Brain Stretch 5

Crazy Scientist’s ExperimentIn 1928, Sir Alexander Fleming was studying Staphylococcus bacteria growing in culture dishes. He noticed that a mold called Penicillium was also growing in some of the dishes. A clear area existed around the mold because all the bacteria that had grown in this area had died. In the culture dishes without mold, no clear areas were present.

Fleming hypothesized that the mold must be producing a chemical that killed the bacteria. He decided to isolate this substance and test it to see if it would kill bacteria. Fleming transferred the mold to a nutrient broth solution. This solution contained all the materials the mold needed to grow. After the mold grew, he removed it from the nutrient broth. Fleming then added the nutrient broth in which the mold had grow to a culture of bacteria. He observed that the bacteria died.

1. Identify the problem.

2. What was Fleming’s hypothesis?

3. How was the hypothesis tested?

4. Should the hypothesis be supported or rejected based on the experiment?

5. This experiment lead to the development of what major medical advancement?

Infectious and Noninfectious DiseasesAn infectious disease is an illness that is caused by pathogens that enter the body

through direct contact. Pathogens are disease-causing organisms. Infectious diseases can spread by direct physical contact or through indirect contact.

Noninfectious diseases are illnesses that are not caused by pathogens. For example, heart disease is not caused by coming into contact with a person who has heart

disease. Instead, heart disease can result from hereditary factors, improper diet, smoking, and other risk factors.

Indicate in the second column of the table if the disease is an infectious disease.Disease Infectious (yes or no)Allergy

Cystic Fibrosis

Strep Throat

Cancer

Common Cold

Diabetes

STDs

Pneumonia

http://www.dnatube.com/video/4330/White-Blood-Cell-Chases-Bacteria

Math ConnectionBacteria live in groups called colonies. Colonies are usually circular. The diameter (distance across) of a

particular bacterial colony is 8 mm. The circumference of a circle is equal to (3.14) times

the diameter (C= d). What is the circumference of the colony?

Science ScrambleFinish the sentence by unscrambling the italicized word.

1. Harmful bacteria in food can be killed with heat during a process called nizutaspitorea.

2. eicVancns can prevent some bacterial infections. 3. Whiplike tails call elalgalf help bacteria move.4. Rod-shaped bacteria are called cabllii.5. Sphere-shaped bacteria are called ioccc.6. siFnios is the simplest form of asexual reproduction.7. nPclnielil is a well-known antibiotic that works by

preventing bacteria from making cell walls.8. An organism that uses oxygen for respiration is an

aeeobr.

What have you learned so far from your classmates’ presentations? Write a paragraph summarizing your new-found knowledge about

bacteria.

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