Reading: 1) Chapter 14 in Biology for a Changing World, by Shuster, Vigna, Sinha, and Tontonoz (2012)

Transcription

1 Biology 100 Winter 2013 North Seattle Community College Reading Guide 12 Natural selection and adaptation Reading: 1) Chapter 14 in Biology for a Changing World, by Shuster, Vigna, Sinha, and Tontonoz (2012) Directions: Fill out the reading guide as you read. Again, the reading guide is designed to help you take notes from your reading. Along the way, I will ask you some Critical Thinking questions that are designed to help stimulate your thinking as to how the concepts and vocabulary from the book can be used to help explain our Essential Question. As you read, keep our Essential Question in mind: How is this information helping me to explain how resistance happens? The BIG concepts that you ll be learning in this reading: Reproduction and Heritability Genetic Variation Natural Selection and Adaptation Take a look at the BIG concepts that you ll be learning in this reading just above. You explored these underlined concepts in Lab 7: Modeling Evolution; Heritability, Variation, Selection. What have these concepts got to do with explaining how resistance happens? In class so far we have been generating a model that helps us to explain how HIV drug resistance might come about. Critical Thinking 1: Write down your Time 0, Time 1, Time 2 model of how you think HIV drug resistance happens, just as we did in class. Remember, this is a model, which we will test by getting more evidence from this reading, then reflect and revise our model to add in this new information. Time 0 Time 1 Time 2 (no HIV drug) (not long after taking (7 years after taking HIV drugs) HIV drugs) Explain in words what is happening in your model:

2 Now let s get some more evidence while we learn about a different but similar situation: Antibiotic resistance! Chapter 14 in Biology for a Changing World Staph the Microbe 1. Why can staph bacteria cause such a range of disease? 2. How does a strain differ from all other strains? 3. Why was Ricky Lanetti s treatment too late? The Antibiotic Revolution 4. What are beta-lactams and how do they work? Acquiring Resistance 5. Finish this sentence: Bacteria might never grow resistant to drugs if NOTE: an allele is an alternate form of a gene. Recall this slide from an earlier class below: The hemoglobin gene has two different alleles in this picture. One hemoglobin allele codes for the normal structure of hemoglobin protein (normal trait), while the other hemoglobin allele codes for the sickle-cell structure of hemoglobin protein (sickle-cell trait). One gene (hemoglobin gene) : different alleles (alternate forms of hemoglobin gene). The alleles differ because of DNA mutations in the hemoglobin gene in different people. A mutation is a change in the nucleotide sequence of a gene. If you look at a population of humans, in different people you will find different mutations of the hemoglobin gene (these are the different hemoglobin alleles). This results in genetic diversity (lots of different alleles) in a human population!

3 Critical Thinking 2: Now, applying that new knowledge, DRAW A PICTURE of a population of bacteria that have different alleles of a gene, called gene X. EXPLAIN IN WORDS underneath your picture how gene X can have different alleles that result in a population of bacteria with genetic diversity: 6. Like all organisms, bacteria acquire mutations when 7. Explain how parental DNA is passed on to daughter bacterial cells as they reproduce by the process called binary fission. REDRAW Infographic 14.3 in your explanation.

4 8. Explain how a DNA mutation can happen and is then passed into a daughter cell: 9. Would you characterize the genetic diversity of a bacterial population as HIGH or LOW (circle one)? Critical Thinking 3: Now explain again, in your own words, how genetic diversity of a population of bacteria can come about: 10. What is gene swapping (also known as gene transfer)? 11. Summarize the two different ways that populations of staph bacteria can become resistant to antibiotic drugs (acquire genetic variation: Infographic 14.4): 12. Specifically, the altered or acquired genes code for proteins that

5 13. What is an example of how some bacteria specifically resist beta-lactam antibiotic drugs? Critical Thinking 4: A) In Lab 7, Experiment 1, describe the amount of variation (genetic diversity) you saw in the population of dots and what happened after you went through 5 rounds of clicking on (preying on!) the dots. Was there a change in the overall trait (speed) of the dots by the end of the 5 rounds? B) Compare this to our class results for Experiment 3 when there was no variation in the population of dots. Was there a change in the overall trait (either speed or size) of the dots by the end of the 5 rounds? Explain why. C) Which model, either Experiment 1 (with variation) or Experiment 3 (without variation) more closely explains how drug resistance happens? Explain why. How Populations Evolve (This is called evolution by natural selection!) 14. An entire population of bacteria with a new trait can arise only when 15. What is a population?

6 16. Explain how antibiotic resistance happens (p 278): Critical Thinking 5: Write down your Time 0, Time 1, Time 2 model, just as we did in class, but this time for how you think antibiotic drug resistance happens. Time 0 Time 1 Time 2 (no antibiotic) (not long after taking (a long time after taking an antibiotic) an antibiotic) Explain in words what is happening in your model:

7 17. What is evolution? 18. What is an organism s fitness (Infographic 14.5)? 19. Explain how some antibiotic-resistant bacteria survive well inside of hospitals, but poorly outside of hospitals. Patterns of Natural Selection 20. What is their definition of natural selection (see the side bar on pg 279)? 21. What is an organism s phenotype? Critical Thinking 6: A) In Lab 7, what was the environmental pressure or selection that caused your dots to be removed from the population? B) In our class results for Experiment 3, when selection was deselected, how did the absence of selection affect the ability of the population to change over time compared to Experiment 1? Critical Thinking 7: A) In Lab 7, what happened in the class results for Experiment 3 when heritable was deselected? B) How did the absence of heritability affect the ability of the population to change over time compared to Experiment 1?

8 22. What is adaptation? 23. Does evolution by natural selection occur in POPULATIONS or INDIVIDUALS (Circle one)? Why (Infographic 14.6)? 24. What is directional selection? 25. What is stabilizing selection? 26. What is diversifying selection? Critical Thinking 8: What pattern of natural selection did you observe in Lab 7, Experiment 1? 27. Why is hand washing so important to do, especially by healthcare workers? 28. What is the rate of hand washing among healthcare workers? 29. What can we do to treat and prevent infection by antibiotic-resistant bacteria (Infographic 14.8)? Critical Thinking 9: Has your model explaining how HIV drug resistance happens changed with this new information? If so, how? If not, why not?