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

http://candaceb.myweb.uga.edu/Binary%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 livingorganisms, 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 121oC with high pressure steam.

ANTHRAX ENDOSPORE Bacillus anthracis

Impact of Prokaryotes on Humans

Fill in Chart Identifying Agents if Disease pages 11-12 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 andother 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.