Sec. 8.1, How Organisms Obtain Energy Main Idea: All living organisms use energy to carry out all biological processes.

Transformation of Energy Energy—the ability to do work Cells are sites of constant activity and this requires lots of energy. Thermodynamics—the study of the flow and transformation of energy in the universe

Laws of Thermodynamics First law of thermodynamics: Also called the law of conservation of energy Energy cannot be created or destroyed but can be converted from one form to another. Second law of thermodynamics: Energy cannot be converted without the loss of usable energy. Unusable energy (disorder/entropy) increases.

Autotrophs and Heterotrophs ALL organisms need energy Autotrophs—make their own food Heterotrophs—ingest food to obtain energy Nearly all energy for life comes directly or indirectly from the Sun.

Metabolism All the chemical reactions in a cell make up the cell’s metabolism. Metabolic pathways result in the continual flow of energy in an organism and in ecosystems. Photosynthesis—the pathway where light energy from the sun in converted to chemical energy (food) to be used by the cell Cellular respiration—the pathway where organic molecules are broken down to release energy to be used by the cell

ATP: The Unit of Cellular Energy ATP (Adenosine triphosphate) is the biological molecule that provides chemical energy; it’s an energy carrier molecule. Structure: a nucleotide made of an adenine base and 3 phosphate groups Function: to release energy when one of the phosphate bonds is broken

There is a continuous cycle of breaking and reforming of phosphate bonds to supply energy and ATP.