5 Bioenergetics - Lecture

Question 1

Potential Energy

Answer 1

objects not in motion but have capacity to do work

Question 2

Kinetic Energy

Answer 2

energy of motion (ex. ions rushing into cell)

Question 3

Thermodynamics

Answer 3

study of energy transfer what goes in = what comes out

Question 4

1st Law of Thermodynamics

Answer 4

Energy can be neither created nor destroyed. It can only be converted from one form to another.

Question 5

Examples diff forms of energy can be inter-converted:

Answer 5

1)PE due to position to KE to Heat E 2)Chemical Bond E in water and O2 to rapid molecular motions in water to heat E

Question 6

ΔE

Answer 6

-The change in internal energy of a biological system -E transformations consider the system & environment -relates to heat & work -NOTHING to do with spontaneity - ΔE = Q-W Q = heat energy W = work energy

Question 7

2nd Law of Thermodynamics

Answer 7

-energy transformations occur spontaneously so that matter is transformed to a more random state -Reversal of tendency towards entropy requires energy

Question 8

Gibb’s Free Energy

Answer 8

-the E available to do work ΔG = ΔH - TΔS ΔG=change in available E ΔH= change in enthalpy TΔS=unavailable E (lost as entropy) potential factor: T in Kelvin or DegC + 273 capacity factor: entropy (ΔS calories (E)/degrees)

Question 9

Exergonic reactions:

Answer 9

-Products contain less energy than reactants –energy is released. -They are spontaneous because they require no input of energy (Note: This does not mean “fast.”

Spontaneous

Releases Free Energy ( -ΔG)

Products have less energy than reactants

Question 10

Endergonic reactions:

Answer 10

-Products contain more energy than reactants. -Non-spontaneous - require an input of energy.

Not Spontaneous

Must consume Gibbs Free Energy (+ΔG)

Products have more energy than reactants

Question 11

+ΔG

-ΔG

ΔG=0

Answer 11

spontaneous (exergonic)

non-spontaneous (endergonic)

at equilibrium

Question 12

Are chemical rxns in cell reversible?

Answer 12

YES

Question 13

What is the:

dissociation rate? K_off

association rate? K_on

Question 14

At equilibrium: the association rate ____ dissociation rate

formula?

Answer 14

=

Keq = [AB] / [A] [B]

(K_on/K_off)

Question 15

Free energy changes in chemical reactions at standard conditions…explain:

What is standard free E equation?

Answer 15

ΔG^o’ = - RTlnK_eq or

ΔG^o’ = - 2.303 RTlogK_eq

ΔG^o’ = standard free energy at standard conditions, where T=25C (298K), 1 atm pressure, all reactants and products are at 1 M concentration, except for water is present at 55.6 M, and pH = 7.0.

Question 16

Free energy changes under non-standard conditions:

Answer 16

(reality in cell)

ΔG = ΔG^o’ + RT ln [products]/[reactants]

or

ΔG = ΔG^o’ + 2.3(RT) log [products]/[reactants]

The free energy of any cellular reaction is a function of the nature of the reaction itself (DGo’) as well as the initial concentrations of the reactants and products.

Question 17

What is bioenergetics?

Answer 17

the study of the flow and transformation of energy in and between living organisms and between living organisms and their environment

Question 18

Types of Energy used or produced by cells: (6)

Answer 18

• Chemical energy
• Mechanical energy
• Heat or thermal energy
• Sound
• Electrical energy
• Light or electromagnetic energy

Question 19

Living cells produce exquisitely ordered structures with a high or low entropy?

Answer 19

low entropy (disorder)

Question 20

How do cells maintain increased order?

Answer 20

a system (i.e. the cells) can sustain an increased order if the entropy in the surroundings (i.e. outside the cell) increases. The end result is that the entropy in the universe increases.

In biological systems, heat lost to the environment, increases the random movement of molecules in its surroundings to increase disorder.

obey 2nd law of thermodynamics

Question 21

Energy Cycle (pic)

Question 22

Describe free energy & entropy in:

anabolic rxns

catabolic rxns

Answer 22

anabolic:

free E inc. entropy dec.

catabolic:

free E dec. entropy inc.

Question 23

photosynthesis:

Question 25

metabolism:

Answer 25

is the sum of all anabolic and catabolic reactions in a cell or organism.

Anabolism;Condensation polymerization;Deyhydration synthesis;endergonic

Catabolism;Hydrolysis;exergonic

Question 26

Mammalian cells metabolize _____ to produce ____ (hypoxic conditions) or ___ (anoxic conditions)

Answer 26

carbohydrates ATP NAD+

Question 27

Glycolysis?? double check in book

Question 28

Mitochondria completes the ___ of ___ by converting ___ to ____

Answer 28

oxidation carbohydrates pyruvate stored energy (ATP)

Question 29

ATP synthase generates __ inside the ___

Answer 29

ATP mitochondria

Question 30

ATP synthase in the inner mitochondrial membrane drives the synthesis of ATP using the ___________

Where is [H+] gradient high in? low in? What is stored as?

Answer 30

[H+] gradient (potential energy)

The elecrochemical [H+] gradient (high in inner membrane space/low in mitochondria matrix) is stored potential energy

Question 31

ATP: energy is stored in __ high-energy ___ bonds

Answer 31

2 phosphate

Question 32

ATP hydrolysis is highly energetically ______

ATP =

Answer 32

favorable (exergonic)

ADP + Pi

Question 33

favored rxn?

equilibrium?

disfavored rxn?

Answer 33

ΔG < 0 favored reaction (Spontaneous)

ΔG = 0 neither the forward nor the reverse reaction prevails (Equilibrium)

ΔG > 0 disfavored reaction (Nonspontaneous)

Question 34

What drives most of the endergonic reactions that occur in a cell?

Answer 34

ATP

Question 35

Reaction coupling allows energetically-___ reactions (+ΔG) to be driven by ___ ones (-ΔG) (unfav or fav?)

Reaction coupling with ___ reactions drives most ____ reactions in the cell (endo exo?)

Answer 35

unfavorable favorable

exergonic endergonic

Question 36

The Metabolism of Living Cells Maintains ___ Intracellular ATP Concentration (low or high?)

Cells maintain a steady state (where reactants and products remain relatively constant) having a ___ [ATP].

Is [ATP]/[ADP] is at equilibrium? At equilibrium, there’s more:

cells must have stored E to live

Answer 36

High

high

Never ADP