Bioenergetics

Question 1

bioenergetics definition

Answer 1

describes the transfer and utilization of energy in biological systems, concerned with the initial and final energy states, not the rxn mechanism

Question 2

system

Answer 2

all the reactants and products with a regard to a chemical rxn, the solvent, and immediate atmosphere

Question 3

types of systems

Answer 3

isolated system: no exchange of matter or energy
closed system: exchanges energy but not matter
open system: exchanges both energy and matter

Question 4

thermodynamics

Answer 4

study of energy and its effect on matter

Question 5

1st law of thermodynamics

Answer 5

energy is conserved but can be converted from one form into another

Question 6

2nd law of thermodynamics

Answer 6

all processes involving energy changes under a given set of conditions of temp and pressure, some energy is lost

Question 7

entropy (S)

Answer 7

the randomness/disorder of the components of a chemical system

Question 8

change of entropy (S)

Answer 8

max value at equilibrium
S positive randomness increases
S negative randomness decreases

Question 9

enthalpy (H)

Answer 9

measurement of energy in a thermodynamic system equivalent to total heat content of the system

Question 10

change of enthalpy (H)

Answer 10

reflects the number/kinds of chemical bonds and non-covalent interactions broken and formed during a rxn
H positive: heat is absorbed (endothermic/breaking bonds)
H negative: rxn releases heat (exothermic/making bonds)

Question 11

thermodynamics in biological systems

Answer 11

all rxns comply to thermodynamics, and occur under physioloigcal conditions
potential energy -> heat, simpler metabolic products (increase S), or more complex macromolecules (decrease S)

Question 12

coupled rxns

Answer 12

happens commonly in metabolic pathways, when biochemical rxns must consume energy to make them occur

Question 13

Gibbs free energy (G)

Answer 13

free energy of a system is the portion of the total energy in a system that is available for useful work
-determines if rxn is favorable

Question 14

change of free energy (G)

Answer 14

G=0 process is at equilibrium
negative G: favorable, exergonic, spontaneous
positive G: unfavorable, endergonic, non-spontaneous

Question 15

free energy equation

Answer 15

(delta)G= (delta)H - T(delta)S

Question 16

thermodynamic favorability depends on what

Answer 16

energy differences & conc. of [S] & [P]

Question 17

transition state

Answer 17

a state of higher free energy than both the reactant and product

Question 18

activation energy

Answer 18

the energy required to reach the “transition state” of the molecule
-decreased w/ catalysis

Question 19

oxidation

Answer 19

loss of electrons

Question 20

reduction

Answer 20

gain of electrons

Question 21

redox reactions

Answer 21

electrons are transferred from the reductant to oxidant

Question 22

redox reactions examples

Answer 22

NAD+ and FAD

Question 23

NAD+ and FAD

Answer 23

important role in citric acid cycle
-reduced to NADH and FADH2
-subsequent e- donation liberates free energy

Question 24

ATP role in free energy

Answer 24

exergonic processes are coupled to the formation of ATP
endergonic processes are coupled to the consumption of ATP

Question 25

ATP

Answer 25

contains adenine, ribose, and a triphosphate group
energy carrier/energy transfer agent

Question 26

ATP structure

Answer 26

adenosine linked by phosphoester bond followed by two phosphoanhydride bonds

Question 27

ADP, AMP, ATP

Answer 27

large free energy change from ATP to ADP, small free energy change from ADP to AMP
ADP + Pi much more stable than ATP

Question 28

why is ADP and AMP are more stable

Answer 28

ATP has four closely spaced negative charges w/ strong repulsion between them
more resonance with ADP than ATP
ionization
Mg 2+

Question 29

ATP synthesis

Answer 29

requires energy, so utilizes processes with more negative G values

Question 30

ATP exception

Answer 30

ATP hydrolysis isn’t kinetically favorable, so needs to an enzyme