Podcast
Questions and Answers
Antibiotics primarily target which type of infections?
Antibiotics primarily target which type of infections?
- Bacterial (correct)
- Parasitic
- Viral
- Fungal
What is the primary mechanism by which most antibiotics work?
What is the primary mechanism by which most antibiotics work?
- Disabling a necessary component of bacterial cells not found in animal cells (correct)
- Enhancing the immune response to target bacteria
- Stimulating the growth of beneficial bacteria
- Directly attacking the nucleus of bacterial cells
Which characteristic of bacteria allows them to reproduce rapidly via binary fission?
Which characteristic of bacteria allows them to reproduce rapidly via binary fission?
- Multicellular structure
- Complex nucleus
- Prokaryotic cell structure (correct)
- Slow metabolic rate
Tetracycline is a common antibiotic. How does it work?
Tetracycline is a common antibiotic. How does it work?
Why are sulfa drugs able to selectively target bacteria without harming human cells?
Why are sulfa drugs able to selectively target bacteria without harming human cells?
What proportion of all infectious diseases are caused by bacteria?
What proportion of all infectious diseases are caused by bacteria?
What is the significance of moldy bread being used in ancient Egypt?
What is the significance of moldy bread being used in ancient Egypt?
Alexander Fleming's discovery of penicillin is an example of what?
Alexander Fleming's discovery of penicillin is an example of what?
What type of scientific source is Alexander Fleming's research article about his discovery of penicillin?
What type of scientific source is Alexander Fleming's research article about his discovery of penicillin?
What is considered to be the greatest medical advancement during the 20th century?
What is considered to be the greatest medical advancement during the 20th century?
When was the first instance of Staph. aureus resistance to penicillin observed?
When was the first instance of Staph. aureus resistance to penicillin observed?
In the context of antibiotic resistance, what does MRSA stand for?
In the context of antibiotic resistance, what does MRSA stand for?
What is the significance of Vancomycin in the treatment of bacterial infections?
What is the significance of Vancomycin in the treatment of bacterial infections?
By the 2000s, what was a significant trend observed in clinics regarding antibiotic resistance?
By the 2000s, what was a significant trend observed in clinics regarding antibiotic resistance?
In 2019, what was the global impact of antibiotic-resistant bacterial infections?
In 2019, what was the global impact of antibiotic-resistant bacterial infections?
On an agar plate used to test antibiotic susceptibility, what does a clear area around a white circle indicate?
On an agar plate used to test antibiotic susceptibility, what does a clear area around a white circle indicate?
If a bacterial culture on an agar plate shows no zone of inhibition around an antibiotic disc, what does this indicate about the bacteria?
If a bacterial culture on an agar plate shows no zone of inhibition around an antibiotic disc, what does this indicate about the bacteria?
What is the fundamental explanation for how bacteria develop resistance to antibiotics?
What is the fundamental explanation for how bacteria develop resistance to antibiotics?
What defines evolution in biological terms?
What defines evolution in biological terms?
What is a population in a biological context?
What is a population in a biological context?
What primarily determines heritable traits in an organism?
What primarily determines heritable traits in an organism?
How are new traits typically introduced into a population?
How are new traits typically introduced into a population?
Which of the following describes a mutation?
Which of the following describes a mutation?
Do all new traits that appear in a population spread and lead to evolution?
Do all new traits that appear in a population spread and lead to evolution?
What two conditions are essential for evolution to occur?
What two conditions are essential for evolution to occur?
In a scenario where butterflies of two different colors share a habitat with no selective advantage for either color, what would you expect to happen to the frequency of the colors over time?
In a scenario where butterflies of two different colors share a habitat with no selective advantage for either color, what would you expect to happen to the frequency of the colors over time?
What would be the likely outcome for a butterfly population if a new predator is introduced that exclusively eats yellow butterflies?
What would be the likely outcome for a butterfly population if a new predator is introduced that exclusively eats yellow butterflies?
What is natural selection?
What is natural selection?
What role do selective pressures play in evolution?
What role do selective pressures play in evolution?
How can environmental factors drive natural selection?
How can environmental factors drive natural selection?
If the original population of tree frogs were bright green, which process is most responsible for one lineage becoming Grey?
If the original population of tree frogs were bright green, which process is most responsible for one lineage becoming Grey?
True or false: An individual can evolve.
True or false: An individual can evolve.
Which of the following would be considered environmental factors that drive natural selection?
Which of the following would be considered environmental factors that drive natural selection?
Why can populations of bacteria evolve so quickly?
Why can populations of bacteria evolve so quickly?
If a certain type of bacteria is present in the human body, and they have a mutation allowing for antibiotic resistance, would they become more common/frequent if the body never encountered antibiotic treatment?
If a certain type of bacteria is present in the human body, and they have a mutation allowing for antibiotic resistance, would they become more common/frequent if the body never encountered antibiotic treatment?
A herd of deer is being chased by a pack of wolves. The average running speed of the herd of deer is 30 mph. Only the slowest of the deer are captured/killed. If the slowest 10% are removed, what happens to the new average speed of the herd?
A herd of deer is being chased by a pack of wolves. The average running speed of the herd of deer is 30 mph. Only the slowest of the deer are captured/killed. If the slowest 10% are removed, what happens to the new average speed of the herd?
What does the concept of "selective pressure" by antibiotics mean for bacterial populations?
What does the concept of "selective pressure" by antibiotics mean for bacterial populations?
What conditions are necessary for natural selection to occur in a population of bacteria exposed to antibiotics?
What conditions are necessary for natural selection to occur in a population of bacteria exposed to antibiotics?
A population of bacteria is treated with an antibiotic. Some bacteria survive, reproduce, and pass on their resistance to their offspring. Which evolutionary mechanism is at play here?
