Transcript Viruses
Viruses -Segments of RNA or DNA contained In a protein coat Viruses are not living!!! 1) Viruses are not made of cells 2) Viruses do not grow 3) Viruses can’t reproduce on their own 2 Main Shapes of Viruses 1) Helical Virus - Rodlike - Capsid proteins winding around core in a spiral 2 Main Shapes of Viruses 2) Polyhedral Virus -Many sides, roughly spherical -Most efficient at holding viral genes Bacteriophages Viruses that infect bacteria Structure is polyhedron capsid w/ helical tail How can a Virus Reproduce? Infect a living cell Living cell reads viral nucleic acids and produces more viruses Bacteriophages go through the lytic or lysogenic cycle Lytic Cycle Viral genes are injected into the host cell Host cell replicates viral genes and make viral proteins (capsids) Genes and viruses are put together Process repeats until cell bursts Lytic Cycle http://student.ccbcmd.edu/courses/bio141/lecgui de/unit3/viruses/lytlc.html#rellyt Lysogenic Cycle Viral gene is inserted into host chromosome (provirus) When cell divides, provirus divides Change in environment can begin lytic cycle Lysogenic Cycle http://student.ccbcmd.edu/courses/bio141/lecgui de/unit3/viruses/repmatly.html http://www.youtube.com/watch?v=_J9-xKitsd0 Emerging Viruses Viruses that evolve in geographically isolated areas and are pathogenic to humans Hanta Virus Ebola Virus Hantavirus Pulmonary Syndrome May 1993 Acute respiratory symptoms Breathing in air contaminated w/ the virus Urine and feces Ebola Virus 1976 Severe, often fatal disease Found in humans and non-human primates Gabon, Sudan, the Ivory Coast, Uganda, and the Republic of the Congo. http://www.cdc.gov/ncido d/dvrd/spb/mnpages/disp ages/ebola/ebolatable.ht m Why do we encounter emerging viruses? http://ffh.films.com/id/9505/The_Emerging_Virus es.html Prions Proteins and no nucleic acids Cause disease by influencing how proteins fold Misfolding spreads like a chain reaction Mad Cow Disease Creutzfeldt-Jakob disease Bacteria http://video.google.com/videosearch?hl=e n&q=bacteria&safe=vss&um=1&ie=UTF8&sa=N&tab=wv# What are Bacteria? Single celled, prokaryotic organisms 1/10 the size of most eukaryotic cells -http://www.cellsalive.com/howbig.htm Have a single circular piece of DNA Reproduce by Binary Fission Anaerobic and aerobic processes (Euk are mostly aerobic) Flagella is simple Some have pili Pili http://microbiologybytes.com/video/photosynthesis.html Along with gel-like capsule, pili help bacteria adhere to surfaces Enable Conjugation-two organisms exchange genetic material Cell Walls Most Bacteria have 2 types of cell walls -Gram-negative -Gram-positive The 2 types differ in susceptability to antibiotics -Chemicals that interfere with life processes in bacteria Three Basic Shapes Bacillus (buh SIHL uhs) -Rod shaped Coccus (KAHK us) -Round shaped Spirillium (spy RIHL uhm) -Spiral shaped Baccilus Northwestern Link Coccus http://biology.northwestcollege.edu/biology/b1010lab/bacillus1.jpg Spirillium http://biology.northwestcollege.edu/biology/b1010lab/bacillus1.jpg Which is Which??? Aggregating Bacteria Strepto- form filaments Staphylo- form clusters How Bacteria Cause Harm Metabolize their host Secrete chemical compounds Metabolizing their host Acne Propionibacterium acnes, grow in the oil glands of skin Metabolize certain kind of oil produced by glands Oil glands increase oil production during puberty Food increases so bacteria population increases http://www.nlm.nih.gov/medlineplus/tutorials/acne/htm/_no_50_no_0. htm Myths Metabolize their Host Mycobacterium tuberculosis Once one of most common causes of death (1.6 million in 2005) Incidence rates have stabalized Contracted from inhaling droplets of moisture containing bacterium Cough up sputum (saliva mixed w/ mucus or puss) and blood, chest pain, fever, fatigue, weight loss Over one third of world population is infected (5-10% will become sick) Secrete Chemical Toxins Staphylococcus aureus Causes most common food poisoning Nausea, vomiting, diarrhea Secrete Chemical Toxins Clostridium botulinum Causes botulism From improperly heated canned food Double vision and paralysis May die because can’t breath 1g would is potent enough to kill 1 million people Relevance of Bacteria Living with you Food Antibiotics Living with You Streptococcus pneumoniae - present in upper respiratory tract of half the population E. coli - Present in small intestine. Aids in digestion Streptococcus aureus - causes most common staph infections. Found in Nose and on skin Food Fermented food Pickles, buttermilk, cheese, saurkraut, olives, vinegar, and sourdough bread Antibiotics Can be naturally produced by fungus or imitated chemically Penicillium was first used antibiotic Either stop bacteria from multiplying (bacteriostatic) or interferes with formation of cell wall or cell contents (bactericidal) Over 100 types and most often perscribed medicine