> [!quote] What Even Are Cells? > Cells are the smallest unit of life, yet they lack a true consciousness and are not capable of "thinking" the way that multicellular organisms can. # Cells > [!abstract] Basic Features of All Cells > 1. Contain a Biological Membrane > - An important feature of cells that allows for the controlled flow of molecules in and out of the cell. > 2. Contain Cytosol > - > 3. a > - > 4. a > - - [[Biological Criteria for Life]] There are four major classes of [[Biological Macromolecules]] that are crucial to all life (both eukaryotic and prokaryotic) > [!info] Early Development of Life > - [[History of Microbiology]] > - [[Origin of Life]] ## The Cell Theory The Cell is the basic unit of life: - Similar to how atoms are the basic unit of chemistry, cells are one of the smallest building blocks of life that allow larger and more complex organisms to function All living organisms are composed of one or more cells (unicellular vs multicellular) Cells arise from preexisting cells > [!info] The Modern Cell Theory > Energy flow occurs within cells > Hereditary information ([[Nucleic Acids|DNA]]) is passed on from cell to cell > All cells have the same basic chemical composition These theories lead to more complex definitions of life and the [[Biological Criteria for Life|criteria]] that is required for it (which is still under much debate). ## Basic Components of All Cells 1. **Contain a Plasma Membrane** - An important feature of cells which allows for the controlled flow of molecules in and out of the cell. 2. **Contain Cytosol** - A semi-fluid substance that fills the inside of cells 3. **Contain Chromosomes** - Contains the DNA of the cell 4. **Contain Ribosomes** - A crucial organelle which creates proteins [[Cytoskeletons]] ### Eukaryotic Cells Plant Cells: Chloroplasts, Rigid Cell Wall, Plastids Animal Cells: Lysosomes, Cilia, Centrioles - [[The Endomembrane System]] ### Prokaryotic Cells - No Nucleus - DNA is stored in an unbound region called the nucleoid - No membrane-bound organelles - [[Pasted image 20220803053705.png|Can thrive in almost any environment]] [[Bacteria Cell Envelope]] ## Cell Processes - [[Basic Cell Processes]]