Metabolism, Cellular Respiration & DNA Structure – Vocabulary Review

A comprehensive set of vocabulary flashcards covering key terms from metabolism, cellular respiration, and DNA structure/replication lecture notes.

Metabolic Pathway

A coordinated series of enzyme-catalyzed chemical reactions occurring in a cell.

Catabolic Reaction (Catabolism)

The breakdown of large molecules into smaller ones, releasing energy that can be captured in energy intermediates.

Anabolic Reaction (Anabolism)

The synthesis of larger molecules from smaller precursors; requires an input of energy.

Energy Intermediate

A molecule such as ATP or NADH that temporarily stores energy to drive endergonic reactions.

Redox Reaction

A reaction involving the transfer of electrons; one molecule is oxidized while another is reduced.

Oxidation

Removal of one or more electrons from an atom or molecule.

Reduction

Addition of one or more electrons to an atom or molecule.

Substrate-Level Phosphorylation

Direct transfer of a phosphate group from an organic molecule to ADP to form ATP.

Chemiosmosis

Use of an ion electrochemical gradient to drive ATP synthesis from ADP and Pi.

Gene Regulation (Metabolic)

Turning genes on or off to increase or decrease enzyme production for metabolic pathways.

Cell Signaling Regulation

Adjustment of metabolic pathways in response to external or internal cellular signals.

Metabolic Cycle

A biochemical cycle where molecules enter and leave but key intermediates are regenerated each turn.

Glycolysis

Pathway that splits glucose into two pyruvate molecules, producing 2 ATP and 2 NADH.

Pyruvate Breakdown (Pyruvate Oxidation)

Conversion of pyruvate into an acetyl group and CO₂, generating NADH; acetyl group becomes Acetyl-CoA.

Citric Acid Cycle (Krebs Cycle)

Metabolic cycle that oxidizes Acetyl-CoA to CO₂, producing ATP (or GTP), NADH, and FADH₂.

Oxidative Phosphorylation

Process in which the ETC and ATP synthase use energy from NADH/FADH₂ electrons to make most cellular ATP.

Electron Transport Chain (ETC)

Series of membrane protein complexes (I–IV) that pass electrons and pump H⁺ to build the proton gradient.

Proton Motive Force

Electrochemical gradient of H⁺ across the inner mitochondrial membrane that drives ATP synthesis.

ATP Synthase

Rotary enzyme that uses proton flow to convert ADP + Pi into ATP.

Acetyl-CoA

Two-carbon acetyl group attached to coenzyme A; entry molecule for the citric acid cycle.

NADH

Reduced electron carrier that donates electrons to Complex I of the ETC.

FADH₂

Reduced electron carrier that donates electrons to Complex II of the ETC.

Oxaloacetate

Four-carbon molecule that combines with Acetyl-CoA to begin the citric acid cycle and is regenerated at the end.

Citrate

Six-carbon molecule formed from Acetyl-CoA and oxaloacetate at the start of the citric acid cycle.

α-Ketoglutarate

Five-carbon intermediate of the citric acid cycle produced from isocitrate oxidation.

Succinyl-CoA

Four-carbon intermediate of the citric acid cycle that yields GTP/ATP when converted to succinate.

GTP

Guanosine triphosphate; energy currency equivalent to ATP produced in the citric acid cycle.

Complex I (NADH Dehydrogenase)

ETC complex that accepts electrons from NADH and pumps H⁺ into the intermembrane space.

Complex II (Succinate Reductase)

ETC complex that accepts electrons from FADH₂; does not pump protons.

Ubiquinone (Coenzyme Q)

Mobile lipid carrier that transfers electrons from Complexes I/II to Complex III.

Cytochrome b-c₁ (Complex III)

ETC complex that passes electrons to cytochrome c while pumping H⁺.

Cytochrome c

Small peripheral protein that shuttles electrons from Complex III to Complex IV.

Cytochrome Oxidase (Complex IV)

Final ETC complex that transfers electrons to O₂, forming water and pumping additional H⁺.

Aerobic Respiration

Cellular respiration using O₂ as the final electron acceptor; yields ~30–34 ATP per glucose.

Anaerobic Respiration

Respiration using an alternative final electron acceptor such as NO₃⁻; less efficient than aerobic.

Fermentation

Anaerobic process in which glycolysis continues and NAD⁺ is regenerated without an ETC, producing 2 ATP per glucose.

Lactic Acid Fermentation

Fermentation pathway converting pyruvate to lactate, common in muscle cells.

Alcohol Fermentation

Fermentation pathway in yeast converting pyruvate to ethanol and CO₂.

F₀ Subunit (ATP Synthase)

Membrane-embedded portion of ATP synthase that forms the H⁺ channel.

F₁ Subunit (ATP Synthase)

Matrix-exposed catalytic portion of ATP synthase that synthesizes ATP.

Open, Loose, Tight Conformations

Three repeating shapes of ATP synthase active sites that bind substrates, hold them, then synthesize and release ATP.

Glycogen

Storage polysaccharide of glucose in animals; can be broken down to fuel glycolysis.

Deamination

Removal of an amino group from an amino acid so its carbon skeleton can enter cellular respiration.

β-Oxidation

Stepwise breakdown of fatty acids into Acetyl-CoA units for entry into the citric acid cycle.

Information (Genetic Property)

Requirement that genetic material contains instructions to build an organism.

Replication (Genetic Property)

Ability of genetic material to be accurately copied during cell division.

Transmission (Genetic Property)

Genetic material must be passed from parents to offspring and from cell to cell.

Variation (Genetic Property)

Genetic material must account for heritable differences among organisms.

Nucleotide

Monomer of DNA/RNA composed of a phosphate group, five-carbon sugar, and nitrogenous base.

Phosphodiester Bond

Covalent linkage between the 5′ phosphate of one nucleotide and the 3′ hydroxyl of the next.

Antiparallel Strands

Orientation of the two DNA strands running in opposite 5′→3′ directions.

Chargaff’s Rules

Principle that in DNA the amount of A equals T and the amount of G equals C.

Major and Minor Grooves

Unequal spaces in the DNA double helix where proteins can bind to specific base sequences.

Rosalind Franklin

Scientist whose X-ray diffraction images (Photo 51) revealed DNA’s helical structure.

Erwin Chargaff

Biochemist who discovered base-pairing equivalence, providing clues to DNA structure.

Watson & Crick

Researchers who proposed the double-helix model of DNA in 1953 using Franklin’s data and Chargaff’s rules.