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Viruses, Bacteria & Diseases

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Presentation on theme: "Viruses, Bacteria & Diseases"— Presentation transcript:

1 Viruses, Bacteria & Diseases

2 Viruses Viruses are NOT cells. A virus is an infectious agent made up of: a core of nucleic acid (RNA or DNA) a protein coat (capsid) Genetic material carries information for multiplication Hijacks biochemical machinery of host cell to carry these processes out So…viruses are NOT LIVING

3 Characteristics of life
CELL VIRUS Made of cells YES NO Obtain & use energy Grow & develop Only inside a living cell Reproduce Respond & adapt Contain RNA or DNA

4 Re-Cap Viruses are NOT ALIVE. Viruses do not: Viruses do: Grow
Have homeostasis Metabolize Viruses do: Infect cells and use the cell to make more viruses Cause disease in many organisms

5 Structure of a virus Envelope (part of the protein coat)
Capsid (part of the protein coat) Nucleic acid (either DNA or RNA) NUCLEIC ACID CAPSID

6 Retrovirus A virus that contains RNA instead of DNA
CAPSID A virus that contains RNA instead of DNA Human Immunodeficiency Virus (HIV) is a retrovirus HIV causes AIDS ENVELOPE RNA

7 Bacteriophage A virus that only infects bacteria CAPSID HEAD DNA

8 Ticking time bombs . . . Viruses do not reproduce by themselves. They invade a living cell and let the cell do the work for them.

9 Lytic Cycle The viral infection that rapidly kills the host cell is the lytic cycle.

10 Cycle Illustration 1 2 3 4 5

11 Lysogenic Cycle The viral infection that enters a cell, remains harmless for a period of time (sometimes years), and then becomes harmful later is called the lysogenic cycle.

12 Lysogenic Cycle In the lysogenic cycle, the virus reproduces by first injecting its genetic material, indicated by the red line, into the host cell's genetic instructions.

13 Role of viruses All viruses act like parasites, harming the host cell.
Viruses cause disease in every kind of organism—animals, plants, fungi, protists, and bacteria.

14 Some viral diseases HIV Measles Smallpox Influenza Chicken pox
Common cold Herpes Warts Mononucleosis Mumps

15 HIV A retrovirus Infects human helper T-cells, which are associated with the immune system. Modes of transmission: Sexual contact with an infected person Sharing needles with an infected person Blood transfusions (rare) Breast feeding Etc.

16 HPV Human Papilloma Virus Causes warts
Most common STD in the United States 80% of women by the age of 50 will have acquired some strain of genital HPV. HPV vaccine

17 Influenza (flu) Symptoms: body aches, fever, coughing, runny nose, fatigue, usually lasting about a week. Mode of transmission Airborne (air droplets) People still die from influenza.

18 Viral diseases usually cannot be cured, but many can be prevented by
Good hygiene Immunization

19 Bacteria are Prokaryotes. Prokaryotic Cells:
Have no nucleus Do not have membrane bound organelles Are very small Often have a flagellum for movement

20 Shapes of bacteria Bacteria are classified according to their shape:
Round is called cocci Rod shaped is called bacilla Spiral shaped is called spirilla

21 Where do they live? Bacteria are found in all environments

22 Role of bacteria Some bacteria are helpful Some bacteria are harmful
E. coli Yeast V.streptococci Lactobacillus Some bacteria are harmful S. pyogenes S. aureus Y. pestis

23 Streptococcus Causes strep throat, pneumonia, and other infections.
Named based on the shape and orientation of the bacteria.

24 Staphylococcus Cause of staph infections that occur on the skin or in wounds. (ex. MRSA) But, Certain types of staph reside normally on the skin.

25 Diphtheria Swelling of the upper respiratory tract DPT Vaccine
Can also infect skin cells.

26 How do bacteria cause disease?
The release toxins that interfere with normal activity.

27 Prevention/Cure Vaccines to prevent.
Antibiotics to cure (pennicillin, amoxycillin, etc).

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