Biochemistry and Metabolic Pathways Review

Vocabulary practice flashcards covering cellular metabolism, glycolysis, the Krebs cycle, the electron transport chain, fatty acid oxidation, lipoproteins, amino acid structure, and nucleic acid biochemistry.

Metabolism

The complete set of biochemical reactions occurring within a living cell.

Anabolism

A bottom-up metabolic pathway in which energy is utilized to build complex molecules from smaller, simpler molecules.

Catabolism

A top-down metabolic pathway in which larger, complex molecules are broken down into smaller or simple molecules, resulting in the release of energy.

Adenosine Triphosphate (ATP)

A cellular energy currency molecule composed of the nitrogenous base adenine, a sugar, and three phosphate groups.

Exergonic Reaction

A spontaneous biochemical reaction characterized by a negative change in Gibbs free energy ($\Delta G < 0$), such as the phosphorylation of glucose by ATP ($\Delta G = -16.7\,\text{kJ/mol}$).

Glycolysis

A catabolic pathway in the cytoplasm that breaks down one $6$-carbon glucose molecule into two $3$-carbon pyruvate molecules, netting $2$ ATP and $2$ NADH.

Pyruvate Dehydrogenase

The enzyme responsible for converting pyruvate into acetyl-CoA.

Substrate-Level Phosphorylation and Ionic Gradient

The two primary mechanisms utilized by biological systems to generate energy in the form of ATP.

Krebs Cycle

A core aerobic metabolic cycle in cellular respiration where acetyl-CoA combines with oxaloacetate to form citrate, generating $3$ NADH per turn.

Aconitase

An enzyme that accelerates the conversion of citrate to isocitrate in the Krebs cycle, which is competitively inhibited by fluoroacetate.

Complex II

A component of the electron transport chain (ETC) located in the inner mitochondrial membrane that does not generate or pump protons across the membrane.

Alpha Carbon (Fatty Acid)

The second carbon in a fatty acid chain, directly attached to the carbonyl carbon.

Beta Carbon (Fatty Acid)

The third carbon atom in a fatty acid chain.

Palmitic Acid

A $16$-carbon saturated fatty acid with the molecular formula $C_{16}H_{32}O_2$ and chemical formula $CH_3(CH_2)_{14}COOH$.

Lipase

The enzyme responsible for cleaving free fatty acids from triglycerides.

Beta-Oxidation

The metabolic process that breaks down fatty acid chains two carbons at a time, generating energy carriers like NADH and acetyl-CoA.

Acetoacetate

The initial ketone body synthesized during ketoacidosis.

Chylomicron

A lipoprotein responsible for packaging and solubilizing exogenous triglycerides.

High-Density Lipoprotein (HDL)

A lipoprotein specialized in solubilizing and transporting cholesterol.

Carnitine Palmitoyltransferase I (CPTI)

An enzyme located in the outer mitochondrial membrane that facilitates fatty acid transport into the mitochondria.

Type I Dyslipidemia

A lipid disorder characterized by the excessive buildup of triglycerides (TG).

Type IV Dyslipidemia

A metabolic lipid disorder caused by the overproduction of very-low-density lipoproteins (VLDL).

Abetalipoproteinemia

A medical condition marked by a failure in cellular lipid transport.

Nonessential Amino Acids

Amino acids that can be synthesized de novo by the human body.

Zwitterion

A dipolar form of an amino acid containing a negative charge at the C-terminus and a positive charge at the N-terminus.

Peptide Bond

The covalent chemical bond linking amino acid monomers together to build proteins.

Cysteine

A sulfur-containing amino acid with a side chain capable of forming covalent disulfide bonds.

Nucleotide

An acidic molecular subunit consisting of a pentose sugar, a nitrogenous base, and one or more phosphate groups.

Nucleoside

A molecule consisting of a nitrogenous base joined to a pentose sugar via a glycosidic bond, lacking a phosphate group.

Purines

The larger two-ring class of nitrogenous bases found in nucleic acids, comprising adenine and guanine.

Pyrimidines

The smaller single-ring class of nitrogenous bases found in nucleic acids, comprising cytosine, thymine, and uracil.

Gout

A metabolic disorder caused by aberrant purine catabolism, leading to elevated uric acid and sodium urate crystal deposition.

Arachidonic Acid

A $20$-carbon polyunsaturated omega-6 fatty acid ($C20:4\,\Delta^{5,8,11,14}$) that serves as a precursor for leukotrienes and prostaglandins.

Thromboxane A2 (TXA2)

An eicosanoid derivative whose elevation causes vasoconstriction.

Prostaglandin E2 (PGE2)

A prostaglandin signaling molecule that modulates body temperature regulation within the hypothalamus.