All Living Things Are Made of Cells

Hey there! I'm Lumi, and I want to show you something wild — everything alive, from the mushroom on your pizza to the oak tree in your yard to YOU, is built from the same basic unit: the cell. Scientists figured this out piece by piece. In the 1600s, Robert Hooke looked at thin slices of cork under an early microscope and saw tiny box-like spaces. He called them "cells" because they reminded him of small rooms. Then Anton van Leeuwenhoek used a homemade microscope to discover living single-celled creatures in pond water — he called them "animalcules." By the 1830s, Matthias Schleiden (studying plants) and Theodor Schwann (studying animals) each concluded that ALL living things are made of cells. More than a decade later, by 1855, Rudolf Virchow added the final piece: every cell comes from a pre-existing cell. No cell appears out of thin air. That gives us the three statements of Cell Theory: 1. All living organisms are made of one or more cells. 2. The cell is the basic structural and functional unit of life. 3. All cells come from pre-existing cells. Cells can live alone — a single-celled organism like an amoeba or a bacterium is a complete living thing all by itself. That is called unicellular. Your body, on the other hand, is multicellular — made of roughly 37 trillion cells that work together as tissues, organs, and organ systems. Not all cells look the same. Bacteria are prokaryotes — their cells have NO nucleus; their DNA floats freely inside. Your cells, plant cells, and fungal cells are eukaryotes — they have a true nucleus that holds the DNA, plus other membrane-bound organelles. Here is the key hint: whenever a question asks whether something is alive, the answer always connects back to cells. No cells? Not alive. Comes from no prior cell? Impossible in nature. Cell theory is the foundation everything else in biology rests on.