Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Oncolytic virus wikipedia , lookup
Virus quantification wikipedia , lookup
Social history of viruses wikipedia , lookup
Endogenous retrovirus wikipedia , lookup
Bacteriophage wikipedia , lookup
Plant virus wikipedia , lookup
Negative-sense single-stranded RNA virus wikipedia , lookup
Introduction to viruses wikipedia , lookup
Bacteria & Viruses Chapters 24 & 25 Topics: Evolution/Classification Morphology Humans & Bacteria/Viruses 1 Bacteria Bacteria: Unicellular prokaryotes Evidence has been found in fossil record as long ago as 3.5 B years Bacteria found everywhere on Earth including the harshest environments Classified into 2 kingdoms: Eubacteria Archaebacteria 2 Archaebacteria Cell membranes and DNA differ from eubacteria species Peptidoglycan is absent from their cell membranes Common in all environments, but is found in harsh environments as well Methanogens – converts H2 & CO2 to CH3, anaerobic Extreme halophiles – live in salt environments, salt used to make ATP Thermoacidophiles – live in acidic environments with high temps (ocean vents) 3 Eubacteria All other bacteria fall into this group Occur in 3 shapes: Bacilli – Rod shaped Cocci – Sphere shaped Spirilla – Spiral shaped Cocci occurring in strings are streptococci Cocci occurring in clusters are staphlococci 4 Bacterial Shapes 5 Eubacteria, con’t The cell membrane of many eubacteria is unique and stains in a certain way Gram Positive (have a thick layer of peptidoglycan) – appear purple after stain Grame Negative (thin layer of the peptidoglycan) – appear pinkish after stain Eubacteria have differences in antibiotic susceptabilities & reactions to disinfectants, produce different types of toxins 6 Morphology Have a cell wall (a few don’t) containing peptidoglycan and other lipids, carbohydrates Many gram negative bacteria are antibiotic resistant (oh, no!) Cell membrane & cytoplasm – cellular respiration occurs in cell membrane b/c it contains NO mitochondria DNA is a single loop in cell 7 Morphology, con’t Capsules – outer covering (most bacteria produce this) which protects it against desiccation, harsh temperatures & chemicals Pili – short, hairlike structures on surface, used in some species to transfer DNA from one organism to another Movement – many move by using flagella, cilia, body movements Endospores – dormant structure procuced by a gram-positive bacteria to enable it to withstand harsh conditions Bacillus and Clostridium genuses produce these 8 Streptococcus pyogenes Strep Throat 9 Escherichia coli 10 Staphylococcus epidermidis 11 Borrelia berdorferi Spirochete Deer Tick Rocky Mountain Spotted Fever 12 Disease (Page 478 for list) Toxins – some diseases caused due to the toxins the bacteria produce Exotoxins – proteins from gram-positive bacteria, secreted into environment Tetanus Endotoxins – lipid + carbohydrate associated w/ outer membrane of gram-negative bacteria, only released when organism dies Streptococci Antibiotics – kill bacteria by interfering with its functioning Penicillin, tetracycline, sulfa drugs, Pg 479 13 Prions NOT ALIVE & very small (only about 250 amino acids long w/ no nucleic acid) Abnormal proteins that cause disease Cause diseases such as scrapie, BSE, CJD (Creutzfeld-Jakob) Affect central nervous system Kills neurons Onset is very slow 14 Normal Protein Prion or Deformed Protein 15 Viruses Composed of a protein coat covering a nucleic acid (either DNA or RNA) NOT ALIVE Works by invading a living host cell and taking over the cell’s machinery turning it into a virus manufacturing “plant” Come in a variety of shapes and sizes 16 Virus Types Viruses contain either DNA (single or double stranded) or RNA DNA viruses enter a host cell, begin directing the cell to make more viruses RNA viruses (retroviruses) enter host cell, and using reverse transcriptase, use their RNA to make a template for DNA and the new DNA directs cell to make more viruses Page 489 chart on viruses affecting humans 17 Bacteriophage Virus that attacks a bacterium Structure: Capsid (head + tail), Tail fibers, nucleic acid is in the head and is injected into the bacterium when it grabs hold 18 Viral Cycles Lytic Cycle (viruses that undergo this are virulent – cause disease) The virus invades host cell, produces new viruses, destroys host cell as new viruses are released Lysogenic Cycle (viruses that undergo this are called temperate viruses, do not kill host cell right away) Host cell becomes a prophage and each time it replicates, so does the viral DNA in it 19 Disease Many significant diseases are viral in nature – for example Common cold Smallpox Mumps Measles Polio Rabies Chickenpox Hepatitus Cancer Papilloma virus Vaccines used to fight viruses Boost immune system antibodies Attenuated & Inactivated Antiviral drugs – stop replication of viruses Acyclovir (inhibits replication) AZT (azidothymidine) – inhibits reverse transcriptase of retroviruses (HIV is a retrovirus) Protease inhibitors (inhibits synthesis of capsid) 20