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Viruses Viruses I. 1. They are Nonliving i. Viruses are NOT cells… they carry on no life function on their own they can be stored for years and still be viable ii. Viruses do NOT replicate themselves this happens only after invading a living Host Cell iii. Unprecedented diversity A virus for every species RNA viruses lack any error proofreading when being copied – leads to different forms of the same viruses that the body does not recognize 2. Named after the disease they cause or the tissue they infect i. Rabies virus & Polio virus ii. Adenovirus (the Common Cold): infects the adenoid tissue in throat and nasal cavity 3. Viruses are small i. Smaller than the smallest known cell ii. about 100 times smaller than bacteria. Rabies virus 1 nanometer (nm) = one billionth of a meter eukaryotics cells 10,000-100,000 nm prokaryotics cells 200-10,000 nm viruses 50-200 nm viroids 5-150 nm 4. Viruses are classified by a number of different characteristics: a. b. c. d. e. f. Shape Nucleic Acid content – DNA or RNA Presence or absence of an “envelope” Type of host it affects How it is transmitted Vectorsi. any organism or object that carries or transmits disease causing organisms ii. Ex. needles, worms, water, mosquitoes, etc. g. Attachment process i. they can only attach to specific cells or cell types. Types of Viruses II. 1. DNA viruses i. They will not change much overtime ii. DNA tends to stay stable i. 2. Ex.: Adenovirus (common cold) / Poxviruses (small pox) RNA viruses i. They will change often b/c they do not proofread errors when the RNA gets copied. i. Ex. HIV (causes AIDS)/ Influenza (Swine flu) III. Virus Structure 1. Made of mainly Protein 1. Proteins on surface help viruses attach to cells 2. Has a Coat called Capsid a. Contains the Nucleic acid Core b. either DNA or RNA RNA Viruses= HIV destroys white blood cells ii. DNA Viruses= Cold sores and Smallpox capsid D N A tail sheath i. 3. Some viruses have an Envelope a. an additional coating b. enhances the viruses’ ability to enter an organism or host cell tail fiber V. Outbreaks i. ii. Virology—the study of viruses (and virus-like agents) Epidemic—when cases of a given disease substantially exceed “expected” cases of that particular disease iii. Pandemic—occurs when an epidemic spirals out of control, spreading across large regions (i.e. a continent or worldwide) VI. Treatments i. ii. Antibiotics DO NOT treat viral infections, only bacteria Vaccines— are deactivated viruses that trick the immune system into thinking there has already been an infection. i. Vaccines stimulate antibody production ii. Antibodies mark which items in the body get destroyed iii. Antibodies will “remember” a virus iv. Now when the body is exposed to the harmful virus again the antibodies will be made faster to kill the virus. I. Bacteria A. Belong to Two Kingdoms 1. Archaebacteria i. live in extreme environments ii. 02 free environment iii. Extremophiles 2. Eubacteria i. The most common ii. Live in non-extreme environment iii. Some are parasites B. You can find bacteria in fossils C. Characteristics: 1. 2. 3. Unicellular May live in colonies Prokaryotes 1. 2. 4. They have no nucleus Their DNA is floating freely in the cell Autotrophs (Producers) i. Photosynthetic ii. Chemosynthetic 5. Heterotrophic (consumers) 1. Feed off of organic material outside of themselves plasma membrane chromosome cell wall plasmid pili flagellum Lactobacilli: rod-shaped D. Bacterial Structure 1. 3 basic shapes i. rod (bacillus) ii. round (coccus/ cocci) iii. Spiral (spirilium) 2. 2 types of cell extensions Enterococci: round i. pili (pilus) –hair-like structures that helps them stick to surfaces and each other ii. flagella –allows some bacteria to move 3. Plasmid i. small circle of DNA (a single chromosome) 4. Capsule i. is an external protective layer that keeps it from being destroyed 5. Cell walls – Similar to plants i. Penicillin (antibiotic) stops the formation of cell walls (Helps destroy bacteria) Spirochaeta : spiral E. Adaptations 1. Bacteria live in various habitats and have several adaptations i. They can breakdown dead matter. i. Prevents buildup of deceased material ii. Some can use poisonous substances as food (ex. Oil) Bioremediation iii. They can exist in extreme hot/cold 2. High rate of Mutualism i. The relationship between two species with both getting benefits 3. 4. The bacteria in your intestines help to breakdown food faster. Some need an O2 environment = aerobic (Ex. Tuberculosis – affects lungs) Some can’t live in O2 environment = anaerobic (Botulism -food poisoning) II. Bacteria Life Cycle A. Asexual Reproduction 1. Binary Fission i. Reproduce (Mitosis) by dividing into two cells ii. Can happen very quickly B. Sexual Reproduction 1. Conjugation i. One bacteria transfers all or part of its chromosome (DNA) to another cell through pilli that connects the two cells ii. Results in bacteria with new genetic composition Defense III. A. How do Antibiotics work? 1. They stop the creation (synthesis) of bacterial cell walls or cause the cell walls to break apart. 2. Antibiotics interfere with the functions (metabolic processes) of bacterial ribosomes (i.e. protein synthesis). 3. Unlike bacteria, viruses don’t have cell walls or ribosomes, so antibiotics have no effect on them. B. Bacteria are gaining resistance to antibiotics through: i. overuse underuse misuse A bacterium may already have an gene (DNA) for antibiotic resistance on the plasmid ii. A copy of the plasmid is transferred through conjugation. iii. Resistance quickly spreads through many bacteria. Good Bacteria and Bad Bacteria IV. A. There are good and bad bacteria 1. Good bacteria are used to help fight disease/ create food (cheese)/ and deal with pollution i. EX. Lactobacillus acidophilus, Dehalococcoides ethenogenes 2. intestinal bacteria make up approximately 95% of the total number of cells in the intestinal tract. 3. Bad bacteria cause life threatening diseases i. Done by invading tissues or creating toxins ii. EX. E-coli and streptococci