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• In 1665, Robert Hooke discovered cells in slices of cork
• Anton van Leeuwenhoek was the first to observe living cells in a microorganism in 1673
• Matthias Schleiden stated in 1838 that all plants are composed of cells
• Theodor Schwann stated in 1839 that all animals are composed of cells, claiming all living things are composed of cells
• Rudolf Virchow, in 1858, proposed that all cells come from preexisting cells
• Cell Theory:

  1. All organisms are made up of cells.

  2. Cells are the basic unit of structure and function in all organisms.

  3. All cells come from cells that already exist
• The Plant Cell consists of a cell wall and protoplast, which includes cytoplasm and a nucleus
• The cytoplasm in a plant cell includes membrane-bound organelles like plastids and mitochondria, systems of membranes like endoplasmic reticulum and dictyosomes, and nonmembranous entities like ribosomes, actin filaments, and microtubules
• The plasma membrane in a plant cell mediates substance transport, coordinates cellulose microfibril synthesis, and relays signals for cell growth and differentiation
• The nucleus in a plant cell controls cell activities, stores genetic information, and is surrounded by a nuclear envelope with pores for macromolecule passage
• Chloroplasts in plant cells contain chlorophyll, conduct photosynthesis, have their own DNA and protein-synthesizing machinery, and divide by fusion
• Mitochondria in plant cells are sites of cellular respiration, contain their own DNA and protein-synthesizing machinery, and divide by fusion
• Vacuoles in plant cells are membrane-bound organelles filled with cell sap and have different functions within the cell
• The cytoskeleton in plant cells consists of microtubules, microfilaments, and intermediate filaments, involved in cell division and assembly/disassembly
• Lysosomes in plant cells digest organic compounds, peroxisomes assist in photosynthesis, and many plant cells accumulate lipids
• Cellulose cell walls in plant cells are composed of cellulose microfibers and a matrix of noncellulose molecules like hemicelluloses and pectins
• Plasmodesmata in plant cells allow the transport of substances between cells by connecting their living protoplasts