Transcript Prokaryotes
Prokaryotes •Objectives: •Know the Differences between Viruses and Bacteria •How do viruses and bacteria cause disease? What is a prokaryote? • Prokaryotes are defined as “ unicellular organisms that lack a nucleus.” • Unicellular means: that these are single celled organisms. • “lack a nucleus” means that prokaryotes have genetic material (DNA) but it is not separated from the rest of the cell by a membrane. Two Types of Prokaryotes • Bacteria: 1) Larger Domain (more species) 2) Live almost everywhere 3) Have a cell wall made of peptidoglycan <-- E. Coli Bacteria Peptidoglycan • Found in the cell walls of bacteria, peptidoglycan is a polymer of amino acids that surrounds the cell membrane Two Types of Prokaryotes • Archaea • No peptidoglycan in the cell walls • Cell membranes have different lipids • DNA is more like ours than bacteria • Extremophiles Extremophiles Structure of a Prokaryote Prokaryote DNA Shapes of Bacteria • Spirilla: corkscrew shaped bacteria • Cocci: spherical • Bacilli: Rodshaped Structure: Virus vs. Prokaryote • Viruses can come in different shapes, but do not have a means of locomotion and tend to be smaller and less complex. Prokaryote Structure • Come in different shapes, but are generally larger and more complex. • Some have means of locomotion (movement) • Have a cell wall and cell membrane How would you design an antibiotic to target bacteria? • You could target the peptidoglycan in the bacteria cell wall. When the wall is broken the bacteria will lyse (burst). What bacteria need to survive? • Prokaryotes need “chemical energy” in order to survive. • Different types of bacteria use different sources of energy. • Photoautotrophs use sunlight to photosynthesize. Metabolisms • Photoautotrophs need sunlight so they can make their own chemical energy. • Heterotrophs consume other organisms or organic molecules for food Do viruses have a metabolism? Virus vs. Prokaryote: Metabolism • Viruses invade cells when they encounter them, but do not have a metabolism • Prokaryotes require chemical energy, of one type or another, to survive. <-- Flesh eating bacteria Prokaryote Reproduction • Binary Fission: (asexual reproduction) • A bacterium grows to twice its size and divides into two daughters • Conjugation: bacteria share DNA Virus Reproduction • Lytic Infection: • Get into cell and reproduce until it bursts. • Lysogenic Infection: • Enter a cell and bind its DNA to the cell’s. When the cell reproduces so does the virus. • Then the virus will enter the lytic cycle Prokaryotes Alive? • They respond to their environment, reproduce, have a metabolism, and grow. • Definitely a living organism. 5 Second Rule?