Metabolism, Glycolysis, and Nutrition Flashcards

Flashcards covering vocabulary and core concepts from metabolic pathways, nutrition, and glycolysis based on the lecture transcript.

Nutrition

The intake and utilization of food, which affects health, development, and performance.

Autotrophs

Organisms that can synthesize all their cellular constituents from simple molecules such as $H_2O$, $CO_2$, $NH_3$, and $H_2S$.

Chemolithotrophs

Organisms that obtain their energy through the oxidation of inorganic compounds such as $NH_3$, $H_2S$, or $Fe^{2+}$.

Photoautotrophs

Organisms that obtain free energy via photosynthesis, using light energy to produce carbohydrates, $(CH_2O)_n$.

Heterotrophs

Organisms that obtain free energy through the oxidation of organic compounds like carbohydrates, lipids, and proteins; they ultimately depend on autotrophs.

Obligate aerobes

Organisms that must use $O_2$ for nutrient breakdown.

Anaerobes

Organisms that employ oxidizing agents such as sulfate or nitrate instead of $O_2$.

Facultative anaerobes

Organisms such as E. coli that can grow in either the presence or the absence of $O_2$.

Obligate anaerobes

Organisms that are poisoned by the presence of $O_2$, with metabolisms resembling the earliest life-forms from more than 3.5 billion years ago.

Vitamins

Organic molecules that an animal is unable to synthesize and must therefore obtain from its diet.

Biotin (B7)

A water-soluble vitamin that acts as a biocytin coenzyme and mediates carboxylation reactions.

Cobalamin (B12)

A water-soluble vitamin involved in alkylation; deficiency causes Pernicious anemia.

Nicotinamide (Niacin; B3)

A vitamin component of coenzymes NAD+ and NADP+; deficiency causes Pellagra, characterized by dermatitis, diarrhea, and dementia.

Thiamine (B1)

A vitamin used in aldehyde transfer; deficiency leads to Beriberi.

Ascorbic acid (C)

A vitamin involved in hydroxylation; deficiency causes Scurvy.

Vitamin A

A fat-soluble vitamin necessary for vision; deficiency causes Night blindness.

Vitamin D

A fat-soluble vitamin necessary for $Ca^{2+}$ absorption; deficiency causes Rickets.

Metabolites

The reactants, intermediates, and products produced in metabolic pathways.

Catabolism

Degradative pathways in which complex metabolites are exergonically broken down into simpler products.

Anabolism

Biosynthetic pathways that use ATP and NADPH as free energy sources to form complex products.

Isozymes

Enzymes that catalyze the same reaction but are encoded by different genes and have different kinetic or regulatory properties.

Near-equilibrium reactions

Reactions with $\triangle G$ values close to zero that can be easily reversed by changing the ratio of products to reactants.

Irreversible reactions

Reactions functioning far from equilibrium with large negative $\triangle G$ values; they often serve as flux control points.

Steady state

A nonequilibrium state in living systems where materials and energy constantly enter and leave, maintaining intermediates at constant concentrations.

Allosteric control

Regulation of enzyme activity by effectors that bind to sites other than the active site, such as negative feedback regulation.

Substrate cycle

A set of opposing nonequilibrium reactions catalyzed by different enzymes (e.g., PFK and FBPase) that can produce a large fractional effect on pathway flux.

Adenosine triphosphate (ATP)

The universal 'high-energy' intermediate consisting of an adenosine moiety linked to three phosphoryl groups via one phosphoester and two phosphoanhydride bonds.

Phosphoryl group-transfer potential

The negative of the standard free energy change (-\triangle G^\ring) for the hydrolysis of a phosphorylated compound.

Substrate-level phosphorylation

The formation of ATP from ADP by the direct transfer of a phosphoryl group from a 'high-energy' compound.

Phosphagens

High-energy storage compounds such as phosphocreatine and phosphoarginine used to regenerate ATP in muscle and nerve cells.

Hexokinase

The enzyme for Reaction 1 of glycolysis that transfers a phosphoryl group from ATP to glucose to form glucose-6-phosphate (G6P).

Phosphoglucose isomerase (PGI)

The enzyme for Reaction 2 of glycolysis that converts G6P to fructose-6-phosphate (F6P) via an enediolate intermediate.

Phosphofructokinase (PFK)

The major flux-controlling enzyme of glycolysis that phosphorylates F6P to yield fructose-1,6-bisphosphate (FBP).

Aldolase

The enzyme for Reaction 4 of glycolysis that cleaves FBP into glyceraldehyde-3-phosphate (GAP) and dihydroxyacetone phosphate (DHAP).

Triose phosphate isomerase (TIM)

A 'catalytically perfect' enzyme that interconverts DHAP and GAP.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH)

The enzyme for Reaction 6 of glycolysis that oxidizes and phosphorylates GAP to form the high-energy intermediate 1,3-bisphosphoglycerate (1,3-BPG).

Phosphoglycerate kinase (PGK)

The enzyme for Reaction 7 of glycolysis that produces the first ATP by transferring a phosphoryl group from 1,3-BPG to ADP.

Phosphoglycerate mutase (PGM)

The enzyme for Reaction 8 of glycolysis that interconverts 3-phosphoglycerate (3PG) and 2-phosphoglycerate (2PG).

Enolase

The enzyme for Reaction 9 of glycolysis that dehydrates 2PG to form the high-energy compound phosphoenolpyruvate (PEP).

Pyruvate kinase (PK)

The enzyme for Reaction 10 of glycolysis that couples PEP cleavage to ATP synthesis, forming pyruvate.

Pyruvate dehydrogenase complex

A multienzyme complex (comprising E1, E2, and E3) that catalyzes the oxidative decarboxylation of pyruvate to form acetyl-CoA.

Lipoamide

A prosthetic group consisting of lipoic acid linked to a Lys residue on E2; it acts as a 'swinging arm' to transfer reaction intermediates between active sites.