Forms and Laws of Energy

Study Notes

Energy flows into ecosystems as sunlight and leaves as heat, while essential chemical elements are recycled.
Electromagnetic waves (sunlight) are the energy capacity to cause change in matter rearrangements.
Energy exists in different forms in the environment.
Heat can be converted from mechanical energy to electrical energy.
Kinetic energy, thermal energy (heat), light energy, potential energy, and chemical energy are forms of energy.
Thermodynamics studies energy transformations in systems (collections of matter).
Living systems are open systems, exchanging energy and matter with surroundings.
Systems include the system and surroundings; the universe includes both.
There are different types of systems.

Thermodynamics considers heat (therme) and transformations (dynamis).
The first law of thermodynamics states that energy in the universe is constant; it can be transferred and transformed but not created or destroyed.
The first law has two types of changes: transfer and transformation.
Transfer includes conduction (solid-to-solid heat), convection (liquid-to-liquid heat), and radiation (gas).
The second law of thermodynamics states that every energy transfer increases disorder (entropy), and living organisms are open systems with these energy transfers.
Entropy describes energy unavailable for work; it increases in every transformation.
An example is the food chain with varying energy transformation efficiency at each trophic level (production percentages).

ATP (adenosine triphosphate) is the energy currency of cells.
GTP is another energy form that powers cellular work.
ATP has three phosphate groups, a ribose, and an adenine structure.
ATP performs three types of cellular work (transport, mechanical, and chemical).
ATP is regenerated by phosphorylation of ADP; ADP is two phosphates.
Hydrolysis (using water to break bonds) releases energy from ATP to ADP
This energy is used for cellular processes (chemical work, mechanical work, and transport work).

Plant cells use chloroplasts, grana, thylakoids, and chlorophyll (alpha and beta) to capture sunlight's energy for photosynthesis.
Carotenoids are pigments that absorb energy and provide color.
Chlorophyll absorbs all colors of light accept green which is reflected.
Carotenoids are light-absorbing pigments that assist in photosynthesis.

Chlorophyll molecules absorb light energy and excite electrons (causing electrons transition levels) to higher energy levels.
The excited electrons are transferred to other molecules, moving energy.
This process occurs in photo systems.