The cell theory

Cell theory – First part Cell are the basic structural and functional unit of living organisms

Levels of organization Cell -> Tissue -> Organ -> Organ System -> Organism

Levels of organization Cell – the basic structural and functional unit of tissue Tissue – a collection of cells of the same type that comes together to perform a function Organ – a collection of tissues which come together to perform a function Organ system – a collection of organs that come together to perform a function Organism – a collection of organ systems

Cell theory – second part All living things are made up of cells containing DNA and RNA and surrounded by a membrane

Cell theory – third part Cells arise from other cells

Two types of cells Prokaryotic cells – Always unicellular NO nucleus Free floating circular DNA NO organelles except ribosomes EX : Bacteria cells Eukaryotic cells – two types : Plant and Animal Unicellular or multicellular DNA enclosed in a nucleus Membrane bound organelles EX : plants, animals, protists, and fungi

Two types of cells

Endosymbiotic theory Bacteria began living inside other bacteria and over time a dependence formed which created complex eukaryotic cells

Evidence for the endosymbiotic theory We see symbiosis between bacteria in modern species. Mitochondria and Chloroplasts have their own DNA Mitochondria and Chloroplasts have similar methods of reproduction as prokaryotic cells Mitochondria and chloroplasts have double membranes

Cell Theory recap Cells are the basic structural and functional unit of living organisms All living things are made up of cells containing DNA and RNA and surrounded by a membrane Cells arise from other cells