HBio Unit 4: Cells and Energy

Vocabulary flashcards covering the stages, equations, structures, and products of cellular respiration and fermentation from HBio Unit 4.

Cellular Respiration

The cellular process where cells make their own energy ($\text{ATP}$) to run all cell processes, with the overall reaction: $\text{Glucose} + \text{Oxygen} \rightarrow \text{Carbon Dioxide} + \text{Water} + \text{ATP}$.

Adenosine Triphosphate (ATP)

The primary energy-storing molecule for the cell, composed of adenine, ribose, and three phosphate groups, whose stored energy is released when phosphate bonds break.

ATP/ADP Cycle

The reaction cycle in which $1$ phosphate bond of $\text{ATP}$ is broken, releasing energy and producing $\text{ADP}$ plus an inorganic phosphate.

Adenosine Diphosphate (ADP)

The molecule formed alongside an inorganic phosphate and released energy when a phosphate bond in $\text{ATP}$ is broken.

Glycolysis

The first step of cellular respiration occurring in the cytoplasm, in which $2\text{ ATP}$ are used to split a $6$-carbon glucose molecule into $2$ three-carbon pyruvates, yielding $4\text{ ATP}$ total ($2\text{ net ATP}$) and $2\text{ NADH}$.

Pyruvate

A $3$-carbon sugar produced at the end of glycolysis from splitting glucose.

Aerobic Respiration

The pathway cellular respiration takes if oxygen is present after glycolysis, proceeding through the Krebs cycle and the electron transport chain ($\text{ETC}$).

Krebs Cycle

The second step of aerobic cellular respiration (also known as the Citric Acid Cycle) occurring in the mitochondrial matrix, converting $2$ pyruvates into acetyl-CoA, and producing carbon dioxide ($\text{CO}_2$), $2\text{ ATP}$, $\text{NADH}$, and $\text{FADH}_2$.

Acetyl-CoA

The intermediate molecule formed from pyruvic acid before entering the main reactions of the Krebs cycle.

NADH and FADH2

Electron carrier molecules formed during glycolysis and the Krebs cycle that transport electrons to the electron transport chain.

Electron Transport Chain (ETC)

The third step of cellular respiration occurring across the cristae of the mitochondria, utilizing oxygen, $\text{NADH}$, and $\text{FADH}_2$ to produce water and $32\text{ ATP}$.

Mitochondria

The double-membrane organelle that produces cellular energy during aerobic respiration, featuring inner folds called cristae and an internal fluid space called the matrix.

Cristae

The folded inner membrane structures of the mitochondria where the electron transport chain ($\text{ETC}$) occurs.

Matrix

The internal fluid-filled space within the inner membrane of the mitochondria where the Krebs cycle takes place.

Anaerobic Respiration (Fermentation)

The metabolic process occurring in the cytoplasm after glycolysis when oxygen is not present, utilizing pyruvate and $\text{NADH}$ to produce either lactic acid or ethanol.

Lactic Acid

The product generated from pyruvate during anaerobic fermentation in humans when oxygen is absent.

Ethanol

The product generated from pyruvate during anaerobic fermentation in bacteria and yeast when oxygen is absent.