Bio chem exam 16-18 vocab

Glycolysis

Conversion of one molecule of glucose into two molecules of pyruvate with net gain of 2 ATP

Pyruvate

three carbon product formed at the end of glycolysis

Hexokinase

Enzyme that phosphorylates glucose to glucose-6-phosphate, trapping it in the cell

glucose-6-phosphate (G6P)

phosphorylated glucose that cannot leave teh cell and is committed to metabolism

phosphoglucose isomerase

enzyme that converts glucose-6-phosphate to fructose-6-phosphate (reversible)

phosphofructokinase (PFK-1)

Allosteric enzyme that catalyzes an irreversible step and is the main regulatory point of glycolysis

Fructose-1,6-bisphosphate

6-carbon intermediate that is cleaved into 3-carbon molecules

glyceraldehyde-3-phosphate (GAP)

3-carbon intermediate that undergoes oxidation in glycolysis

NAD⁺ / NADH

and electron carrier that is reduced during glycolysis and must be regenerated

substrate-level phosphorylation

Formation of ATP directly from a phosphorylated intermediate

pyruvate kinase

enzyme that catalyzes the final irreversible step of glycolysis

fermentaion

ATP generating process where electrons are transferred between organic molecules to regenerate NAD⁺

Lactic acid fermentation

Conversion of pyruvate to lactate to regenerate NAD⁺ (in an no O₂ atmosophere)

Alcoholic fermentation

conversion of pyruvate to CO₂ and ethonal to regenerate NAD⁺ (in an anerobic enviorment)

Facultative anaerobe

Organism that can switch between aerobic metabolism and fermentation

Obligate anaerobe

organism that cannot survive in the presence of oxygen

Glucokinase

Form of hexokinase in the liver that is active at high glucose concentrations

fructose-2,6-bisphosphate

Regulatory molecule that actives glycolysis (activate glycolysis but inactivates glucoeogenesis)

gluconeogenesis

pathway that converts pyruvate into glucose

Pyruvate carboxylase

Enzyme that converts pyrvate to oxaloacetate using ATP and biotin

Biotin (vitamin B7)

Cofactor used in carboxylation reactions

Oxaloacetate (OOA) (gluconeogenesis)

Intermediate formed from pyruvate in; cannot cross the mitochondrial membrane directly to participate in processes like gluconeogenesis

malate shuttle

Systme that transports oxaloacetate equivalents out of the mitochondria

phosphoenolpyruvate carboxykinase (PEPCK)

Enzyment that converts oxacetate to phosphoenolpyruvate using GTP

Fructose-1,6-bisphosphatase

enzyme that bypasses PFK-1 in gluconeogensis

Glucose-6-phosphatase

Enzyme that converts glucose-6-phosphate to glucose in the liver

Gluconeogenic precursors

Non-carbohydrate sources used to make glucose (lactate, amino acids, glycerol).

Reciprocal regulation

When one pathway (glycolysis or gluconeogenesis) is active, the other is inhibited.

Fructose-2,6-bisphosphate

Key regulator that activates glycolysis and inhibits gluconeogenesis.

Insulin

Hormone that signals high blood glucose and inhibits gluconeogenesis.

Insulin resistance

Condition where insulin fails to inhibit gluconeogenesis (type 2 diabetes).

Cori cycle

Process where lactate from muscle is converted to glucose in the liver.

Glucose-alanine cycle

Cycle where alanine transports carbon and nitrogen from muscle to liver.

Substrate (futile) cycle

Simultaneous forward and reverse reactions that amplify metabolic signals.

Pentose phosphate pathway (PPP)

Pathway that generates NADPH and ribose-5-phosphate.

NADPH

Reducing equivalent used in biosynthesis and protection against oxidative damage.

Ribose-5-phosphate

Molecule used for nucleotide and nucleic acid synthesis.

Oxidative phase

Phase of PPP that produces NADPH.

Non-oxidative phase

Phase that rearranges sugars into glycolytic intermediates.

Acetyl-CoA

Two-carbon molecule that enters the citric acid cycle.

Oxidative decarboxylation

Reaction where CO₂ is removed and electrons are transferred.

Thiamine pyrophosphate (TPP)

Cofactor derived from vitamin B1 required for PDH.

Lipoic acid (lipoamide)

Cofactor that carries reaction intermediates within PDH.

Coenzyme A (CoA)

Molecule that carries acyl groups into metabolic pathways.

Dihydrolipoamide dehydrogenase

Enzyme that regenerates oxidized lipoamide.

Phosphorylation (Pyruvate Dehydrogenase regulation)

Inactivates Pyruvate Dehydrogenase.

Dephosphorylation (Pyruvate Dehydrogenase regulation)

Activates Pyruvate Dehydrogenase.

Beriberi

Disease caused by thiamine deficiency affecting PDH function.

Citric acid cycle (CAC)

Pathway that oxidizes acetyl-CoA to CO₂ and generates high-energy electrons.

Citrate synthase

Enzyme that combines acetyl-CoA and oxaloacetate to form citrate.

Aconitase

Enzyme that converts citrate to isocitrate.

Isocitrate dehydrogenase

Enzyme that produces NADH and CO₂ (key regulatory step).

α-Ketoglutarate dehydrogenase

Enzyme that produces NADH and is similar to Pyruvate Dehydrogenase (PDH).

Succinyl-CoA synthetase

Enzyme that generates ATP (GTP) by substrate-level phosphorylation.

Succinate dehydrogenase

Enzyme that produces FADH₂.

Fumarase

Enzyme that hydrates fumarate.

Malate dehydrogenase

Enzyme that regenerates oxaloacetate and produces NADH.

Oxaloacetate

Four-carbon molecule that combines with acetyl-CoA to continue the the citric acid cycle (it the staring and ending of the cycle).

NADH / FADH₂

Reduced electron carriers that feed into oxidative phosphorylation.

Anaplerotic reactions

Reactions that replenish citric acid cycle intermediates.

Glyoxylate cycle

Pathway (in plants, bacteria, and protists) that allows net synthesis of glucose from acetyl-CoA.