Bioenergetics.

Question 1

Define Bioenergetics.

Answer 1

The study of energy changes during biochemical reactions that takes place inside of the body.

Question 2

What are the two types of Bioenergetics?

Answer 2

Endogenic - Energy consumption
Exogenic- Energy release

Question 3

Define Thermodynamics

Answer 3

Laws and principles describing the flow and interchanges of heat, energy and matter in systems

Question 4

List the three types of systems

Answer 4

1. Isolated
2. Open
3. Closed

Question 5

Describe each system (Isolates, Closed and Open)

Answer 5

Isolated - matter nor energy can not be exchanged with its surroundings
Closed- where energy can be exchanged but not matter with its surroundings
Open- Both matter and energy can be exchanged with its surroundings.

Question 6

Give an example of each system.

Answer 6

Isolated- Thermos
Closed- Conclave flask w/ stopper
Open- Human body, beaker

Question 7

What is the 1st law of thermodynamics and give an example (explain).

Answer 7

1st law- The total number of energy in a system remains constant.
Ex. Photosynthesis - The plant absorbs solar energy —> chemical energy.
Melting of ice- absorption of heat changes the state of the ice.
Kinetic energy- car used energy to move and converts it to heat energy when placed on brakes.

Question 8

What is the 2nd law of Thermodynamics and give an example (explain)

Answer 8

The total entropy of a system must increase for a process to occur spontaneously.
Example - Heat will flow from hot coffee cup to hand because it will be more disordered if it is more dispersed

Question 9

How does Gibbs free energy differ from activation energy?

Answer 9

Gibbs free energy looks at the thermodynamics if the reaction will occur and activation energy looks at the actual energy required for reaction and build on the thermodynamics.

Question 10

Describe the three different states of a Gibbs free energy that can occur in a reaction.

Answer 10

If ΔG:

• is negative – rxn is exergonic, energy is lost from system, spontaneous from A → B
  •is positive – rxn is endergonic, energy is required by system from surroundings for rxn to occur
  •equals zero – rxn is at equilibrium; no direction favoured

Question 11

What are the two factors ΔG is determined by?

Answer 11

1) Enthalpy (ΔH) - change in heat of the products/ reactants in a rxn
2) Entropy (ΔS) - change in randomness/ disorder in products/ reactants in a rxn.

Question 12

What is the equation for ideal gas reactions as it related to ΔG?

Answer 12

ΔG = ΔG° + RTln(B/A)

Question 13

Terminal phosphate bonds are known as what?

Answer 13

High energy, they release a large amount of energy on hydrolysis/ breakdown.

Question 14

Terminal phosphate bonds allow what?

Answer 14

1) ATP to release energy
2) ADP to store energy

Question 15

Based on the Gibbs free energy equation, what factors can lead to the occurrence of a spontaneous reaction?

Answer 15

ΔG= ΔH – TΔS

as Δ S increases, ΔG becomes more -ve

Question 16

How do we determine if a Biochemical pathway is feasible?

Answer 16

• Thermodynamically for a pathway
  • feasibility depends on sum of individual ΔG’s’

-As long as the sum of ΔG is –ve the pathway is feasible

e.g if there are 6 reactions and one has a positive value the reaction will still occur/ be spontaneous if the sum of the 6 reactions is negative

Question 17

Under what circumstance can an rxn with a +ΔG occur?

Answer 17

1) If an enzyme is present.
It reduces the activation energy of the rxn
It facilitates the coupling of reactions in some cases.