Bacterial Reproduction Can reproduce at a phenomenal rate if conditions are favorable. The cells divide by a process called binary fission. –Copy their DNA and divide nary%20Fission.html HOW FAST? In 24 hours, one cell could give rise to a bacterial colony equivalent in mass to 15,000 humans. But, few can sustain exponential growth for very long. Why?

Bacterial Nourishment: obtaining energy and carbon Prokaryotic evolution “invented” every type of nutrition we observe in all living organisms, plus some modes unique to prokaryotes. Energy source examples: H2S and NH4 (deep ocean hot vents) Very common In prokaryotes

A unique feature of prokaryotes: Endospores Endospores (in some prokaryotes): –Specialized “resting cells” –Can survive extended periods of very harsh conditions Lack of water/nutrients Extreme temperatures Most poisons –Outer cell produces protected inner endospore –Outer cell may disintegrate, but endospore can survive – Some can remain for centuries. –Autoclaves kill endospores by heating to 121 o C with high pressure steam. ANTHRAX ENDOSPORE Bacillus anthracis

Impact of Prokaryotes on Humans Fill in Chart Identifying Agents if Disease pages in your U.P. DISEASE-CAUSING BACTERIA Some bacteria cause disease in humans by producing poisons Exotoxins: poisonous proteins secreted by bacteria cells Example: botulism, staph infections Often cause vomiting and diarrhea Endotoxins: chemical components of cell wall of bacteria Example: food poisoning (salmonella), typhoid fever Often cause fever, aches, drop in BP Ways to prevent bacterial infections: Sanitation Antibiotics Education Haemophilus bacteria on human skin can cause pneumonia and other lung infections

Power of Antibiotics : How can you measure effectiveness against bacteria? Zone of Inhibition- area in which the growth of bacteria is prevented or inhibited by an antibiotic or other substance. This zone can be measured. Circle the zones of inhibition with your pen.