What a cell is, the cell theory and who built it, an overview of cells and their sizes and shapes, and the prokaryotic cell with its envelope, mesosomes, ribosomes and inclusion bodies.
3 lessons, about 1 h 15 min3 simulations10 problems3 practice questionsPython in every lesson
Created by StemPy LabEvery living thing is made of cells. Hooke named cells in cork, and Leeuwenhoek first saw living ones. Brown found the nucleus. Schleiden and Schwann showed that plants and animals are built of cells. Virchow added that every cell comes from a cell that already exists. Together these ideas form the cell theory.
Cells with a membrane-bound nucleus are eukaryotic; cells without one are prokaryotic. A cell has a plasma membrane, cytoplasm and organelles, some bound by membranes and some not. Cells range from Mycoplasma, about 0.3 µm long, to the egg of an ostrich. Their shapes suit their work, and their small size keeps the surface large for the volume.
Prokaryotes include bacteria, blue-green algae, mycoplasma and PPLO. Most have a cell envelope of glycocalyx, cell wall and plasma membrane. They have no nuclear membrane: the DNA lies naked in the nucleoid, with plasmids beside it. Mesosomes, chromatophores, 70S ribosomes, inclusion bodies, flagella, pili and fimbriae complete the cell.
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