Cell Theory Course

Lesson 1 • Cell Size and Scale

Examines why cells are microscopic and how surface-area-to-volume ratio constrains cell size. Connects physical constraints to cellular function.

Lesson 2 • Prokaryotic Versus Eukaryotic Cells

Compares structural and functional differences between prokaryotes and eukaryotes. Establishes the cellular diversity that underpins all subsequent chapters.

Lesson 3 • The Three Tenets of Cell Theory

Defines and explains each tenet: all living things are made of cells, cells are the basic unit of life, and all cells arise from pre-existing cells.

Lesson 1 • Cytoskeleton and Cell Shape

Identifies microfilaments, intermediate filaments, and microtubules and their mechanical and transport roles. Connects cytoskeletal dynamics to cell movement and division.

Lesson 2 • Energy-Producing Organelles

Covers mitochondria and chloroplasts, their double-membrane structure, and endosymbiotic origin. Links organelle anatomy to ATP synthesis and photosynthesis.

Lesson 3 • Nucleus and Genetic Control Centre

Examines nuclear envelope structure, chromatin organisation, and the nucleolus. Connects nuclear architecture to gene expression and DNA replication.

Lesson 4 • Endomembrane System

Traces protein and lipid trafficking through the ER, Golgi apparatus, vesicles, and lysosomes. Demonstrates how compartmentalisation enables specialised biochemical environments.

Lesson 1 • Membrane Permeability and Selectivity

Analyses factors determining which molecules cross membranes freely or require assistance. Reinforces structure-function relationships established in the previous chapter.

Lesson 2 • Passive Transport Mechanisms

Covers simple diffusion, facilitated diffusion, and osmosis driven by concentration gradients. Establishes the thermodynamic basis for movement without energy input.

Lesson 3 • Active Transport Mechanisms

Examines primary and secondary active transport using ATP or electrochemical gradients. Connects energy expenditure to maintaining cellular homeostasis.

Lesson 1 • Introduction to Metabolism

Defines anabolism, catabolism, and the role of ATP as the universal energy currency. Establishes thermodynamic principles governing all cellular chemical reactions.

Lesson 2 • Photosynthesis: Light and Dark Reactions

Examines light-dependent reactions in the thylakoid and the Calvin cycle in the stroma. Connects photosynthesis to cellular respiration as complementary energy pathways.

Lesson 3 • Fermentation and Anaerobic Pathways

Describes lactic acid and alcoholic fermentation as strategies to regenerate NAD+ without oxygen. Contextualises anaerobic metabolism in muscle physiology and microbiology.

Lesson 4 • Cellular Respiration: Krebs Cycle and Oxidative Phosphorylation

Covers pyruvate oxidation, the citric acid cycle, and the electron transport chain. Connects NADH and FADH2 oxidation to the chemiosmotic synthesis of ATP.

Lesson 1 • Phases of the Cell Cycle

Defines G1, S, G2, and M phases and the events occurring in each. Establishes the temporal framework for understanding mitosis and meiosis.

Lesson 2 • DNA Repair Mechanisms

Covers mismatch repair, nucleotide excision repair, and base excision repair pathways. Connects repair fidelity to genome stability and cancer prevention.

Lesson 3 • Mechanisms of DNA Replication

Details the roles of helicase, primase, DNA polymerase, and ligase in semiconservative replication. Distinguishes leading-strand from lagging-strand synthesis.

Lesson 4 • Cell Cycle Checkpoints and Regulation

Examines G1/S, G2/M, and spindle assembly checkpoints controlled by cyclins and CDKs. Links checkpoint failure to uncontrolled proliferation and oncogenesis.

Lesson 1 • Sources of Genetic Variation

Identifies crossing over, independent assortment, and random fertilisation as variation sources. Links genetic diversity to evolutionary fitness and population genetics.

Lesson 2 • Meiosis II and Gamete Formation

Covers the second meiotic division separating sister chromatids and the differentiation of gametes. Connects meiosis II to fertilisation and restoration of diploidy.

Lesson 3 • Cytokinesis in Animal and Plant Cells

Compares cleavage furrow formation in animal cells with cell plate formation in plant cells. Demonstrates how cytoplasmic division completes the production of two daughter cells.

Lesson 4 • Mitosis: Stages and Chromosome Behaviour

Sequences prophase, metaphase, anaphase, and telophase events with chromosome and spindle dynamics. Connects mitosis to growth, repair, and asexual reproduction.

Lesson 1 • Transcription: DNA to mRNA

Covers promoter recognition, RNA polymerase elongation, and termination in prokaryotes and eukaryotes. Establishes mRNA as the informational intermediate between gene and protein.

Lesson 2 • Translation: Ribosome Function

Sequences initiation, elongation, and termination at the ribosome using A, P, and E sites. Connects ribosomal catalysis to polypeptide chain synthesis.

Lesson 3 • Gene Expression Regulation

Examines transcriptional, post-transcriptional, translational, and post-translational control mechanisms. Demonstrates how cells fine-tune protein output in response to environmental signals.

Lesson 4 • mRNA Processing in Eukaryotes

Describes 5' capping, 3' polyadenylation, and splicing of introns by the spliceosome. Connects pre-mRNA processing to mRNA stability, export, and translational efficiency.

Lesson 1 • Second Messengers and Signal Amplification

Examines cAMP, IP3, DAG, and calcium as intracellular amplifiers of extracellular signals. Demonstrates how a single ligand binding event triggers large-scale cellular responses.

Lesson 2 • Types of Cell Signalling

Distinguishes endocrine, paracrine, autocrine, and juxtacrine signalling by distance and mechanism. Establishes the conceptual framework for all subsequent signalling pathway analysis.

Lesson 3 • Receptor Classes and Ligand Binding

Covers G protein-coupled receptors, receptor tyrosine kinases, and ion channel receptors. Connects receptor structure to the specificity and speed of downstream responses.

Lesson 4 • MAPK and PI3K Signalling Pathways

Traces the Ras-MAPK and PI3K-Akt pathways from receptor activation to nuclear gene expression changes. Links these pathways to cell proliferation, survival, and cancer.