Learning Goals 1. Describe the 3 parts of the Cell Theory and discuss the history behind it. 2. Compare and Contrast a Prokaryotic & Eukaryotic Cell 3. Describe the characteristics of a virus. Is a virus a cell? Is a virus alive?
History of Cells
The Discovery of the Cell Before microscopes people believed diseases were caused by curses and supernatural spirits People had no idea that bacteria existed Microscopes enabled scientist to view and study cells Cell - the smallest units/building blocks of all living organisms
Early Microscopes Robert Hooke –1665 he used a compound light microscope to study cork –He gave these boxed- shaped structures the name “CELL” b/c it reminded him of the small rooms monks lived in ?
Spontaneous Generation Vs. BioGenesis Spontaneous Generation= Living things coming from non-living things –Ex. Put a broom in the corner and eventually it will produce mice –Ex. Hay in a barn will produce mice
Spontaneous Generation Vs. BioGenesis 1668 – Francesco Redi – Disproved Spontaneous Generation –Meat in jars
Spontaneous Generation Vs. Biogenesis Matthias Schleiden concluded that all plants are composed of cells Theodore Schwann reported that animals are also made of cells Rudolf Virchow Developed concept of Biogenesis –Biogenesis = living cells come form other preexisting cells
Why Cells are Important What happens inside cells causes us to be who we are. (Genes) All diseases start at the level of the cell. All growth and life starts from a single cell.
Cell Theory 1. All living things are made of cells 2. Cells are basic units of life 3. All cells are made from other cells
Types of cells 1. Prokaryote2. Eukaryote
Prokaryotic Cells (Prokaryotes) Simplest, “primitive” cells with: –NO membrane-bound organelles (“little organs”) –NO nucleus: genetic material floats free in cell pro = before karyo = nucleus
Ex: Kingdom Bacteria
Eukaryotic Cells (Eukaryotes) Unicellular or multicellular Cells contain: – a nucleus (with DNA) – membrane-bound organelles Eu = truekaryo = nucleus Complex internal structure –“Compartments” allow many different chemical reactions to take place simultaneously
Examples: –Kingdom Protista – protozoa, algae, amoeba Kingdom Fungi – mushrooms, molds, yeast
Kingdom Plantae (Plants)– ranges from moss to flowering plants Kingdom Animalia (Animals) – ranges from tiny worms to humans
What about Viruses? -Are they alive? What do you think? CONS –Cannot grow or replicate without host (dormant) –Are not cells PROS –Have genetic material (DNA or RNA) –Can replicate (with host) –Have a protein coat
Viruses In general, not considered living Made of DNA (or RNA) surrounded by a protein coat Are NOT cells & cannot grow
Viruses are extremely small!