Science 8: Cellular Respiration and Energy Transformations

Vocabulary flashcards covering the stages, equations, organelles, and types of cellular respiration, as well as review concepts from photosynthesis.

Cellular Respiration

The cellular process of breaking down food molecules (such as glucose) to convert stored chemical energy into usable energy in the form of adenosine triphosphate ($\text{ATP}$).

Adenosine Triphosphate (ATP)

The usable energy currency of the cell produced during cellular respiration through the breakdown of glucose.

Chemical Equation of Cellular Respiration

The overall chemical reaction representing aerobic respiration: $6\text{O}_2 + \text{C}_6\text{H}_{12}\text{O}_6 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{ATP}$.

Mitochondrion

The cellular organelle known as the "Energy Factory" where the majority of cellular respiration reactions take place.

Outer Membrane (Mitochondria)

The smooth outer phospholipid bilayer that covers and encloses the exterior surface of the mitochondrion.

Inner Membrane (Mitochondria)

The internal mitochondrial membrane that folds into cristae to provide increased surface area for electron transport chain proteins.

Cristae

Folds of the mitochondrial inner membrane that increase the surface area available for proteins involved in the electron transport chain.

Matrix

The fluid-filled space enclosed within the inner mitochondrial membrane where the citric acid cycle (Krebs cycle) takes place.

Aerobic Respiration

A series of chemical reactions that break down glucose in the presence of oxygen, yielding a high energy output of approximately $36$ to $38\,\text{ATP}$, carbon dioxide, and water.

Glycolysis

The first stage of cellular respiration occurring in the cytoplasm, where one six-carbon glucose molecule is broken down into two three-carbon pyruvate molecules, yielding a net $2\,\text{ATP}$ and $2\,\text{NADH}$.

Pyruvate (Pyruvic Acid)

The three-carbon end-product resulting from the breakdown of a six-carbon glucose molecule during glycolysis.

Acetyl-CoA (Acetyl Coenzyme A)

The two-carbon molecule formed in the mitochondrial matrix from pyruvate before entering the Krebs cycle.

Krebs Cycle (Citric Acid Cycle)

The second stage of aerobic respiration occurring in the mitochondrial matrix, where acetyl-CoA is broken down through enzyme-catalyzed reactions to release $\text{CO}_2$ and produce $2\,\text{ATP}$, $6\,\text{NADH}$, and $2\,\text{FADH}_2$ per glucose molecule.

Sir Hans Adolf Krebs

The British biochemist after whom the citric acid cycle (Krebs cycle) is named.

Electron Transport Chain (ETC)

The third stage of aerobic respiration that utilizes electrons transferred from $\text{NADH}$ and $\text{FADH}_2$ to produce the majority of cellular energy ($34\,\text{ATP}$), while oxygen acts as an electron acceptor to form water.

Anaerobic Respiration

A metabolic pathway occurring exclusively in the cytoplasm that releases energy from glucose in the absence of oxygen, yielding only $2\,\text{ATP}$ per glucose molecule.

Fermentation

A form of anaerobic respiration that breaks down pyruvic acid without using oxygen.

Alcoholic Fermentation

A type of fermentation occurring in plant and yeast cells that converts pyruvate into ethanol and carbon dioxide, enabling bread dough to rise and producing carbonation in beer and wine.

Lactic Acid Fermentation

A type of fermentation occurring in animal muscle cells during strenuous exercise when oxygen supplies are insufficient, converting pyruvic acid into lactic acid.

Light-Dependent Stage

The stage of photosynthesis that occurs in the thylakoid membranes of chloroplasts and requires light energy to synthesize energy-carrier molecules.

Light-Independent Stage (Dark Cycle)

The stage of photosynthesis that occurs in the stroma of chloroplasts, utilizing $\text{CO}_2$ to produce glucose without directly requiring light.