Biochemistry Exam Review: Glycolysis, Citric Acid Cycle, Oxidative Phosphorylation, and Photosynthesis

A complete set of 39 vocabulary flashcards covering metabolic pathways, enzyme functions, stoichiometry, electron transport complexes, and photophosphorylation.

Phosphoryl-transfer potential ranking

The relative thermodynamic tendency to donate a phosphate group, ranked from highest to lowest as $\text{PEP} > \text{ATP} > \text{F6P}$.

High-energy phosphoanhydride bonds in ATP

The chemical bonds connecting the phosphate groups in ATP, of which ATP contains exactly $2$.

$$\text{NAD}^+$$

A metabolic coenzyme that accepts $2$ electrons and $1$ proton ($\text{NAD}^+ \rightarrow \text{NADH}$).

FAD

A metabolic coenzyme that accepts $2$ electrons and $2$ protons ($\text{FAD} \rightarrow \text{FADH}_2$).

Mutase

An enzyme that moves a phosphate group within the same molecule.

Isomerase

An enzyme that rearranges atoms within a molecule to form an isomer.

Epimerase

An enzyme that changes the chemical configuration at one chiral carbon.

GAP dehydrogenase reaction

Step $6$ of glycolysis ($\text{GAP} \rightarrow \text{1,3-BPG}$) that produces $\text{NADH}$.

Glycolysis Step 7

The glycolytic reaction that converts $\text{1,3-BPG}$ to $\text{3-PG}$ and produces ATP by substrate-level phosphorylation.

Glycolysis Step 9

The glycolytic reaction that converts $\text{2-PG}$ to PEP and releases $H_2O$.

Succinate to fumarate reaction

The reversible reaction within the citric acid cycle (CAC) catalyzed by succinate dehydrogenase.

Irreversible CAC reactions

The three non-reversible citric acid cycle reactions, catalyzed by citrate synthase, isocitrate dehydrogenase, and $\alpha$-ketoglutarate dehydrogenase.

Glycogen phosphorylase

The enzyme involved in glycogen breakdown that releases glucose 1-phosphate (G1P), but is not involved in glycogen synthesis.

Glycogenin

A protein enzyme that initiates glycogen synthesis by creating a glucose primer.

Glycogen synthase

An enzyme that adds glucose from UDP-glucose to the nonreducing ends of glycogen.

Total NADH yield per glucose

Exactly $10$ molecules of $\text{NADH}$ produced from one glucose molecule through glycolysis, PDC, and CAC.

Pathway NADH yields per glucose

The specific amounts of $\text{NADH}$ produced per glucose across stages: $2$ from glycolysis, $2$ from PDC, and $6$ from CAC.

Complex II

The mitochondrial ETC complex that transfers electrons from $\text{FADH}_2$ but is not involved in transferring electrons from $\text{NADH}$.

NADH-associated ETC complexes

Mitochondrial ETC Complexes I, III, and IV, which transfer electrons originating from $\text{NADH}$.

$\text{FADH}_2$-associated ETC complexes

Mitochondrial ETC Complexes II, III, and IV, which transfer electrons originating from $\text{FADH}_2$.

Coenzyme Q

A mitochondrial ETC carrier that carries $2$ electrons when fully reduced ($\text{Q} \rightarrow \text{QH}_2$).

Cytochrome c

A mitochondrial ETC carrier that transfers exactly $1$ electron.

Flavin mononucleotide (FMN)

A mitochondrial ETC carrier capable of accepting $2$ electrons ($\text{FMN} \rightarrow \text{FMNH}_2$).

Proton pumping per NADH

A total of $10\,H^+$ pumped across the inner mitochondrial membrane during ETC ($4\,H^+$ by Complex I, $4\,H^+$ by Complex III, and $2\,H^+$ by Complex IV).

Proton pumping per $\text{FADH}_2$

A total of $6\,H^+$ pumped across the inner mitochondrial membrane during ETC ($4\,H^+$ by Complex III and $2\,H^+$ by Complex IV).

Water production in ETC

Exactly $1$ molecule of $H_2O$ generated per $2$ electrons transferred to $O_2$.

ATP yield per cofactor

The stoichiometric yield of ATP generated per coenzyme: $2.5$ ATP per $\text{NADH}$ and $1.5$ ATP per $\text{FADH}_2$.

Proton gradient

The electrochemical gradient generated by the ETC that provides the energy driving ATP synthesis by mitochondrial ATP synthase.

$F_0$ subunit of ATP synthase

The ATP synthase subunit that forms the proton channel located in the inner mitochondrial membrane.

$F_1$ subunit of ATP synthase

The catalytic subunit of ATP synthase that synthesizes ATP from ADP and $\text{P}_i$.

Gamma ($\gamma$) subunit of ATP synthase

The subunit of ATP synthase that rotates and alters the conformation of the $F_1$ subunit to drive ATP synthesis.

Photon requirement per electron

Exactly $2$ photons required per electron transferred during noncyclic photosynthetic light reactions.

Products of the light reaction per $O_2$

The chemical output generated per $O_2$ produced: $2$ NADPH, $3$ ATP, and $1$ $O_2$.

Photon requirement per $O_2$

Exactly $8$ photons required to produce $1$ molecule of $O_2$ in the photosynthetic light reaction.

Citric acid cycle dehydrogenases

The four dehydrogenase enzymes of the CAC: isocitrate dehydrogenase, $\alpha$-ketoglutarate dehydrogenase, succinate dehydrogenase, and malate dehydrogenase.

Succinate dehydrogenase

The specific CAC dehydrogenase that produces $\text{FADH}_2$ instead of $\text{NADH}$.

NADH-producing CAC dehydrogenases

The three CAC enzymes that reduce $\text{NAD}^+$ to produce $\text{NADH}$: isocitrate dehydrogenase, $\alpha$-ketoglutarate dehydrogenase, and malate dehydrogenase.

Direct products of pyruvate

The five direct downstream molecules formed from pyruvate: lactate, acetaldehyde, oxaloacetate, acetyl-CoA, and alanine.

Lactic acid fermentation

The metabolic pathway where pyruvate is converted to lactate while $\text{NADH}$ is oxidized to $\text{NAD}^+$.