Transcript Chapter 34
Viruses • • • • DNA or RNA or both? Surrounded by protein Not cellular Not “alive” What characteristics of “living” organisms do viruses lack? NO cell organization response to stimuli homeostasis growth development Maybe? regulation reproduction Yes Heredity Viral Classification • Replication dependent on living organisms • Often highly specific to a host • Highly specific cells within a host Shapes Replication in Bacteriophage Lytic Cycle Lysogenic Cycle 1. 2. Attachment Penetration 3. 4. 5. Synthesis Assembly Release • Historically lethal • High mutation rate (less problematic) • Infects many types of animals (highly problematic) Virus Strains • Classified according to type of proteins • Recombination between different strains causes problems • Hong Kong Flu − H3N8 – ducks − H2N2 – humans Ebola • • • • • • • 5 different viruses Discovered in mid 1970’s Single stranded RNA Causes hemorrhagic fever 2014 outbreak - 8000 deaths High mortality rate Transmission – broken skin/mucous membranes • Each day 6000 people die in Africa from Aids 11,000 newly infected • “All of a sudden, the beaver flips over and comes back to life” http://www.washingtonpost.com/local/cr ime/woman-83-attacked-by-rabidbeaver-at-lake-barcroft-in-fairfaxcounty/2012/09/05/e778ec02-f79411e1-8253-3f495ae70650_story.html Prokaryotes Bacteria There are more individual prokaryotes in your large intestine than there are cells in your body Life in the clouds Santl-Temki et al. 2013. PLOS one Prokaryotes • • • • • • • • • • • Small Unicellular No nucleus Asexual reproduction Modes of gene transfer Lack organelles Little morphologial diversity Simple flagella Metabolic diversity Ecological diversity Oldest life-form Gram-negative bacteria Outer membrane Pili (structures used for attachment) Peptidoglycan layer Cell wall Nuclear area (nucleoid) Storage granule Plasmid (DNA) Flagellum Ribosomes Bacterial chromosome (DNA) Capsule Plasma membrane Prokaryote Diversity https://www. youtube.co m/watch?v= v1NnMmw8 v80 Gene Transfer Between Prokaryotes Figure 6.2 6-1 Table of metabolic Diversity in Prokaryotes Prokaryotic Diversity • Recognition that there are two fundamentally different kinds of prokaryotes – Bacteria – Archaea • 1977: Carl Woese – RNA analysis These "bacteria" appear to be no more related to typical bacteria than they are to eukaryotic cytoplasms. 1987 – 12 phyla 2003 – 29 phyla 2012 – 52 phyla? Bacteria vs. Archaea • Cell walls contain peptidoglycans • Plasma membrane composed of lipid bilayer • Antibiotics inhibit growth • No true peptidoglycan in cell walls • Bi-layer with different lipids and bonds – monolayer • Growth not inhibited by antibiotics Several other differences associated with DNA replication and gene expression • Simple RNA polymerase enzyme • Unique translation initiation • Multiple RNA polymerases (Like Eukaryotes) • Translation is similar to Eukaryotes Archaea Diversity Many technological applications using prokaryotes Using bacteria to produce pharmaceuticals