Cell Biology

Explore the cell as the fundamental building block of life, its organelles such as mitochondria and endoplasmic reticulum, and molecular machinery that sustain homeostasis, replication, and intercellular communication.

Explore the cell theory, revealing that all living things are made of cells, cells are the smallest working units, and all cells arise from cell division.

Explore the differences between multicellular and unicellular organisms, highlighting cellular complexity, specialization, interdependence, and adaptive diversity across plants, animals, fungi, bacteria, and protists.

Discover how light microscopy uses visible light, refraction, and glass lenses to magnify and resolve cellular structures, revealing organelles, tissues, and biomolecules with a resolution of about two microns.

Explore the principles and capabilities of electron microscopy, from the electron beam's ability to reveal atomic-scale detail to practical resolutions around two nanometer, and compare transmission and scanning electron microscopes.

Explore how scanning electron microscopy reveals high-resolution, three-dimensional images of cell surfaces by coating samples with a conductive film, scanning with an electron beam, and collecting secondary electrons for topography.

Discover how transmission electron microscopy uses a beam and electromagnets to image the internal ultrastructure of cells. See how heavy-metal staining enhances contrast for detailed two-dimensional views of organelles.

Contrast prokaryotic and eukaryotic cells by nucleus presence, organelles, and complexity, with examples from bacteria, archaea, plants, and animals.

Explore prokaryotic cell structure, from the cell wall and membrane to cytoplasm, nucleoid, ribosomes, and plasmids. Discover how flagella, pili, and genetic elements support movement, adhesion, and adaptation.

Examine the eukaryotic cell membrane, a phospholipid bilayer that regulates transport, supports signaling and adhesion, and mediates endocytosis and exocytosis within the fluid mosaic model.

Explore the structure and function of the eukaryotic cell wall, a rigid protective layer around the cell membrane made of cellulose, chitin, or peptidoglycan, providing support, protection, and environmental interactions.

Explore the nucleus as the cell's command center, a double-membrane organelle with pores, housing DNA and chromosomes, regulating gene expression, and guiding RNA synthesis in the nucleolus.

Explore how the cytoplasm surrounds the nucleus to provide structural support, host metabolic reactions, enable intracellular transport, coordinate signaling, store nutrients, and dynamically sustain cellular homeostasis.

Explore the endoplasmic reticulum in eukaryotic cells, detailing the rough ER's protein synthesis with ribosomes and the smooth ER's lipid synthesis and detoxification, plus its role in folding and secretion.

Discover how eukaryotic ribosomes, with large and small subunits, translate mRNA into proteins, free in the cytoplasm or bound to the rough endoplasmic reticulum, with regulation by nutrients and stress.

Explore mitochondria as the powerhouse of eukaryotic cells, detailing their double membrane, cristae, and matrix, and tracing atp production, citric acid cycle, fatty acid oxidation, calcium regulation, and apoptosis.

Explore the Golgi bodies as the central hub for protein modification, sorting, and secretion. Understand the cis, medial, and trans-golgi network regions and anterograde and retrograde transport.

Explore the lysosome as the cell’s recycling center, with a lipid bilayer membrane and acidic pH, detailing autophagy, phagolysosomes, apoptosis, and waste management via hydrolytic enzymes.

Explore the structure and diverse functions of vacuoles in eukaryotic cells, including tonoplast-enclosed compartments in plants, for storage, waste management, ion balance, detoxification, and defense.

Explore chloroplast structure, including outer and inner membranes, thylakoids, grana, and stroma, and their roles in photosynthesis, carbon fixation, and oxygen production.

Explore how microtubules assemble from alpha and beta tubulin, grow with plus and minus ends from organizing centers, and drive cellular shape, transport, division, and cilia-based movement.

Explore cell junctions that enable communication, adhesion, and mechanical strength across tissues, including tight junctions, adherens junctions, gap junctions, and desmosomes, with roles in signaling and tissue integrity.

Explore how cell division drives growth, development, tissue repair, and reproduction, and how interphase prepares the cell for DNA replication and division through G1, S, and G2.

Explore mitosis and meiosis, the two cell divisions. Mitosis supports tissue growth and maintenance in somatic and germinal cells, while meiosis forms gametes and drives genetic variation for sexual reproduction.

Mitosis drives cell division, producing two genetically identical daughter cells by distributing replicated chromosomes through prophase, metaphase, anaphase, telophase, and cytokinesis, ensuring growth, development, and tissue repair.

Explore meiosis I and II, including prophase I, metaphase I, anaphase I, telophase I, and meiosis II, to understand haploid gamete production through crossing over and independent assortment.

Explore how mitosis and meiosis share the cell division process, similar phases and chromosome movement, then contrast their roles in somatic versus germ cells, divisions, genetic variation, and chromosome number.

Explore how cellular transport sustains homeostasis by enabling nutrient uptake, waste removal, and signaling, through diffusion, osmosis, facilitated diffusion, active transport, endocytosis, and exocytosis.

Compare active transport and passive transport across cell membranes, noting ATP-driven movement against the gradient (such as the sodium–potassium pump) versus diffusion, osmosis, and facilitated diffusion that maintain homeostasis.