Viruses and Bacteria

Viruses  2 main parts- protein coat called a CAPSID and nucleic acid (RNA or DNA)  Host specific and cell specific- the cold virus infects moist mucous covered cells in your throat, not your big toe.  Requires a host cell for replication  Virus attaches to cell and then injects its nucleic acid into cell  Bacteriophage- virus that infects bacteria

2 Cycles  Lytic- kills the host cell  Lysogenic- viral nucleic acid is incorporated into host DNA and gets copied every time cell does mitosis. The viral DNA imbedded in host genome is called a prophage. The viral DNA imbedded in host genome is called a prophage.

Lytic Cycle 1. Virus attaches to host cell 2. Injects DNA or RNA 3. Host cell make virus parts 4. Capsid and Nucleic acid assembled into virus 5. Cell bursts and releases new viruses to go out and infect more cells Ex.- cold virus, measles Ex.- cold virus, measles

Lysogenic Cycle  Virus injects nucleic acid  Viral NA joins host DNA (now called a provirus)  As cell copies,so does viral NA  Can remain in the body  Under certain conditions like stress- virus goes into lytic cycle  Ex. Herpes and Chicken pox(Shingles)

Retrovirus-HIV  Different because it is an RNA virus  Makes DNA out of RNA (we learned that we make the RNA from the DNA for protein synthesis)  Uses reverse transcriptase (Enzyme)  Infects the white blood cells

 Viruses are known to cause cancer by disrupting growth and cell division (Cervical Cancer)  Prions- pieces of protein that change into a bad protein. In MAD COW- it causes the brain to become spongy.  Viroids- single stranded RNA that cause disease  1 st virus identified- Tobacco Mosaic Virus (TMV). Stunts plants growth  Vaccines available for some viral infections(measles,hepatitis)

Bacteria  Prokaryote- no membrane bound organelles  3 shapes- coccus coccus bacillus bacillus spirilla spirilla

 Flagella used for movement  Pili- used to exchange genetic material like resistance  Capsule- thick covering that increases pathogenicity (ability of bacteria to cause disease)  Eubacteria cell wall made of peptidoglycan  DNA -long circular piece found in nucleiod region

2 Kingdoms Archeabacteria  Cell wall doesn’t contain peptidoglycan  DNA sequencing closer to that of Eukaryotes. Live in unusual Live in unusual environments environments  No oxygen- anaerobic (methanogens)  High salt- halophilic  Hot acid springs Eubacteria  Common ones that cause disease- found everywhere  Can be: heterotrophic, photosynthetic, chemosynthetic (use S or N) heterotrophic, photosynthetic, chemosynthetic (use S or N)

Identification 1. Shape 2. Movement-with or without flagella 3. Cell Wall- Gram + have a thick peptidoglycan wall so they stain violet Gram + have a thick peptidoglycan wall so they stain violet Gram – have a thin peptidoglycan wall and thicker lipid wall so they stain pink. Gram – have a thin peptidoglycan wall and thicker lipid wall so they stain pink.

Metabolic Diversity  Chemoheterotroph- take in organic compounds  Photoheterotroph- photosynthetic, but also take in organic compounds  Photoautotroph- use light energy  Chemoautotroph- make organic compound from CO 2 but use S or N reactions to supply the energy.

Reproduction  Binary Fission- can reproduce every 20 minutes can reproduce every 20 minutes

Conjugation Conjugation  Bacteria can also transfer genetic material called a plasmid through their pili. Plasmids can contain DNA to make a bacteria antibiotic resistant.

Bacterial Environments  Bacteria can live in areas of different oxygen levels:  Obligate Aerobe- needs O 2  Obligate Anerobe- killed by O 2  Facultative Anaerobe- can live with or without O 2

Endospores  Bacteria can also produce ENDOSPORES- a thick covering surrounding their DNA and a little bit of cytoplasm.  Bacteria do this to survive in extreme environments like high heat and dryness.  When time is right they can return to their original state

Importance of Bacteria  Decomposers  Nitrogen Fixers- turn N 2 - NH 3  Remove oil slicks  Produce drugs and other substances  Produce vitamin K in your large intestine

Bacterial Diseases  Most bacteria make you sick because of the toxins they produce (Strep)  Some break down the cell for food.(TB)  Vaccine can be given to prevent some bacterial infections.  Antibiotics interfere with bacteria reproduction and growth. (many affect the ribosome structure which then interferes with the protein production of the cell wall)

Controlling Bacteria  Heat sterilization  Chemicals  Food prep and handling