Fermentation and Cellular Energy (Glycolysis, Fermentation, and ATP Production)

A set of vocabulary flashcards covering key terms and definitions related to glycolysis, fermentation (lactic acid and alcoholic), and ATP production as described in the notes.

ATP

The cell’s energy currency; produced mainly during glycolysis, Krebs cycle, and electron transport chain. Glycolysis yields a net of 2 ATP per glucose.

Glycolysis

Cytoplasmic process that breaks glucose (6C) into two pyruvate (3C each), yielding a net 2 ATP and 2 NADH (and starting with 2 ATP).

Glucose

A six-carbon sugar that serves as the starting substrate for glycolysis.

Pyruvate

Three-carbon end product of glycolysis; fate depends on oxygen—enter mitochondria for aerobic respiration or be reduced during fermentation.

PGAL (phosphoglyceraldehyde)

Three-carbon intermediate formed during glycolysis; two PGAL molecules are produced per glucose.

NAD

Nicotinamide adenine dinucleotide; accepts hydrogen to become NADH during glycolysis; NAD+ is regenerated to keep glycolysis going.

NADH

Reduced form of NAD+; carries electrons to later stages or donates them to regenerate NAD+ during fermentation.

ADP

Adenosine diphosphate; combines with a phosphate to form ATP during glycolysis.

Phosphate group

High-energy phosphate moiety used to convert ADP to ATP during glycolysis.

Aerobic respiration

Pathway that requires oxygen; pyruvate enters mitochondria and undergoes Krebs cycle and the electron transport chain to produce ~36–38 ATP per glucose.

Krebs cycle

Mitochondrial cycle that processes pyruvate-derived intermediates to generate NADH, FADH2, CO2, and a small amount of ATP.

Electron transport chain

Mitochondrial protein system that uses NADH/FADH2 to drive ATP synthesis via oxidative phosphorylation.

Mitochondria

Cellular organelles where Krebs cycle and the electron transport chain take place; require oxygen.

Cytoplasm

Where glycolysis and fermentation occur; no mitochondria involved in these steps.

Anaerobic pathway (fermentation)

Pathways that occur without oxygen; regenerate NAD+ by converting pyruvate to lactic acid or ethanol; produce no net ATP themselves beyond glycolysis.

Lactic acid fermentation

Fermentation in cytoplasm where pyruvate is reduced to lactic acid by NADH; regenerates NAD+; used by animals and certain bacteria, contributing to sour flavors (e.g., yogurt, pickles, sourdough).

Ethyl alcohol / Ethanol

Alcohol produced during alcoholic fermentation (in yeast); CO2 is released; NAD+ regenerated; used in beverages and bread making.

Carbon dioxide (CO2)

Gas released during alcoholic fermentation (from pyruvate decarboxylation); helps bread dough rise.

NAD+ regeneration

Process of converting NADH back to NAD+ so glycolysis can continue in the absence of oxygen.

Fermentation ATP yield

Fermentation itself does not create net ATP; glycolysis yields 2 ATP per glucose, and NAD+ regeneration allows glycolysis to keep running.

Bread rising

CO2 produced by yeast during alcoholic fermentation inflates dough; ethanol is driven off by heat during baking.

Sourdough fermentation

Lactic acid fermentation by bacteria used in sourdough bread, contributing a sour flavor distinct from yeast-made breads.