Viruses and Bacteria Chapter 18 Notes to replace Section Assessments and Chapter Reviews Summer School CP Biology

What is a Virus Viruses are non living cellular material that requires a host to survive. Very very small Contain an inner core of RNA or DNA called a Capsid that contains genetic instructions that can only work if injected into a host cell. There are 4 different shapes. Draw and label each shape on pg Enveloped, Helical, Polyhedral and Bacteriophage

Viral Attachment and Replication Viruses are host specific and must find the correct receptor point on the plasma membrane of the host cell. (Similar to a lock opened by a specific key) Replication occurs once the Virus injects the host cell with it’s genetic information. Draw the lytic cycle on page 550 and label the steps.

HIV HIV is a virus that attacks Human white blood cells. It is a retrovirus (RNA in virus) Can have a dormancy of many years A person infected with the HIV virus will die from some other illness because the HIV attacks and kills the white blood cells (which attack and kill pathogens in the body) Some viruses cause cancer or tumors. Warts are an example of a tumor created by a Virus.

Bacteria Archebacteria- Ancient bacteria that live in very extreme conditions on earth. Called Extremeophylls (lover of extreme conditions) Eubacteria- Use energy and have nutritional needs (heterotrophs) Some Eubacteria can photosynthesize and some can chemosythesize (hydrothermal vents)

Structure of a bacteria No membrane bound organelles (prokaryotic) Draw and label the parts of the typical bacteria from page 557. Bacteria reproduce by fission (splitting into two genetically identical halves) some can do this every 20 minutes Time in Minutes # of Bacteria min (1 hour) (2 hrs) 140

Bacterial shapes 3 basic shapes of bacteria: Spherical, Rodlike and Spiral Draw the picture of each from page 556 Bacteria can be aerobic (Require Oxygen) or anaerobic (Do not require Oxygen) Some bacteria can survive for a very long time by creating an Endospore which contains the Bacteria’s DNA and a small amount of its cytoplasm. The endospore can withstand extreme temperatures and conditions until the conditions become better suited for the spore to germinate and become a bacteria again.

Bacteria’s importance Benefits of Bacteria are: Nitrogen Fixing (in essence it helps fertilize for plants by taking Nitrogen from the atmosphere and making it available to life) Bacteria are a primary decomposer that recycles nutrients. Many foods and medicines we eat and use rely on Bacteria such as Swiss cheese and Bacteria We can splice genes into a bacteria to produce products like human insulin Bioremediation using bacteria to break down pollutants in the environment

Bacterial Diseases Many Bacteria cause infections and diseases such as Strep throat, Staph infection, Tetanus and cavities These can usually be treated with antibiotics that attack the specific type of bacterial cell wall or Capsid it has.