The Flow of Energy In Living Systems

1. The Flow of Energy In Living Systems Unit 3: Bioenergetics Honors Biology Monkemeier

2. Thermodynamics • Thermodynamics is the branch of science that relates to energy changes (conversions from one form to another) • The Laws of Thermodynamics help to explain energy and energy changes.

3. Bioenergetics • Bioenergetics is the field of biochemistry that concerns energy flow through living systems. • All activities of living organisms involve flow of energy through living systems as well as changes in energy.

4. What is Energy? • Energy is defined as the capacity to do work. • We think of energy as existing in two states: Kinetic energy and potential energy.

5. Energy • Kinetic energy is energy of motion. Moving objects perform work by causing other matter to move. • Potential energy is stored energy. Objects that are not moving but have the capacity to do so posses potential energy.

6. The Many Forms of Energy • Energy can take many forms: mechanical energy (kinetic and potential), heat, sound, electric current, light, or radioactive radiation.

7. Heat • Because it can exist in so many forms, energy can be measured in many ways. • The most convenient measure is in terms of heat, because ALL other forms of energy can be converted into heat. • The term THERMODYNAMICS means “heat changes”.

8. Measuring HEAT (Energy) • The unit of heat most commonly employed in biological systems is the kilocalorie (kcal) • 1 kcal = 1,000 calories • 1 calorie = the amount of heat required to raise 1 gram of water one degree Celsius • Another unit that can be used is the joule. It takes 4.18 joules of energy to raise 1 gram of water one degree Celsius.

9. Organisms • Organisms require a constant supply of energy. • The ultimate source of energy for living systems is the SUN!

10. Photosynthesis • Autotrophs (Producers) use the process of photosynthesis to convert radiant electromagnetic energy into chemical energy. • Photosynthesis converts carbon from an inorganic form (CO2) to an organic form, in the process of storing energy from the SUN as potential energy in the covalent bonds between atoms of sugar molecules.

11. Oxidation – Reduction Reactions • Energy flows through living systems (organisms) as a series of oxidation and reduction reactions. • High energy electrons are stripped from one molecule (oxidizing it) and given to another molecule (reducing it). • Oxidation – reduction reactions ALWAYS occur together. • Oxidation – reduction reactions (REDOX reactions) play a key role in the flow of energy through biological systems.

12. Oxidation / Reduction

13. Putting it all Together! • Photosynthesis converts radiant electromagnetic energy into chemical energy. • Chemical energy is energy between the atoms of a molecule. • Cellular respiration is the process that converts chemical energy into free energy. • Free energy is energy that is available to do work immediately. • Free Energy is stored and released in a molecule of ATP.

14. Photosynthesis and Cellular Respiration

15. Bioenergetics and Thermodynamics • Bioenergetics studies the flow of energy through living systems (organisms). • As energy flows through living systems and is converted from one form to another, it is governed by the Laws of Thermodynamics. • The next PPT will relate to the Laws of Thermodynamics.

16. Next PPT • The Laws of Thermodynamics