MICROBIOLOGYPathogens and Viruses

Prokaryotevs.

Eukaryote

Prokaryotes (Bacteria)

Fossil evidence shows that bacteria have been on the earth for over 3.5 billion years

Three major shapes› Cocci (round)› Bacilli (rod-like)› Spirilla (spiral)

HARMFUL BACTERIA Some bacteria are pathogens (disease

causing) Some bacteria can make endospores,

which allow bacteria to survive long periods of time (even in bad conditions)

Diseases caused by bacteria:• Pneumonia•Strep throat•Ear infections•Salmonella•Cholera

•E. coli infections• Lyme•Tetanus•Tuberculosis• Leprosy

Lyme

Strept throat

Leprosy

HELPFUL BACTERIA In your intestine, E. coli help to

digest food Used to make yogurt Can be used to degrade oil and

toxic waste spills Used to make certain medicines Used as “gene” factories Help plants fix nitrogen Major decomposers

Decomposition over 2 weeks

Legumes with nitrogen fixing bacteria in their roots

KILLING BACTERIA Antibiotics- drugs that kill bacteria by

blocking growth or reproduction› Antibiotics do NOT kill any viruses so

they do not cure the common cold or flu

› Some bacteria are now resistant to antibiotics (ex. MRSA)

› We must always take antibiotics as prescribed!

Sterilization – destroying bacteria by heating or with chemicals

Bacilli Cocci

Spirilla

VIRUSES Viruses are particles made up of

nucleic acid (DNA and/or RNA), protein, and sometimes lipids.

Viruses are NOT living because they cannot reproduce by themselves.

All viruses enter (infect) living cells and once inside of a cell, they make more viruses.

All viruses are pathogens. Viruses are thought to have evolved

from pieces or fragments of cells.

VIRUS STRUCTURE

Viruses have a core of genetic material surrounded by a capsid (protein coat)

They are much smaller than bacteria and animal cells.

They come in many shapes.

VIRAL DISEASES Polio AIDS Influenza (the flu) Yellow fever Rabies Common cold Some cancers like cervical cancer Measles Small pox

Small Pox

Measles

Polio

Herpes

Pathogen Poster

VIRAL INFECTIONS

All cells can be infected by viruses including bacteria, animals, and plants.

Bacteriophage – a virus that infects a bacterial cell

There are two main methods of infection:1.Lytic2.Lysogenic

Bacteriophage (virus) infecting a bacterium

LYTIC CYCLE Viruses inject their genetic

material (DNA or RNA) into the host cell.

This genetic material gives instructions to make viruses.

The viruses are released by causing the cell to burst (lyse), which kills the cell.

LYSOGENIC CYCLE A virus injects its genetic material

(DNA or RNA) into the host cell. The virus’s genetic material is

mixed in with the host DNA. Viral DNA can stay embedded in

the host DNA for long periods of time.

Sometimes, the viral DNA will instruct new viruses to be made and the lytic cycle begins.

VACCINES Vaccines – made from weakened or

“killed” viruses Vaccines stimulate the immune

system to fight a specific disease Vaccines help prevent viral and

bacterial diseases from developing, but cannot help someone already infected

Examples include: HPV, MMR, Hep A

PRIONS

Prions - possibly infectious proteins that can change brain proteins causing brain damage

Diseases caused by prions progress rapidly and are almost always fatal

Diseases caused by prions include:

› Mad Cow Disease› Creutzfeldt-Jakob Disease (CJD)

Creutzfeld-Jakob Disease

Spread the word, not the germs!1) WASH your hands when they are dirty and BEFORE eating. 2) DO NOT cough into your hands. 3) DO NOT sneeze into your hands. 4) DO NOT put your fingers into your eyes, nose, or mouth.

Regular soap and water are best. Antibacterial soaps are not necessary if you have spent enough time (at least 20 seconds) cleaning your hands with regular soap and water.

(Source: www.henrythehand.com)