Natural Selection Antibiotic Resistance

What is Antibiotic Resistance? Watch the Video Clip about tuberculosis in Russian prisons Why is the Russian prison system considered “ground zero” in the fight against TB?

Virus vs. Bacteria A virus is non-living, does not have organelles, and needs a host cell to reproduce Bacteria are alive, have ribosomes, and can reproduce on their own

Antibiotics Substances that kill disease causing bacteria Fifty years ago, scientists thought that antibiotics had eradicated certain bacterial infections Now, we are seeing an increase in infectious disease

What is happening? When antibiotics are used, MOST of the bacteria are killed. Some of the bacteria have mutated and can survive even when the antibiotic is taken They are “resistant” to the antibiotic

Mutation Review How does a mutation occur? –The DNA sequence is changed in some way –An error occurs during Replication Transcription Translation –When the bacteria reproduce, this mutation is passed on to the new bacteria

Natural Selection The “resistant” bacteria are the only bacteria to survive after using antibiotics They reproduce rapidly! This creates an entire colony of resistant bacteria that will not be killed by antibiotics

Natural Selection means the survival of the “fittest” What does “fittest” mean? –Those organisms that can survive and reproduce –Adapted to the environment The resistant bacteria are the “fittest” and survive and reproduce

If the weakest bacteria are killed first, and you stop taking your antibiotics after five days of a ten day course, what do you predict will happen to the population of bacteria in your body?

Antibiotic Resistance Activity Follow the procedure on your lab paper to simulate what happens when antibiotics are not taken as prescribed Record your data in Table 1 and graph the data when you are finished Complete the analysis questions in your lab notebook