BACTERIA AND VIRUSES

The Good: BACTERIA

•Are Prokaryotic Unicellular organisms•Has a role in maintaining health by

inhabiting our intestine to aid in digestion and producing vitamins that our bodies need

•Remove waste from water•Used in medicine

The Bad: Bacteria• BACTERIA CAN CAUSE

DISEASE• ARE TREATED WITH

ANTIBIOTICS • Tooth Decay

• Tetanus

• Diphtheria

The Ugly: Viruses• Non living “organisms”

that can only reproduce inside a living cell

• Unique Structure

• Causes disease specific to a host

Question..What is the most common threat to a host

organism posed by an invading virus?A Production of viral fluids in the

bloodstreamB Fermentation of acids in the digestive

systemC Destruction of cells by viral

reproductionD Stimulation of muscle tone in the heart

 

The Ugly: Viruses ContinuedCapsid/Head

Fiber Tails

Base Plate

QuestionThe photograph shows a

virus attacking a human T cell (immune cell). Which disease could result if many T cells are destroyed in this manner?

A AIDSB TuberculosisC Chicken poxD Multiple

sclerosis

The Ugly: More about viruses

•Invade other cells by attaching to a cell and injecting their genes or by being swallowed up by the cell.

•Responsible for many human diseases

•Can result in death

The Ugly• Rabies

• Smallpox

• AIDS

Terms

• Microorganism

▫Usually a bacterium, virus, or fungi

▫play an important role in many ecosystems

▫Life cycles of microorganisms are studied in order to better understand diseases

• Pathogen

▫A bacterium, virus, or other microorganism that can cause disease

AIDS:

Acquired immune deficiency syndrome

HIV:

Human Immunodeficiency Virus

What do they stand for?

Glycoprotein: binds to receptor molecules on the host cell membraneViral Envelope: made of 2 layers of fatty acidsReverse transcriptase: Makes DNA from RNACapsid: Protective protein coat

Basic facts about HIV/AIDS

•HIV is a retrovirus•HIV is the virus that causes AIDS•HIV attacks T-cells (specifically called

CD4 cells)•HIV/AIDS is treatable, but not curable•You can’t tell by looking if a person is

living with HIV, the only way to know is by taking an HIV antibody test.

Origin•descendant of a Simian Immunodeficiency

Virus because certain strains of SIVs bear a very close resemblance to HIV-1 and HIV-2, the two types of HIV.

•Sooty mangabey (also known as the White-collared monkey)

How could HIV have crossed species?

• The 'hunter' theory▫chimps being killed and eaten or their blood

getting into cuts or wounds on the hunter• The oral polio vaccine (OPV) theory

▫ journalist Edward Hooper suggests that HIV can be traced to the testing of an oral polio vaccine called Chat, given to about a million people in the Belgian Congo, Ruanda and Urundi in the late 1950s. To be reproduced, live polio vaccine needs to be cultivated in living tissue, and Hooper's belief is that Chat was grown in kidney cells taken from local chimps infected with SIVcmz. This, he claims, would have resulted in the contamination of the vaccine with chimp SIV

•The contaminated needle theory

▫likely that one single syringe would have been used to inject multiple patients without any sterilization in between. This would rapidly have transferred any viral particles (within a hunter's blood for example) from one person to another

How could HIV have crossed species?

Four of the earliest known instances of HIV infection are as follows:

•A plasma sample taken in 1959 from an adult male living in what is now the Democratic Republic of the Congo.

•A lymph node sample taken in 1960 from an adult female, also from the Democratic Republic of the Congo.

•HIV found in tissue samples from an American teenager who died in St. Louis in 1969.

•HIV found in tissue samples from a Norwegian sailor who died around 1976.

The 4 Fluids

•Blood•Semen•Breast Milk•Vaginal Fluids

These are the four fluids that transmit HIV. The key to protecting yourself from infection is to avoid these four

bodily fluids.

Transmitting HIV

HIV is transmitted when one or more of the four fluids is transferred from one person to another. The most common ways HIV is transmitted is by:

•Unprotected sex•Sharing needles•Breastfeeding from infected mother to baby

HIV is not spread by casual contact.

• It dies quickly outside the body and is easily killed by soap and by common disinfectants such as bleach.

• There is no risk of HIV infection from: • donating blood• mosquito bites• toilet seats• shaking hands• hugging• sharing eating utensils• food or objects handled by people with HIV or AIDS• spending time in the same house, business, or public

place with a person with HIV/AIDS.

Preventing HIV:Sharing Needles/Breastfeeding

Needles should never be shared. When getting tattoos or piercings, make sure that new needles and new ink bottles are used.

Injection drug users should never share works. Works can be cleaned using bleach and water.

Mothers living with HIV should not breastfeed babies; prenatal care can help reduce the chance that babies of HIV-infected mothers are born with HIV.

HIV Transmission Activity

•On separate sheet of paper, put your name, date, class period. Copy table below

Person’s Name Infected?

1

2

3

Total students in class:Total that were “infected”:

Percent that “got infected”:

Follow-Up Questions•1. Did every person in the room become

infected? Why/why not?•2. If we continued to do this activity, would

everyone eventually get HIV? Explain.•3. Name at least two other viral diseases

besides HIV/AIDS. •4. List 4 fluids that can transmit HIV.•5. Discuss at least two ways the spread of

HIV/AIDS can be prevented.•6. What is the difference between HIV and

AIDS? •7. What does a person with HIV look like?

Can you recognize someone with this virus?