1 / 35

Lab: Assessing Population Dynamics of Saccharomyces cerevisiae

Lab: Assessing Population Dynamics of Saccharomyces cerevisiae. Purpose: To assess the relationship between concentration of limiting factors on the carrying capacity of microorganism populations. Methodology: Spectrophotometry

kevina
Download Presentation

Lab: Assessing Population Dynamics of Saccharomyces cerevisiae

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Lab: Assessing Population Dynamics of Saccharomyces cerevisiae • Purpose: To assess the relationship between concentration of limiting factors on the carrying capacity of microorganism populations. • Methodology: Spectrophotometry • Hypothesis: How will the percentage of fructose impact the changes in the size of the Saccharomyces cerevisiaepopulation? Which populations do you expect to grow and stabilize? Which populations will fail to thrive?

  2. Saccharomyces cerevisiae • “Brewer’s Yeast” • Kingdom Fungi • Utilize fructose and other simple sugars as the basis of their metabolism • Reproduce via binary fission (asexual reproduction)

  3. Spectrophotometry • Indirectly measures population size of microorganism culture • The greater the percent transmittance, the smaller the population

  4. Protocol: Calibrating the Spectrophotometer • 1) DO NOT CLEAN OUT THE STANDARD REFERENCE VIAL • 2) Insert the standard reference into the chamber of the spectrophotometer, matching the arrow on the vial with the arrow on the spectrophotometer • 2) Using the stylus, select “calibration” f.rom the “sensors” menu • 3) Click “calibrate now” on the upper left side of the screen • 4) Enter 100 into the box for “Reading 1 Known Value” and “Keep” this value. Repeat for Reading 2 Known Value. When finished, select “OK” from the lower right corner.

  5. Protocol: Preparing the Dilutions • 1) Clean and dry the testing vial • 2) Suspend each of the five cultures of Saccharomyces cerevisiaewith the stirring rod. Qualitatively assess for smell and color. • 3) Using a graduated dropper, transfer 2mL of culture to a clean test tube • 4) Dilute the culture sample with 18mL of tap water (this should fill the test tube to the line) • 5) Insert the vial into the spectrophotomer • 6) Determine % transmittance (in NTU) with the spectrophotometer • 7) Repeat steps 1-6 for all percentages

  6. Actions prove who someone is. Words prove who someone wants to be. On the same token, an honest enemy is much better than a fake friend.

  7. Nemesis v. Archenemy

  8. Predation can be a positive influence in keeping invasive populations in check around the carrying capacity (K)

  9. Populations without predators often drastically exceed the carrying capacity, crash and fail to recover

  10. Lotka-Volterra Equation • Ecological equation describing the relationship between predator and prey • In populations when predator populations grow too rapidly, the amount of prey can fluctuate dangerously, putting the entire ecosystem at risk

  11. “Super-Predators”? • Human population growth is causing rapid declines in the number of prey (i.e. hunted species) in their habitats • As a result, populations of prey are forced to reproduce at an earlier age. Fecundity can’t change because resources don’t increase. • This shift in age structure also makes populations vulnerable.

  12. HOW DOES THIS APPLY TO HUMAN POPULATIONS?

  13. HUMAN POPULATION GROWTH

  14. Population Growth?

  15. How big will it get? • There are three major prediction models for the future (2050) • 7.3 billion • 9 billion • 10.7 billion • Most predictions depend on the decline in fecundity

  16. What is the ecological cost of unchecked human population growth?

  17. Megacities & Suburban Sprawl

  18. Why is pattern of population growth so different?

  19. PROCEDURE • Assume Biotic Potential: All offspring survive, are capable of reproducing and do reproduce at maximum fecundity. All members survive until end of simulation • At each generational division, multiply the previous population size by the fecundity • Continue on until you reach or just exceed 100 years (to nearest gen. Interval)

  20. ASANO FAMILY (Japan) • Generational Time: 22yrs • Fecundity 1.5

  21. Bwana Family (Senegal) • Generational Time: 15 Years • Fecundity: 7.4

  22. Khan Family (Turkey) • Generational Time: 18 Yrs • Fecundity: 6.2

  23. Olsen Family (Sweden) • Generational Time: 27 yrs • Fecundity 1.5

  24. Ortiz Family (Mexico) • Generational Time: 18 yrs • Fecundity 5.3

  25. Smith Family (USA) • Generational Time: 25 years • Fecundity 2.2

  26. What is the most important factor in determining population size (fecundity, nationality, age of 1st birth, name)?Explain

  27. The future (even with one-child policies)

  28. Zero Population Growth is a goal of many nations China and other nations are pushing for replacement rate reproduction What about ZPG?

More Related