Cellular Respiration and Anaerobic Pathways

Comprehensive vocabulary flashcards covering the stages of cellular respiration (glycolysis, pyruvate oxidation, Krebs cycle, and ETC) and anaerobic fermentation pathways.

Substrate level Phosphorylation

The direct transfer of a Pi from another substrate to ADP.

Oxidative Phosphorylation

The primary means of producing ATP, where ATP is produced from energy acquired from a series of redox reactions.

Redox reactions

Reactions involving electron transfers that play a central role in energy creation; energy from electrons is used to acquire usable energy.

Glycolysis

The most ancient pathway for extracting energy from organic molecules, occurring in the cytosol without requiring $O_2$ or specialized organelles.

Hexokinase

The enzyme responsible for phosphorylation in Step 1 of glycolysis, converting Glucose into Glucose-6-phosphate ($G-6-P$) using 1 ATP.

Phosphoglucomutase

The enzyme used in Step 2 of glycolysis to rearrange $G-6-P$ into its isomer, fructose-6-phosphate ($F-6-P$), and also used in Step 8 to move phosphate from $C-3$ to $C-2$.

Phosphofructokinase

The enzyme in Step 3 of glycolysis that uses 1 ATP to attach a phosphate group to fructose-6-phosphate, producing Fructose-1,6-bisphosphate.

Aldose

The enzyme used in Step 4 of glycolysis to split Fructose-1,6-bisphosphate into glyceraldehyde-3-phosphate ($G3P$) and dihydroxyacetone phosphate ($DHAP$).

Triosephosphate dehydrogenase

The enzyme used in Step 6 of glycolysis to phosphorylate $G-3-P$ into 1,3-bisphosphoglycerate while reducing NAD to NADH.

Phosphoglycerate kinase

The enzyme used in Step 7 of glycolysis to transfer a phosphate group from 1,3-bisphosphoglycerate to ADP to produce ATP.

Enclose

The substance or enzyme that removes water in Step 9 of glycolysis as 2-Phosphoglycerate is converted to phosphoenclopyruvate ($PEP$).

Pyruvate kinase

The enzyme used in Step 10 of glycolysis to transfer the remaining phosphate group from $PEP$ to ADP, resulting in ATP and the final product, pyruvate.

Decarboxylation

The first step of pyruvate oxidation involving the removal of a carboxyl group to form $CO_2$.

Dehydrogenation

The second step of pyruvate oxidation where 2 electrons and two $H^+$ protons are transferred.

Acetyl-CoA

The product of pyruvate oxidation formed by a reaction with the Sulfur atom of CoA, which then enters the Citric Acid Cycle.

Oxaloacetate (OA)

The final product of the Krebs cycle that reacts with acetyl-CoA to form citrate and restart the cycle.

Succinate

A molecule in the Krebs cycle whose oxidation to fumarate transfers two electrons and protons to FAD to produce $FADH_2$.

Complex I (NADH dehydrogenase)

An enzyme in the electron transport chain that oxidizes NADH to $NAD^+$ by removing 2 electrons.

Ubiquinone (UQ)

An electron carrier that transports electrons from complex I and II to complex III, while also pumping $H^+$ into the intermembrane space.

Complex IV (Cytochrome oxidase)

A complex that transfers 4 electrons and $4H^+$ to an $O_2$ molecule to produce 2 water molecules.

ATP Synthase

A protein complex that harnesses the energy of $H^+$ ions moving down their gradient to create ATP.

Chemiosmosis

The process where a proton-motive force, produced by H moving down its concentration gradient, provides energy to ATP synthase to produce ATP.

Efficiency of Cellular Respiration

Calculated as 41\text{%} based on the production of $38$ ATP ($1178 \text{ kJ/mol}$) from the total $2870 \text{ kJ/mol}$ released by the oxidation of glucose.

Alcohol fermentation

An anaerobic pathway where ethanol is used to oxidize NADH to $NAD^+$ for glycolysis, producing 2 ethanol and $2CO_2$.

Lactate Fermentation

An anaerobic process where pyruvate is reduced to lactate by accepting electrons from NADH, thereby regenerating $NAD^+$ for glycolysis.