1. Viruses! Viruses are microscopic particles that
invade the cells of plant, animals, fungi, and bacteria.
AIDS Virus
Bacteriaphage

2. Comparison of structures of viruses and animal cells.

3. In many viruses, DNA is the genetic material. Other viruses have RNA.
A virus is not a cell. A typical virus is composed of a core of genetic material surrounded by a protein coat. The protein coat protects the virus and enables it to invade its host cell.
In many viruses, DNA is the genetic material. Other viruses have RNA.
Viruses are parasitic and can reproduce only inside the cells of their host. This makes viruses very different from bacteria and protists.
AIDS Virus

4. Virus: Living or Not?
There has been an ongoing debate among scientists as to whether or not viruses are alive or not alive. Viruses lack three essential features of living things:
1. They are not made of cells
2. They cannot make proteins by themselves
3. They cannot use energy
Even though viruses can reproduce they are only able to so when inside living cells. because they cannot reproduce on their own most scientists classify them as non - living things.
Viral genetic material has room for only a few genes. Usually they are only genes that code for the protein coat and for enzymes that enable to virus to take over the cell.

5. Virus Reproduction
How Viruses Work Video
(2:25)
All viruses reproduce by taking over the reproductive machinery of a cell.

6. Differences Between Lytic
and Lysogenic Cycles
In the Lytic Cycle:
Viral DNA destroys Cell DNA, takes over cell functions and destroys the cell.
The Virus replicates and produces progeny phages.
There are symptoms of viral infection.
Virulant viral infection takes place.
In the Lysogenic Cycle:
Viral DNA merges with Cell DNA and does not destroy the cell.
The Virus does not produce progeny.
There are no symptoms of viral infection.
Temperate viral replication takes place.

7. Virus Reproduction

8. The reason HIV is such a dangerous virus is because it has the ability to take over the white blood cells!
HIV waits for a white blood cell to attack it, then it takes over the white blood cell and makes it into a virus making factory.
The effect of this is that other viruses can now take over your body and kill you because your defenses have been taken down by the HIV.

10. The most effect defenses we have against viral diseases is vaccination.
Vaccines Video (3:22)

11. #2 since viruses actually enter healthy cells,
Viruses cause serious human diseases in addition to AIDS, such as measles and influenza.
Viral diseases are much more difficult to treat than bacterial diseases. This is true for a few reasons.
#1 most antibiotics that are used on bacteria disrupt the bacteria’s cell wall or proteins inside the bacteria.
Since a virus has no cell wall or inner proteins it is immune
to those medicines.
#2 since viruses actually enter healthy cells,
it is hard to find them.
Not only is it difficult to find them but it is hard to kill them without also killing the cells they are living in.

13. Herpes

14. Understanding Bacteria VIDEO (4:00 min)

15. Although you do not see them, bacteria are everywhere and affect your life in many ways.
large intestine: bacteria synthesize (make) vitamin K, which is essential to good nutrition
your mouth: may cause cavities in your teeth
diseases: cholera, typhus, pneumonia, sexually transmitted diseases, and tuberculosis

16. Key Shapes Cocci – round Bacilli – rod Spirilli – spiral
Strepto – chains
Staphylo – clusters
Diplo - pairs
prefix

17. Most species of bacteria are one of 3 different shapes:
Ex. Bacillus anthracis
Ex. streptococci
Ex. Treponema pallidum = syphilis

18. Spiral (called spirilli)
Ex. Treponema pallidum = syphilis

20. Bacteria are either Gram-positive or Gram-negative.
Gram Staining
A series of dyes is added to a sample of bacteria as a microscope slide is being prepared during the process of gram staining.
Bacteria are either Gram-positive or Gram-negative.
The difference between Gram-negative and Gram-positive bacteria is important in diagnosing and treating diseases caused by bacteria.

21. Bacteria such as Streptococcus pneumoniae stain purple during Gram staining and are known as Gram-positive bacteria.

22. Bacteria such as E. coli stain pink during Gram staining and are known as Gram-negative bacteria.

23. Bacteria Reproduce Rapidly
Bacteria do not undergo mitosis or meiosis. Instead, the bacterium first duplicates its DNA so that there is enough DNA for two cells.
Then the bacterium splits into two identical cells. Each cell receives one molecule of DNA and some cytoplasm.

24. Some bacteria are able to divide as many as 5 times in one hour.
1 -2 – 4 – 8 – 16 – 32 – 64 – 128 – 256 – 512 – 1,024 –
Some bacteria are able to divide as many as 5 times in one hour.
If you were to place a single bacterium into a culture dish containing an abundant (lots) supply of food, you could find more than 600,000 bacteria in the dish after only 4 hours.
After 6 hours, the bacterial population of the dish could reach 476 million!
16,777,216 – 33,554,432 – 67,108,864 – 134,217,728
4,096 – 8,192 – 16,384 – 32,768 – 65,536 – 131,072
- 8,388, ,194, ,097, ,048, , ,144 -

25. Sometimes bacteria do have a form of sex called conjugation.
One bacterium reaches out to another using a thread-like structure called a pilus.
The first bacterium transfers part of its DNA to the other bacterium through the pilus. By this exchange, bacteria can quickly create or pass along new traits that help them adapt to different environments.

26. How Bacteria Obtain Nutrition
A major reason for the success of bacteria is the wide variety of foods they can use.
Example:
A glass of milk left out of the refrigerator provides a wealth of food for bacteria.
Within hours, bacteria colonize the milk and break down its supply of sugar, causing the milk to curdle.

27. Autotrophs and Heterotrophs
Some bacteria are autotrophs.
Autotrophic organisms make their own food by using simple molecules.
Most bacteria cannot make their own food and are therefore heterotrophs.
Many feed on dead animals and animal wastes; dead plants; and fallen leaves, branches, and fruit.

28. Helpful Bacteria Fix nitrogen Recycle nutrients
Used to make certain foods and
aid in digestion
yogurt, olives, sauerkraut, pickles
Clean up oil and toxic spills - video (.19)
Used to make antibiotics, vitamins, and drugs
Used as natural pesticides

29. Bacteria Are Fighting Back
Fight Back video (2.30)
Until the late 1980s, many scientists thought that we had conquered most infectious bacterial diseases and that the rest would soon be controlled.
But, bacteria reproduce rapidly and mutate. And, they become resistant to the drugs we use against them.