A population of bacteria is treated with an antibiotic. Some bacteria survive, reproduce, and pass on their resistance to their offspring. Which evolutionary mechanism is at play here?
Imagine that bacteria A has a mutation that makes it very successful at colonizing the lungs of patients with cystic fibrosis. Bacteria B does not have this mutation. Which of those statements are most accurate?
Imagine that bacteria A has a mutation that makes it very successful at colonizing the lungs of patients with cystic fibrosis. Bacteria B does not have this mutation. Which of those statements are most accurate?
Flashcards
What are antibiotics?
What are antibiotics?
Substances that inhibit bacterial growth or kill bacteria by targeting bacterial cell components not found in animal cells.
What are bacteria?
What are bacteria?
Simple, unicellular organisms that reproduce through binary fission, doubling in number every 4-20 minutes.
What is evolution?
What is evolution?
The change in the frequency of heritable traits in a population over generations.
What is a mutation?
What is a mutation?
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What is Natural Selection?
What is Natural Selection?
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Selective Pressures
Selective Pressures
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The bacteria strike back!
The bacteria strike back!
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Antibiotics treat what infections?
Antibiotics treat what infections?
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Study Notes
Exam 2 and Upcoming Exams
- Exam 2 average was an 84%.
- Three students achieved perfect scores on the exam.
- Make an appointment to review the exam with Jana.
- The lowest of four exam grades will be dropped.
- Exam 3 is scheduled for April 24th.
- Optional, extra-credit final reviews are scheduled during the April 29th and May 1st lectures with 5 extra credit points per lecture that will be added to your lecture participation grade.
- The final exam is on May 8th at 7:30 a.m.
Module 7: Learning Objectives
- Learning Objectives:
- Explain how natural selection and random mutation contribute to the evolution of well-adapted organisms.
- Describe how mutation, gene flow, genetic drift, and non-random mating affect population evolution.
- Define MRSA and describe the ways antibiotic-resistant bacteria strains can evolve from non-resistant strains.
What Are Antibiotics?
- Antibiotics either inhibit the growth and reproduction of bacteria or kill them outright.
- Most antibiotics function by disabling bacterial cell components absent in animal cells.
Bacteria
- Bacteria are unicellular organisms.
- Bacteria are prokaryotic cells with no nucleus.
- They reproduce through binary fission.
- Bacteria are the fastest reproducing organisms, doubling every 4-20 minutes.
How Antibiotics Work
- Tetracycline interferes with bacterial ribosomes, the cellular structures that make proteins; human ribosomes are different enough to be unaffected.
- Penicillin disrupts the formation of bacterial cell walls, preventing cells from forming.
- Ciprofloxacin disrupts an enzyme that helps organize bacterial DNA; this enzyme is different in humans.
- Sulfa drugs inhibit bacterial growth by blocking an enzyme used to produce folate, something humans can obtain from their diet.
Antibiotic Use
- Antibiotics have been used for millennia.
- Evidence suggests molded bread was used in ancient Egypt to treat or prevent wounds.
- Alexander Fleming discovered the antibiotic properties of the mold Penicillium in 1928.
- Fleming left an uncovered petri dish in front of an open window which became contaminated with Penicillium mold, killing nearby Staphylococcus bacteria.
Antibiotic Age
- Fleming’s observation marked the start of the golden age of antibiotic discovery.
- New antibiotics were quickly discovered from natural sources, mainly in the 1950s.
- Antibiotics are thought to have extended the average human lifespan by 23 years.
- Antibiotics were arguably the greatest medical advancement in the 20th century.
Antibiotic Resistance
- Doctors and scientists quickly began to observe bacteria becoming resistant after antibiotics were introduced.
- The first human was treated with penicillin in 1941.
- Staph aureus resistance to penicillin was first observed in 1942.
- By the 1960s, 80% of Staph aureus strains were penicillin-resistant.
- Methicillin, a new synthetic version of penicillin, was introduced.
- Methicillin-resistant Staph aureus (MRSA) strains were observed.
- Healthcare professionals then began to use Vancomycin, a new antibiotic, for highly resistant bacterial infections, only as a last resort.
- Vancomycin-resistant Staph aureus (VRSA) strains were observed in the 1980s.
- MRSA, VRSA, and other “superbugs” were becoming more often found in the clinic by the 2000s.
- Antibiotic-resistant bacterial infections caused 1.27 million deaths worldwide in 2019.
- 35,000 deaths in the US each year are caused by antibiotic-resistant bacterial infections.
- The number of deaths is expected to rise as the supply of "last resort" antibiotics runs out.
- Last resort antibiotics, like vancomycin, have a lot of side effects.
How Bacteria Become Resistant to Antibiotics
- Bacteria become resistant to antibiotics through evolution.
- Evolution is a change in the frequency of heritable traits in a population over generations.
- New traits are introduced to a population through random mutations.
- Not all new traits spread throughout the population over generations, resulting in evolution.
- How the frequency of traits changes
- Evolution needs trait variation in a population and the traits need to be heritable.
- Sometimes individuals with certain traits are more likely to survive and reproduce.
- Natural selection is one mechanism of evolution.
- Evolution is a change in the frequency of traits in a population.
- Natural selection is when organisms with certain traits are more likely to survive and reproduce than other organisms.
- Traits are introduced by random mutations.
- Selective pressures in the environment determine which traits confer a survival advantage.
- Natural selection is driven by environmental factors
- Food
- Water
- Shelter/territory
- Sex
- Evolution can occur quickly, especially in a species with a short generation time.
- Bacterial populations can double in size every 4-20 minutes.
- Selective pressure of antibiotics results in resistance.
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