Lecture 1: Introduction to Bioenergetics

Question 1

Give 6 roles of mitochondria.

Answer 1

1) produce about 90% of cellular energy
2) regulate cellular redox status
3) maintain calcium homeostasis
4) produce Reactive Oxygen Species (ROS)
5) synthesise and degrade high-energy biochemical intermediates
6) regulated apoptosis (programmed cell death)

Question 2

How many electrons does it take to reduce oxygen to water?

Answer 2

4

Question 3

What are ROS?

Answer 3

Reactive Oxygen Species (ROS) are a group of compounds derived from the incomplete reduction of molecular oxygen. 
Examples include:
- the superoxide anion (O2.-)
- hydrogen peroxide (H2O2)
- the hydroxyl radical (OH.)
O2 - 1 e- = O2.-
O2.- -1 e- = H2O2
H2O2 - 1e- = OH.

Question 4

What is oxidative stress?

Answer 4

An imbalance in ROS-generating and ROS-scavenging systems, which can cause damage to cells and cause disease.

Question 5

Why is life improbable?

Answer 5

Increased order, so decreased entropy

Question 6

What are the two indispensable prerequisites for life?

Answer 6

Information and energy, which are both provided by nucleosides - ATP, GTP for energy world and RNA and DNA for information world.

Question 7

What is energy?

Answer 7

Energy is the ability to cause a specific change.
OR
Energy is the capacity to do work.

Question 8

Give 5 categories of change energy can work on.

Answer 8

• Synthetic (synthesis or degradation),
• Mechanical (muscle contraction, flagellum, etc)
• Concentration (moving molecules/ions against a concentration gradient)
• Electrical (specialised concentration gradient with voltage, movement of charged ions)
• Heat (vast amount of energy used to maintain body temperature at 37 degrees)

Question 9

Give three sources of energy.

Answer 9

Solar radiation, electrical discharge, chemical

Question 10

What are open and closed systems?

Answer 10

Closed thermodynamic systems have no exchange of energy with the surroundings. Open thermodynamics systems do exchange energy with the surroundings. A living organism must be an open system.

Question 11

What is bioenergetics?

Answer 11

The application of thermodynamic principles to reactions and processes in living systems.

Question 12

What are bioenergetics different to classical thermodynamics?

Answer 12

Classical thermodynamics, also called equilibrium thermodynamics, apply to reversible reactions in a closed system, where equilibrium is reached.

Living systems can NOT be at equilibrium. This would cause death. Non-equilibrium state can be sustained as long as energy is obtained from the surroundings.