2 Introduction to Cells Cells are the basic units of organisms Cells can only be observed under microscopeBasic types of cells:Bacterial CellAnimal CellPlant Cell
3 The Cell Theory All living things are composed of cells. Cells are the basic units of structure and function in living things.New cells are produced from pre-existing cells.
4 Number of Cells Organisms may be: Unicellular – composed of one cell Multicellular- composed of many cells that may organize
5 Cells May be Prokaryotic or Eukaryotic Prokaryotes include bacteria & lack a nucleus or membrane-bound structures called organellesEukaryotes include most other cells & have a nucleus and membrane-bound organelles (plants, fungi, & animals)
6 Prokaryotes Nucleoid region contains the DNA Cell membrane & cell wall Contain ribosomes (no membrane) to make proteins in their cytoplasm
40 SystemSeveral organs and tissues work together to carry out a particular set of functions in a co-ordinated wayHuman : digestive, respiratory, excretory, circulatory and reproductive systemsPlant : root and shoot systems
41 Human Body Systems Examples of systems : Digestive System Respiratory SystemCirculatory SystemNervous SystemReproductive System