1. Bacteria and Viruses Chapter 18 E. Coli

2. What is a Virus? Nonliving particle—Why not alive? Nonliving particle—Why not alive? No respiration No respiration Doesn’t grow or develop Doesn’t grow or develop Need a host to replicate Need a host to replicate Composed of nucleic acids in protein coat Composed of nucleic acids in protein coat Very small—smaller than bacteria Very small—smaller than bacteria

3. Naming Often named after the disease they cause (poliovirus, rabies virus) Often named after the disease they cause (poliovirus, rabies virus) Sometimes named after the tissue they are found in (adenovirus [causes common cold] found in adenoid tissue) Sometimes named after the tissue they are found in (adenovirus [causes common cold] found in adenoid tissue)

4. Code numbers used to distinguish between similar viruses that infect the same host (ex. T1-T7 for viruses that infect E. coli Code numbers used to distinguish between similar viruses that infect the same host (ex. T1-T7 for viruses that infect E. coli Viruses that infect bacteria are called bacteriophages or phages Viruses that infect bacteria are called bacteriophages or phages

6. Structure Inner core of nucleic acid—can be DNA or RNA Inner core of nucleic acid—can be DNA or RNA Outer coat= Capsid. The proteins found within the capsid determine shape. Outer coat= Capsid. The proteins found within the capsid determine shape. This also determines how the virus infects the cell and what cells can be infected. This also determines how the virus infects the cell and what cells can be infected.

7. Envelope—additional layer outside capsid that some larger viruses have (like human flu virus). Envelope—additional layer outside capsid that some larger viruses have (like human flu virus). Similar to plasma membrane Similar to plasma membrane

9. Attachment Virus protein interlocks with a receptor site on host’s plasma membrane—similar to 2 puzzle pieces attaching Virus protein interlocks with a receptor site on host’s plasma membrane—similar to 2 puzzle pieces attaching Virus attachment proteins are specific to each virus—each virus can only attach to a few kinds of cells (ex. T4 phage can only attach to E. coli and not any other bacteria, human, plant) Virus attachment proteins are specific to each virus—each virus can only attach to a few kinds of cells (ex. T4 phage can only attach to E. coli and not any other bacteria, human, plant)

10. Replication Cycles There are two types: There are two types: The Lytic Cycle The Lytic Cycle The Lysogenic Cycle The Lysogenic Cycle Viruses that replicate by the lytic cycle: Viruses that replicate by the lytic cycle: Have short incubation times Have short incubation times Do not reoccur Do not reoccur Take about 30 mins to make 200 viruses Take about 30 mins to make 200 viruses

11. The Lytic Cycle

12. The Lysogenic Cycle Viruses that replicate by the lysogenic cycle: Viruses that replicate by the lysogenic cycle: Have long incubation times Have long incubation times Reoccur on a regular basis Reoccur on a regular basis Form a provirus Form a provirus

13. The Lysogenic Cycle Provirus  Viral DNA that is integrated into the host cell’s chromosome May not effect host cell’s functioning May not effect host cell’s functioning Reproduces as the host cell reproduces Reproduces as the host cell reproduces

15. Bacteria Tiny (about 1/1000 th of a mm) Tiny (about 1/1000 th of a mm) Found everywhere, on your skin, in the air, on the tables, most anywhere you can think of, there are bacteria. Found everywhere, on your skin, in the air, on the tables, most anywhere you can think of, there are bacteria. Can both hurt and help humans Can both hurt and help humans

16. Bacteria are prokaryotes  Prokaryotes – No nucleus, No membrane bound organelles (no chloroplasts, mitochondria, or vacuoles); organisms are single celled Eukaryotes – Nucleated, membrane bound organelles, can be multicellular or unicellular. Eukaryotes – Nucleated, membrane bound organelles, can be multicellular or unicellular.

17. 2 types  Archea – extreme bacteria. Live in high salt, high temp, high pressure environments, usually found in anoxic conditions Eubacteria – “true” bacteria. Live in more moderate conditions (usually in oxygen) Eubacteria – “true” bacteria. Live in more moderate conditions (usually in oxygen)

18. Bacterial Cell Structure Capsule – sticky outer covering that protects against phagocytosis, toxins and viral infection Capsule – sticky outer covering that protects against phagocytosis, toxins and viral infection Endospore – tough barrier that protects the bacterial chromosome from dehydration when environment lacks water. Endospore – tough barrier that protects the bacterial chromosome from dehydration when environment lacks water.

19. Cell Wall – Provides structure, support, & protects against cell lysis Cell Wall – Provides structure, support, & protects against cell lysis  Flagella – Whip like structure that spins to allow bacteria to move

20. Pili – Smaller hair like projections on the surface of bacteria that allow it to stick to a surface. Pili – Smaller hair like projections on the surface of bacteria that allow it to stick to a surface. Plasmid – small segment of genetic material (contains extra genes) Plasmid – small segment of genetic material (contains extra genes)

22. Bacterial Reproduction:  Reproduce asexually - They don’t need genetic material of other bacteria (no gametes)  Binary Fission – similar to mitosis, chromosome doubles, and then is split between the two cells.