What's in General Biology I: the 16 units, in order

General Biology I is the first half of the two-semester majors sequence: chemistry, cells, energy, genetics and gene expression. Encodr's free General Biology I course covers it in 16 units, 86 chapters and 1,390 study cards, plus a short note card at the start of every chapter with its key terms. It follows OpenStax Biology 2e chapters 1-17, the most widely adopted free intro biology text, and is cross-checked against the C-ID BIOL 135S transfer descriptor and AP Biology units 1-6. Every card is credited to one of 200 sources.

Here is what each unit covers, in the order the course teaches it.

Units 1-3: the chemistry of life (OpenStax ch 1-3)

Unit 1, The Science of Biology (4 chapters). The properties and levels of organization of life, the scientific method, experimental design (independent and dependent variables, positive and negative controls, replication), and the unifying themes of biology.

Unit 2, Chemistry for Biology (6 chapters). Atoms, isotopes and radioisotopes, ionic and covalent bonds, hydrogen bonds and van der Waals interactions, the properties of water, pH, acids, bases and buffers, and carbon with its functional groups. The pH chapter has calculation cards: a solution at pH 4 has 10^3 = 1,000 times more H+ than one at pH 7.

Unit 3, Biological Macromolecules (5 chapters). Dehydration synthesis and hydrolysis, then carbohydrates, lipids, proteins (with the four levels of structure) and nucleic acids.

Units 4-6: the cell (OpenStax ch 4-6)

Unit 4, Cell Structure (7 chapters). Cell theory and microscopy (with magnification and surface-area-to-volume math), prokaryotic cells, eukaryotic organelles, the endomembrane system, the cytoskeleton, cell junctions and the extracellular matrix, and the evidence for endosymbiosis.

Unit 5, Membranes and Transport (5 chapters). The fluid mosaic model, diffusion and facilitated diffusion, osmosis and tonicity, active transport (including the sodium-potassium pump), and endocytosis and exocytosis.

Unit 6, Energy, Metabolism and Enzymes (6 chapters). Metabolic pathways, the laws of thermodynamics, free energy (exergonic and endergonic reactions), ATP and energy coupling, enzymes and activation energy, and enzyme regulation and inhibition.

Units 7-9: energy and signals (OpenStax ch 7-9)

Unit 7, Cellular Respiration (6 chapters). Redox and the electron carriers NAD+ and FAD, glycolysis, pyruvate oxidation and the citric acid cycle, oxidative phosphorylation and chemiosmosis, fermentation, and how respiration connects to other pathways. This is the biggest unit, tied with Cell Structure and Gene Expression.

Unit 8, Photosynthesis (5 chapters). The chloroplast, light and pigments, the light-dependent reactions, the Calvin cycle, and photorespiration with the C4 and CAM workarounds. Cellular respiration vs photosynthesis, side by side compares units 7 and 8 directly.

Unit 9, Cell Communication (4 chapters). Signaling types and molecules, receptors, signal transduction and second messengers, and cellular responses, including signaling in single-celled organisms.

Units 10-13: division and inheritance (OpenStax ch 10-13)

Unit 10, The Cell Cycle and Mitosis (6 chapters). Chromosomes and chromatin, interphase and the phases of mitosis, cytokinesis, cell-cycle checkpoints, cancer as a loss of cell-cycle control, and binary fission in prokaryotes.

Unit 11, Meiosis and Sexual Reproduction (4 chapters). Meiosis I and II, crossing over and independent assortment, mitosis vs meiosis, and the three types of sexual life cycles.

Unit 12, Mendelian Genetics (6 chapters). Mendel's pea experiments, segregation and independent assortment, Punnett squares and test crosses, the product and sum rules of probability, extensions (incomplete dominance, codominance, multiple alleles, epistasis), and a short chi-square chapter. Chi-square is not in the OpenStax text, but AP Biology and many labs use it, so it is marked as lab-dependent. Punnett squares: monohybrid and dihybrid crosses works through this unit's math, and the Punnett square calculator checks any one- or two-gene cross.

Unit 13, Chromosomes and Inheritance (4 chapters). The chromosomal theory of inheritance, linkage and recombination mapping (1 percent recombination = 1 map unit), sex-linked inheritance and pedigrees, and disorders of chromosome number and structure, including nondisjunction.

Units 14-16: molecular biology (OpenStax ch 14-17)

Unit 14, DNA Structure and Replication (6 chapters). The experiments that identified DNA as the genetic material (Griffith, Avery, Hershey-Chase, Chargaff, Franklin, Watson and Crick, Meselson-Stahl), DNA structure, replication in prokaryotes and eukaryotes, telomeres, and DNA repair.

Unit 15, Gene Expression (7 chapters). The genetic code and the central dogma, transcription, RNA processing, translation, prokaryotic gene regulation (the lac and trp operons), and eukaryotic regulation at the epigenetic, transcriptional, post-transcriptional and translational levels. It spans OpenStax chapters 15 and 16.

Unit 16, Biotechnology and Genomics (5 chapters). DNA cloning and recombinant DNA, PCR and gel electrophoresis, CRISPR and gene editing, genome mapping and sequencing, and genomics and proteomics with their applications.

How the course is built

• Sized by class time. Each unit's share of cards matches its share of a typical 15-week semester, so Cell Structure, Cellular Respiration and Gene Expression (1.5 weeks each) are the largest units and Unit 1 and Unit 9 (half a week each) are the smallest.
• Taught in order. Units run 1 to 16 and chapters build on each other, so a card never leans on a term a later chapter introduces.
• Math is recomputed. Every calculation card (pH, magnification, Punnett ratios, probability, chi-square, map distances, PCR doubling) was checked by a script, not by hand.
• Mixed card types. Question-and-answer, multiple choice, fill-in-the-blank, typed calculations, true/false, and ordering cards for real sequences such as the phases of mitosis and the steps of glycolysis.

If your syllabus covers evolution, diversity, physiology and ecology instead, that is the second semester: see what's in General Biology II. The first-year science courses overview lists all six courses, and how to study for a general biology exam covers how to use a course like this before a test. Units 1-3 lean on bonding, pH and molecules, so if you're taking chemistry at the same time, what's in General Chemistry I shows where those topics land in that course.

The General Biology I course is free on Encodr.