SECTION 3.1 WHERE LIFE HAPPENS1. Living things can be unicellular (one cell) or multicellular. A bacterium is a type of unicellular organism.2. About 8,000 of the smallest bacteria could fit into one of your red blood cells.3. The longest cells are the thin nerve cells found in large animals and can be over a meter long.4. The cell with the largest volume is an unfertilized ostrich egg5. The shape of a cell is linked to its function. For example, a long nerve cell is long and carries messages from your spine to your toes. Contraction and relaxation of muscle tissue are responsible for movement in animals. A SMALL NEW WORLD1. In the 1600s, people only knew about organisms they could see with the naked eye.2. A trio of Dutch eyeglass makers invented the microscope in the late 1500s. It consisted of a tube with lenses ground from rock crystal and magnified objects up to 9 times their actual size.3. In 1665, the British scientist Robert Hooke published a series of drawings illustrating what he had observed under a microscope.4. In the early 1670s, Dutch fabric store owner Anton van Leeuwenhook began grinding lentils as a hobby. He used hand-held microscopes to examine materials such as pond water and blood. BIOLOGISTS BUILD A THEORY1. In the 1830s, many biologists used the microscope as their primary investigative tool2. Mathias Schleiden was a botanist, a scientist who studies plants. He discovered that the plant parts he examined were made of cells. In 1838, Schleiden generalized that all plants are made up of cells.3. Theodor Schwann studied and researched animals. His microscopic research on animal parts led him to generalize that all animals were made of cells.4. In 1858, a German doctor named Rudolf Virchow challenged the idea of ​​spontaneous generation. Virchow reasoned that new plant cells come only from existing plant cells and new animal plant cells come only from existing animal cells. Cell theory consists of three principles: Cells are the basic units of all life. All organisms are made up of one or more cells. All cells arise from existing cells.VIEW SMALLER1. One of the most important tools used by biologists is the microscope.2. Until the 1950s, microscopes were optical microscopes, that is, instruments that used either sunlight or artificial light to view objects. With the advantage of being able to enlarge many microscopic objects while they are alive.