Chapter 20 Viruses and Bacteria

Viruses-

What is a virus? Segments of nucleic acid surrounded by a protein coat. Pathogens – cause disease Smaller than most cells

Viruses are Non-Living! What are the P PP Properties of Life? Made of cells, able to grow, reproduce, store DNA Viruses are: not made of cells cannot grow can only reproduce by infecting other cells Therefore VIRUSES ARE NOT LIVING

Viral Structure Protein coat = capsid DNA or RNA (inside capsid) Envelope = surrounds capsid (membrane) Glycoprotein- attaches (parts from host cell)

Lytic Cycle Virulent viruses – cause disease 1. Attach at receptor site 2. Injection of DNA 3. Host cell is taken over and forced to make new viruses 4. Host cell breaks open (lysis)

Lysogenic Cycle Temperate virus – doesn’t kill host cell immediately. 1. Virus attaches 2. Injects DNA 3. Viral DNA mixes with host DNA 4. Goes through divisions 5. Host cell undamaged

Viruses HIV Papovavirus Adenoviruses Herpesviruses Poxviruses Picornaviruses Myxoviruses Rhabdoviruses Retroviruses BSE CJD Chickenpox common cold measles mumps polio rabies Hepatitis Leukemia Liver cancer Burkitt’s Lymphoma Cervical cancer

Tobacco Mosaic Virus End of 19 th Century Tobacco mosaic disease 1935 Wendell Stanley extracted cause of disease (RNA and protein) Classified as viruses

HIV H uman I mmunodeficiency V VV V irus Causes AIDS (acquired immune deficiency syndrome) First: virus attaches to cell at receptors Second: trigger endocytosis (HIV fuses into cell)

Retroviruses: HIV

Papoviruses HPV

Adenoviruses Viral Conjunctivitis: with respiratory problems Keratoconjunctivitis

Herpesviruses Chickenpox / herpes simplex

Poxviruses

Myxoviruses Influenza A, B and C

Rabies Rhabdoriruses

measles, mumps

Common Cold- Rhinovirus

Polio

Bacteria

The Bacteria Domain Vs Eukarya Domain 7 Ways bacteria differ from eukaryotes No internal membranes Much smaller Single celled Circular DNA Binary Fission reproduction Flagella

Bacteria are classified and identified using characteristics: Cell Shape- cocci - round bacilli – rod spirillum - spiral Cell Wall Structure- 2 types Motility- flagellum, pili, slimy threads The bacteria domain

Gram Staining- process used to distinguish b/w each type of cell wall 2 types of bacteria cell walls 1. Composed mostly of peptidoglycan (Gram +) 2. Less peptidoglycan but additional outer membrane (Gram -) Cell Wall structure

Obtain Energy Photosynthesizers- 4 types (anaerobic) Cyanobacteria  created atmosphere Chemoautotrophs- live in soil (nitrogen fixing) and remove inorganic matter Heterotrophs- decomposers (aerobic)

Good & Bad Bacteria Good  streptomyces (antiboitics) Rhizobium (nitrogen fix on plants) Make cheese & clean industry Bad  Pathogens! Disease causing

PProkaryotes that cause disease MMycobacterium tuberculosis (TB) SStreptococcus pyogenes (Strep throat) mmethicillin resistant Staphylococcus aureus (MRSA), Diversity of Prokaryotic Life

Biological Warfare Anthrax Tetanus- Scythian Archers Ebola-Peloponnesian War Smallpox- Native Americans The Plague- early 14 th century in Asia

Antibiotic Resistance Prevent virus with vaccine Treat bacterial infection with antibiotic Misuse- not finishing prescription Multiple-Resistance- treatment with more than 1 anti-biotic & Anti-bacterial soaps

Importance of Bacteria Food & Chemical Production Pickles, cheese, olives, vinegar, sourdough breads, yogurts etc Chemicals like acetone (nail polish remover) Environmental Uses Harvest copper or uranium Eat away at carbon based spills (oils)