1. Viruses and Bacteria

2. What do these diseases have in common?
Mumps
Hepatitis B
Measles
Polio

3. It looks alive, acts alive… but it’s not alive!
Viruses are not living things. They differ from living things in several ways.
They need to be inside a living organism to reproduce themselves.
Outside the cell, they have no metabolism.
They do not have cell parts. (i.e. nucleus, mitochondria, etc.)
Most viruses are composed of only a nucleic acid (DNA or RNA) inside a protein capsule.

4. Virus Structures Protein capsid DNA (or RNA) Tube Tail Fiber
Tail Fiber

5. Viral Reproduction In order to reproduce:
A virus attaches to a host cell.
The virus injects the cell with its nucleic acid.
The viral nucleic acid commands the cell to make more viral protein and nucleic acid.
The cell then ruptures, releasing hundreds of new viruses.

6. No, they aren’t from the 70’s.
Retroviruses.
These are viruses that store their genetic information as RNA.
Ex. HIV (Human Immunodeficiency Virus.)

7. How it works……

8. Kingdoms Eubacteria and Archaebacteria
Bacteria are living, unicellular prokaryotes.
Cover nearly every square centimeter of the Earth.
Are heterotrophs or autotrophs (most use chemosynthesis).
Types of Bacteria are classified based on their shape, type of cell wall, and movement.
Bacteria have three basic shapes:
Bacilli – rod-shaped
Cocci – spherical
Spirilla – spiral

9. Structure of a Bacteria
Cell membrane
Cell wall
DNA
Ribosomes

10. Gram staining is used to differentiate types of Eubacteria.
Eubacteria have peptidoglycan and certain specialized lipids in their cells walls that are not present in Archaebacteria.
Gram staining is used to differentiate types of Eubacteria.
Those having thick cell walls will absorb more of the dye and appear dark purple (Gram positive).
Those having thinner cell walls will absorb less of the dye and appear pink (Gram negative).

11. Bacteria Growth and Reproduction
Bacteria reproduce in 2 main ways:
Binary fission - bacteria grows to double its original size, copies its DNA and divides, producing 2 identical cells.
Conjugation - a hollow bridge is formed between 2 bacteria, genes are transferred from one cell to the other.
Creates genetic diversity within a population.
Spore formation - when conditions are unfavorable (lack of food, drought) a bacterium encloses its DNA and part of its cytoplasm in a spore.
When conditions are better, the spore will germinate, and the bacterium will continue to grow.

12. Dangers of Bacteria Break down cells and tissues for food.
Ex. Tuberculosis (destroys lung tissue).
Release toxins (poisons) that travel through the body.
Ex. Streptococcus releases toxins into the blood stream causes strep throat and scarlet fever.

13. We’re not all bad….
Bacteria are most widely known for causing diseases such as strep throat, tetanus, meningitis, and tuberculosis.
However, most bacteria are very useful:
E. coli helps us digest our food.
Many are important decomposers in our ecosystem.
Rhizobium provides plants with nitrogen.
A few bacteria are used to clean up small oil spills in the ocean.

14. Vaccinations
A weakened or killed form of the pathogen (virus/bacteria) is used to stimulate the production of antibodies.
However, viruses and bacteria have very high reproductive rates, which result in many mutations.
Thus, viruses and bacteria evolve quickly, often requiring a different vaccine every year.
Ex. Influenza vaccinations.

15. There are two types of vaccines (immunities).
Active - a person is injected with the actual pathogen, immune cells make their own antibodies against the disease.
Immunity is permanent.
Passive - person is injected with antibodies that fight the disease
Immunity is temporary.

16. Antibiotics Antibiotics block the growth and reproduction of bacteria.
Used to treat bacterial infections.

17. Diseases such as Scrapie (in sheep) and Mad Cow Disease are not caused by bacteria or viruses. What could cause them?

18. Prions Contain only protein.
Cause disease by forming protein clumps which then induce normal proteins to become Prions.
The build up eventually damages nerve tissue.