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Disease Causing Agents and Natural Selection

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Presentation on theme: "Disease Causing Agents and Natural Selection"— Presentation transcript:

1 Disease Causing Agents and Natural Selection

2 3.4.3 Explain how various disease agents (bacteria, viruses, chemicals) can influence natural selection.

3 Antibiotic Resistance
Antibiotics kill bacteria. Continued use will cause some of the bacteria to mutate and survive. Bacteria lives on.

4 Pesticide Resistance Pesticides are used to kill insects on crops.
Continued use will cause some insects to become immune. The insects live on.

5 Human Immunity Two types Active Immunity Passive Immunity

6 Active Immunity You produce the antibodies
Your body has been exposed to the antigen in the past either through: Exposure to the actual disease causing antigen – You fought it, you won, you remember it Vaccine- planned exposure to a form of the antigen that has been killed or weakened – You detected it, eliminated it, and remember it

7 Active Immunity ~White Blood Cells~
T- Cells-kill infected cells; some help B-Cells produce antibodies B- Cells- make antibodies Memory Cells- quickly recognize pathogens if encounter again.

8 Immunity New particles take longer to identify, and a person remains ill until a new antibody can be crafted Old particles are quickly recognized, and a person may never become ill from that invader again. This person is now immune.

9 How long does active immunity last?
It depends on the antigen Some disease-causing bacteria mutate into new forms that our body doesn’t recognize, requiring annual vaccinations, like the flu shot Booster shot - reminds the immune system of the antigen Others last for a lifetime, such as chicken pox

10 Think the flu is no big deal?
Think again… In 1918, a particularly deadly strain of flu, called the Spanish Influenza, spread across the globe It infected 20% of the human population and killed 5%, which came out to be about 100 million people

11 Passive Immunity You don’t produce the antibodies
A mother will pass immunities on to her baby during pregnancy These antibodies will protect the baby for a short period of time following birth while its immune system develops Lasts until antibodies die

12 Immune Disorders ~Allergies~
Immune system mistakenly recognizes harmless foreign particles as serious threats Launches immune response, which causes sneezing, runny nose, and watery eyes Anti-histamines block effect of histamines and bring relief to allergy sufferers

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