Lesson 1: How Organisms Obtain Energy

Vocabulary flashcards covering energy transformation, thermodynamics, metabolic pathways, cellular respiration, photosynthesis, and ATP from Lesson 1.

Energy

The ability to do work, required for cellular processes.

Thermodynamics

The study of the flow and transformation of energy in the universe.

First Law of Thermodynamics

The Law of Conservation of Energy, which states that energy can be converted from one form to another, but it cannot be created or destroyed.

Second Law of Thermodynamics

The principle stating that energy cannot be converted without the loss of usable energy; that is, entropy increases.

Entropy

Disorder or unusable energy in a system.

Autotrophs

Organisms that make their own food, either using energy from the Sun or from inorganic substances.

Heterotrophs

Organisms that ingest food to obtain energy.

Metabolism

All of the chemical reactions that take place inside a cell.

Metabolic Pathway

A series of chemical reactions in which the product of one reaction is the substrate for the next.

Catabolic Pathways

Metabolic pathways that release energy by breaking down larger molecules into smaller ones.

Anabolic Pathways

Metabolic pathways that use energy to build larger molecules.

Photosynthesis

An anabolic and endothermic pathway occurring in chloroplasts in which light energy from the Sun, carbon dioxide ($CO_2$), and water ($H_2O$) are converted into stored chemical energy (glucose) and oxygen ($O_2$).

Cellular Respiration

A catabolic and exothermic pathway occurring in mitochondria in which organic molecules (glucose) and oxygen ($O_2$) are broken down to release energy (ATP), carbon dioxide ($CO_2$), and water ($H_2O$) for use by the cell.

Adenosine Triphosphate (ATP)

The primary biological molecule providing chemical energy for cellular processes; a nucleotide composed of an adenine base, a ribose sugar, and three phosphate groups.

Adenosine Diphosphate (ADP)

A molecule consisting of an adenine base, a ribose sugar, and two phosphate groups; formed when ATP releases energy by losing a phosphate group, and converted back into ATP when a phosphate group is added.

Chloroplast

The cellular organelle that serves as the site of photosynthesis in autotrophic cells.

Mitochondria

The cellular organelle that serves as the site of cellular respiration.