Biology Review Lecture – Core Vocabulary

A comprehensive set of vocabulary flashcards covering photosynthesis, cellular respiration, enzymes, energy, and cell division topics discussed in the lecture.

Photosynthesis

Process in which plants convert light energy, CO₂, and water into glucose (C₆H₁₂O₆) and O₂.

Cellular Respiration

Metabolic pathway that breaks down glucose to produce ATP; can be aerobic or anaerobic.

Enzyme

Protein catalyst that speeds up chemical reactions by lowering activation energy.

Activation Energy

Minimum amount of energy required to start a chemical reaction.

Entropy

Measure of disorder or randomness in a system.

ATP (Adenosine Triphosphate)

Primary energy currency of the cell; stores and releases energy in phosphate bonds.

Kinetic Energy

Energy of motion.

Potential Energy

Stored energy, sometimes called “stored” or “positional” energy.

Catalyzed Reaction

Chemical reaction sped up by an enzyme (or other catalyst).

Mitosis

Division of a eukaryotic nucleus into two genetically identical daughter nuclei.

Cytokinesis

Division of the cytoplasm that follows mitosis or meiosis.

Cleavage Furrow

Pinching-in of the plasma membrane during animal-cell cytokinesis.

Cell Plate

Structure that forms during plant-cell cytokinesis to create a new cell wall.

Meiosis

Reduction division that produces haploid gametes; involves two successive divisions.

Reduction Division

Another name for meiosis I; chromosome number is halved.

Competitive Inhibitor

Molecule that competes with the substrate for binding to the active site of an enzyme.

Light-Dependent Reaction

First stage of photosynthesis; occurs in thylakoid membranes and produces ATP, NADPH, and O₂.

Calvin Cycle

Light-independent reactions in the stroma that synthesize glucose from CO₂ using ATP and NADPH.

Stroma

Fluid interior of the chloroplast where the Calvin cycle occurs.

Stoma (Stomata)

Pore on the leaf underside that allows gas exchange of CO₂, O₂, and water vapor.

Thylakoid Membrane

Chloroplast membrane sac where light-dependent reactions occur.

Glycolysis

Anaerobic breakdown of glucose to pyruvate in the cytoplasm; produces 2 ATP.

Krebs Cycle (Citric Acid Cycle)

Aerobic pathway in the mitochondrial matrix that generates NADH, FADH₂, and 2 ATP.

Electron Transport Chain (ETC)

Series of proteins in the mitochondrial inner membrane that generate ~32 ATP via chemiosmosis.

Aerobic Respiration

Cellular respiration that requires oxygen and yields ~36 ATP per glucose.

Fermentation

Anaerobic process that regenerates NAD⁺ to keep glycolysis running; produces lactic acid or ethanol.

NAD⁺

Electron carrier required for glycolysis; reduced to NADH.

NADH

High-energy electron carrier produced in glycolysis and the Krebs cycle.

FADH₂

Electron carrier generated in the Krebs cycle and used in the ETC.

Pyruvic Acid (Pyruvate)

End product of glycolysis; converted to Acetyl-CoA when oxygen is present.

Acetyl-CoA

Two-carbon molecule entering the Krebs cycle; formed from pyruvate in the presence of O₂.

Chemiosmosis

ATP generation driven by a proton gradient across a membrane and ATP synthase.

ATP Synthase

Enzyme that makes ATP as protons flow down their gradient.

Binary Fission

Asexual cell division in prokaryotes producing two identical cells.

Interphase

Cell-cycle phase (G₁, S, G₂) where the cell grows, duplicates DNA, and prepares for division.

G₁ Phase

Interphase stage of cell growth and normal function before DNA replication.

S Phase

Interphase stage where DNA replication occurs.

G₂ Phase

Interphase stage for final preparations before mitosis.

Prophase

First stage of mitosis; chromosomes condense, spindle forms, nuclear envelope breaks down.

Metaphase

Mitosis phase where chromosomes align at the cell equator.

Anaphase

Mitosis phase where sister chromatids separate to opposite poles.

Telophase

Final mitosis phase; nuclear envelopes reform around chromosomes.

Homologous Chromosomes

Chromosome pair, one from each parent, similar in size and gene position.

Sister Chromatids

Identical copies of a chromosome connected by a centromere after DNA replication.

Crossing Over

Exchange of genetic material between homologous chromosomes in prophase I of meiosis.

Independent Assortment

Random orientation of homologous pairs during metaphase I; increases genetic variation.

Random Fertilization

Chance union of any sperm with any egg, adding to genetic diversity.

Diploid (2n)

Cell possessing two sets of chromosomes (human somatic cells: 46).

Haploid (n)

Cell with one set of chromosomes (human gametes: 23).

Zygote

Diploid cell formed by fusion of two haploid gametes at fertilization.

First Law of Thermodynamics

Energy cannot be created or destroyed, only transformed from one form to another.

Diffusion

Movement of molecules from a region of high concentration to low concentration.

O₂ (Oxygen)

Final electron acceptor in aerobic respiration; produced during photosynthesis.

CO₂ (Carbon Dioxide)

Gas taken up in photosynthesis and released in cellular respiration.