Carbohydrate Metabolism

Vocabulary practice flashcards covering carbohydrate metabolism pathways, including glycolysis, the Krebs cycle, the electron transport system, the pentose phosphate pathway, the Cori cycle, and hormonal/allosteric regulation.

Hexokinase

The enzyme responsible for converting cellular glucose to glucose-6-phosphate, marking the first step in glycogenesis or glycolysis.

Glycolysis

A pathway in the cytosol of the cell that converts glucose to pyruvate, requires $NAD^+$, produces $2\text{ ATP}$, and provides metabolic intermediates for triglyceride synthesis and nucleic acid synthesis.

Oxidative Respiration

The aerobic pathway that occurs with $O_2$ following glycolysis, yielding a net production of $34\text{ ATP}$.

Fermentation

The metabolic process that processes pyruvate without $O_2$ (anaerobic), producing either lactic acid or ethyl alcohol and $CO_2$.

Pyruvate Dehydrogenase Pathway

A pathway located in the mitochondrial matrix that links glycolysis to the Krebs cycle by converting pyruvate to acetyl-CoA.

Krebs Cycle

Also known as the Citric Acid Cycle or Tricarboxylic Acid Cycle; a cyclic pathway occurring in the mitochondrial matrix that generates energy precursors and provides intermediates for fatty acid synthesis, amino acid synthesis, and gluconeogenesis.

Electron Transport System (ETS)

A mitochondrial process involving the transfer of electrons from electron donors to electron acceptors, involving reactions such as $NADH \rightarrow NAD^+ + H^+$ and $FADH_2 \rightarrow FAD^+ + 2\,H^+$.

Pentose Phosphate Pathway

A metabolic pathway occurring in the cytosol that provides $5\text{ C}$ structures for nucleotide synthesis, $NADPH$ for fatty acid synthesis, and glyceraldehyde-3-phosphate.

Anaerobic Metabolism

A condition occurring under too little $O_2$ and excessive $NADH$ where $1\text{ glucose} \rightarrow 2\text{ pyruvate} \rightarrow 2\text{ lactate}$, causing lactic acid buildup, decreased pH, and muscle soreness.

Cori Cycle

A metabolic pathway where lactic acid travels from muscle cells via the blood to the liver, where it is converted from lactate to pyruvate to glucose, and glucose is returned to the cells.

Feedback Mechanism

A regulatory mechanism where concentrations of a compound act on enzymes or pathway components to modulate reactions, such as high concentrations of ATP and citrate limiting glycolysis while enhancing the pentose phosphate pathway.

Secondary Messengers

Phosphorylated compounds and signaling intermediaries—such as cAMP activated by adenylate cyclase in response to glucagon—that activate or deactivate key metabolic enzymes via protein kinase A (PKA).

Solely Ketogenic Amino Acids

Amino acids that feed strictly into ketogenic pathways (yielding acetyl-CoA or acetoacetyl-CoA), specifically leucine and lysine.

Glucogenic and Ketogenic Amino Acids

Amino acids that can be broken down into both glucogenic and ketogenic intermediates: isoleucine, phenylalanine, tyrosine, and tryptophan.