Cell Discovery Unknown before the invention of the microscope Cells too small to see with eyes Robert Hooke 1665 Simple microscope to look at cork Looked like “cells” or small rooms Anton van Leeuwenhoek 1685 Designed his own microscope and looked at single celled organisms

Cell Theory A summary of experimental findings about cells All living things are composed of one or more cells Cells are the basic unit of structure and organization of all living organisms Cells arise only from previously existing cells, with cells passing on copies of their genetic material

Prokaryotic Cells No organelles No nucleus Single celled Bacteria Cellular functions take place anywhere in cell No nucleus Genetic material (DNA) is free floating in cell DNA is circular Single celled Bacteria

Eukaryotic Cells Have organelles Have nucleus Membrane bound structures Allows cellular functions to take place in specific places Have nucleus Contains genetic information DNA is linear Multicellular animals or plants Some unicellular Yeast and algae

Both Prokaryotic and Eukaryotic Have cell membranes

Prokaryotic and Eukaryotic 1. 2. 3. 4.  

Plasma Membrane Separate the cell from the environment Selective Permeability Allows some molecules to pass through Keeps some molecules in Keeps some molecules out

Structure of the Plasma Membrane Phospholipid bilayer Two layers of phospholipids Water-loving “heads” Water-hating “tails” Water soluble substances do not move through Transport proteins Move some things in or out of the cell Like tunnels through the membrane

What else is stuck in the plasma membrane? Cholesterol Maintains fluidity Carbohydrates Help identify cells

Cell Organelles – All Eukaryotes Nucleus – Control Center Ribosomes - Makes proteins Endoplasmic Reticulum- Makes proteins Golgi Apparatus – Packages proteins Vacuole – Stores cell materials Mitochondria- Supplies energy to cell Cell membrane - Flexible boundary

Eukaryotic Cell Structures Found…. Only in Animal Cells Lysosome Digestive enzymes Centriole Plays a role in cell division Only in Plant Cells Cell Wall Inflexible barrier Chloroplast Where photosynthesis takes place

Cell Organelles Cell Membrane Phospholipid bilayer Barrier Selective permeability Cytoplasm “Insides” of the cell Semi fluid

Cell Organelles Cytoskeleton Supports organelles Protein Helps transport cell products Nucleus Contains DNA Double membrane

Endoplasmic Reticulum Cell Organelles Ribosomes Produce protein Made of RNA and protein Float free or attached to Endoplasmic Reticulum Endoplasmic Reticulum Synthesizes macromolecules Rough – has ribosomes attached Smooth – no ribosomes

Cell Organelles Golgi Apparatus Modifies proteins Packages proteins for transport out of cell Mitochondria Produces energy for the cell Breaks down polysaccharides

Cell Organelles Lysosome Digests foreign invaders Recycles cell products Vacuole Storage of cell products Storage of waste products Plants have a large vacuole

Cell Organelles Chloroplast Plants only Site of photosynthesis Gives plants green color Cell Wall Plants only Gives plants structure Made of cellulose