum

when ∆G = 0, this means the reaction is ___

heat

if an exergonic reaction occurs by itself, the energy will be lost as ___

energy coupling

when the energy released from an exergonic reaction is used to drive an endergonic reaction

mechanism of reaction

a negative ∆G does not guarentee a reaction will happen, it depends on the ___, which is independent of ∆G

standard state

P = 1 atm

T = 25 ºC (298 K)

concentration of reactants and products = 1 M

reaction quotient

K_eq when the reaction is not at equilibrium; used to calculate ∆G at a random point in the reaction

K_eq

used to get ∆Gº’

inverse

Keq’ and ∆Gº’ have an ___ relationship

spontaneous

the oxidation of glucose into CO₂ and water is a ___ process

non-spontaneous

the assembly of glucose from simple molecules is ___; driven by photosynthesis in plants

metabolite concentrations

cells regulate ___ to alter ∆G and drive reactions in the desired direction

energy quanta

units of energy released gradually to control the release of energy from high-energy reactions like the combustion of glucose; reduced electron carriers and nucleotide triphosphates

-2840 kJ/mol

energy released from the combustion of glucose

oxidation state

(# of bonds to O, N, and S) - (# of bonds to H)

+4

the highest oxidation state for carbon

-3

the lowest oxidation state for carbon

electrons

the direction of electron flow in redox reactions is determined by the affinity of ___ by the atoms compared to the affinity of a proton to form hydrogen gas under biochemical standard conditions

standard reduction potential (Eº)

the affinity for electrons (V); determined by a voltmeter measuring the voltage difference between 2 half cells

reductions

all half reactions are written as ___

+ Eº’

strong oxidizing agent, reduced; substance has a high affinity for electrons

- Eº’

strong reducing agent, oxidized; substance has low affinity for electrons

net potential (∆Eº’)

Eº’_{(electron-acceptor)} - Eº’_{(electron-donor);} oxidized - reduced; reducing agent - oxidizing agent

FMN and FAD

electron carrier that can donate or accept two electrons and two protons and are tightly bound to their enzyme, and cannot diffuse away from their enzyme

NAD/NADH

electron carriers that accepts electrons from catabolic degradation and then delivers the elctrons to the mitochondrial electron transport respiratory chain; oxidized form accepts 2 electrons and a proton

NADP/NADPH

electron carrier that supplies electrons for synthetic pathways; oxidized form accepts 2 electrons and a proton

ATP

energy currency that serves as a major linking intermediate between energy yielding and energy requiring reactions

hydrolysis

ATP ___ yields free energy because:

1. it causes release of charge repulsion

2. there are more resonance forms of ADP + P_i than ATP which increases ∆S

3. ADP dissociates 1 proton and has 3 negative charges capable of resonance

4. ___ is stabilized by water

phosphoryl group transfer potential

the ability of a phosphorylated compound to give up its phosphate group; the same magnitude as ∆Gº’, but with a negative charge

high

if PGTP was too ___. it would be difficult to transfer a phosphate group to it, and the energy released would be much more than what is needed for the reaction so it would be considered a waste of energy

low

if the PGTP was too ___, the energy would not be enough to do work with; this is in line with phosphate acceptors like glucose and ADP

donor

phosphoenolpyruvate is a great phosphate ___, because its product pyruvate is highly stabilized due to resonance

substrate level phosphorylation

process of making ATP that utilized energy from high PGTP molecules like PEP, 1,3-bis-phosphoglycerate, and phosphocreatine

kinases

enzymes that phosphorylate other molecules (activates them)

• increases the free energy of a molecule and adds a negative charge to it (stays in cell)

phosphatases

enzymes that dephosphorylates other molecules (deactivates them)

glutamine synthetase

enzyme that facilitates the creation of glutamine from glutamic acid and NH₃ with the help of ATP and a Mg²⁺ cofactor

thioester bonds

a form of energy currency that’s not resonance stabilized, so they store more free energy than oxygen esters

electron transport chain

a series of proteins with prosthetic groups that become oxidized and reduced alternately as electrons and proteins are passed along

• ATP is generated when the electrons created from the oxidation of electron carriers like NADH and FADH₂ are transported through this chain

• water is also created

oxidative phosphorylation

creates ATP through energy-releasing redox reactions in the mitochondria; uses ATP synthase

photophosphorylation

ATP formation couples to the energy gotten from the absorption of visible plants in the chloroplast of plants and some microorganisms

inner membrane

the electron transport chain is located in the ___ of the mitochondria which is impermeable to most small molecules and ions

matrix

the ___ of mitochondria contains pyruvate dehydrogenase, TCA cycle enzymes, and other enzymes for oxidation of amino acids and fatty acids

ubiquinone

oxidized form of coenzyme Q, a lipid soluble electron carrier that accepts 2 electrons from either Complex I or II of the ETC

ubiquinol

reduced form of conenzyme Q

cytochrome C

peripheral membrane protein electron carrier with an iron-containing heme group that transfers 1 electron from Complex III to IV

• Fe+2 → Fe+3: complex III and the reverse is done by complex IV

• has cysteine bonded to heme group through disulfide bonds

iron

in Fe-S proteins, ___ has electron carrier function because it can be oxidized and reduced

oxygen

ETC ends in the transfer of electrons to ___ which result in water, and an accumulation of proteins in the mitochondrial intermembrane space

Complex I

NADH gives its electrons to ___ at the entrance of the ETC; makes 2.5 ATP

Complex II

FADH₂ gives its electrons to ___ at the start of the ETC; makes 1.5 ATP

Complex I

4 protons pumped through the membrane

Complex II

no protons pumped across the membrane

Complex III

4 protons pumped across the membrane

Complex IV

2 protons pumped across the membrane

proton-motive force