Welcome to Week 32!  For this week, we will be extending our study of evolution to include the process of constructing phylogenetic trees from physical observations of species, as well as DNA analysis.  Please work through the list of links below.  Each section contains important information and ends with a portion of the weekly assignment.  You can complete it all in one sitting or break it up as needed.  Ready, set, go!

1. Weekly Attendance Check-In (required)
2. How Evolution Works (required)
3. The Beak of the Finch (required)
4. Creating Phylogenetic Trees from DNA Sequences (required)
5. Biology Refresher…review now before it’s too late!
6. Biology Honors Credit…push yourself!

You did it!  Just to make sure, here’s a checklist of items you must complete this week by Sunday, May 3 at 11:59pm:

• Weekly Attendance Check-In (school district requirement)
• Natural Selection Video Recap section of Google Doc (worth 10 assignment points)
• Beak of the Finch section of Google Doc (worth 20 assignment points)
• Sorting Finch Species section of Google Doc (worth 20 assignment points)
• Creating Phylogenetic Trees from DNA section of Google Doc (worth 40 assignment points)

Remember, you can email me any time.  Office hours for Science are Tuesdays from 11am-12pm and Thursdays from 1pm-2pm.  Check your student Gmail for Zoom instructions.

Finally, by popular demand…click here for the Week 32 Bonus Credit Opportunity!

For our final piece of work for this week’s lesson, you will engage in the process of constructing a phylogenetic tree using DNA sequences.  Darwin constructed a phylogenetic tree of the various finch species he encountered in the Galapagos Islands by comparing various physical traits shared by the different species, scientists today construct phylogenetic trees by comparing DNA sequences.  The more similar the DNA sequences, the closer together two species would be on a phlyogenetic tree.  With the move to using DNA sequence-based phylogenetic trees, scientists have a new tool to understand evolution and this has resulted in a number of changes to the what we previously though in terms of the evolutionary relationships between species.

1. Visit the HHMI Creating Phylogenetic Trees from DNA Sequences (available in both English and Spanish)
2. Work through the Click and Learn activity (available in both English and Spanish), adding a new section to your Week 32 Google Doc (section title: Creating Phylogenetic Trees from DNA Sequences).
3. Bonus Activity (not required, but awesome): Watch the video below and see if you can construct a phylogenetic tree using real DNA sequences!

Return to the Week 32 – Phylogenetic Trees post and continue our work for the week.

We often think of evolution as a process requiring many thousands, even millions, of years.  First, random DNA mutations must happen in a gamete which is passed along to an offspring.  If the DNA mutation affects the coding region of a gene, and the gene product (the protein) is altered, more often then not, the mutation has a negative effect on the viability of the offspring.  However, occasionally a mutation will be beneficial, providing the offspring with an increased chance of surviving and having offspring of their own (passing along the new mutation).  Again, mutations occur randomly and it takes time for mutations to spread through a population, something that only happens if the mutation is either beneficial, or at least is not harmful.

Sometimes evolution appears to happen quickly.  This occurs when a genetically diverse population (one with several different alleles, or versions, of a given gene) undergoes selective environmental pressure.  For example, imagine a new virus appears on the scene.  The virus enters cells by binding to a specific cell surface receptor and then injecting its nucleic acid into the cell which can then be copied by the cell to make more virus.  The human population has multiple different alleles of the cell surface receptor.  This is important: each individual person in the population has cells with one version of the receptor (one allele), while there are several alleles of the receptor within the entire human population.  The alleles for the receptor were present before the virus.  Individuals with properly functioning receptors went about their daily life, growing up, having kids, working, working, working, and taking the occasional vacation.

Suddenly, with the arrival of the new virus, the environment changed.  The virus represents a selective pressure.  Because the virus binds to a particular cell surface receptor allele expressed by some (not all!) humans in the population, those humans are vulnerable to infection by the virus.  Sadly, infection by the virus results in the death of anyone infected.  Imagine what will happen to the human population.  If there were five different cell surface receptor alleles before the virus, how many alleles would remain in the population after the virus?  With only four remaining alleles, the population has evolved.  But remember…so has the virus.  Viruses accumulate mutations as well, often at a very fast rate, and given enough time, a mutated virus may be able to bind to one of the remaining four cell surface receptor alleles.  Hopefully scientists will develop a vaccine before that happens!  Note: this is a hypothetical example virus – not the current coronavirus!

Well that was intense!  Let’s lighten the mood with another example of evolution in action: antibiotic resistance.  After watching the Amoeba Sisters video below, complete the Natural Selection Video Recap assignment.  To complete the assignment:

1. Create a Google Doc titled “Week 32 – Your Name” (example: Week 32 – Pickles Swart).
2. Share the document with david.swart@g.highlineschools.org.
3. Create a section in the document titled “Natural Selection Video Recap”
4. Answer questions 1-9 from the worksheet in your doc.

Return to the Week 32 – Phylogenetic Trees post and continue our work for the week.

For the final part of our weekly lesson, sit back and enjoy Jack Horner’s entertaining TED Talk in which he describes his research connecting dinosaurs and chickens.  Listen for the terms embryology, the fossil record, atavisms, and behavior.  Write down a definition of these terms in your Week 31 Google Doc.  Include an example of each term from Dr. Horner’s talk.

Return to the Week 31 – Biological Classification post and double-check that you have completed all of the required work for the week.

Next, watch the Crash Course video below to learn about the concept of taxonomy:

Then download and complete the Biological Classification POGIL (PDF) and email Mr. Swart with any questions and/or attend office hours.  Options for showing your work include:

• Print your own copy, fill it out, and then email Mr. Swart with pictures of your completed work, or
• Write answers to the POGIL questions in your Week 31 Google Doc into a new section titled “Biological Classification POGIL Answers”, or
• Save a copy of the POGIL as a PDF and upload it to your Google Drive account.  From there, open it and click the “add a comment” button in the upper right part of the screen (looks like a comment box with a + sign inside).  Then highlight the question you are answering and then answer the question in the comment box.

Return to the Week 31 – Biological Classification post and continue our work for the week.

We continue our investigation into the history of biological research by moving past Charles Darwin and learning about the work of Carl Linnaeus, the “father” of modern taxonomy.  To begin this week’s assignment, follow the steps:

1. Create a Google Doc titled “Week 31 – Your Name” (example: Week 31 – Carter Swart).
2. Create a section titled History of Taxonomy
3. To place the concept of taxonomy into historical perspective:
   • Click the links below
   • Read about the subject
   • Briefly summarize the historical importance of each of the 5 people into your Google Doc.  (For reference, a link to a previous lesson about Watson & Crick’s discovery of the structure of DNA is also included, as are links to the texts by Darwin and Linnaeus.  These do not need to be read or summarized but are good review materials).

• Biological Classification / Taxonomy (Systema Naturae, published 1735)
  • Carl Linnaeus (1707-1778)
• Theory of Evolution, On the Origin of Species (published 1859)
  • Charles Darwin (1809-1882)
• Structure of DNA discovered in 1953
  • James Watson (1928- )
  • Francis Crick (1916-2004)
  • Rosalind Franklin (1920-1958)

Return to the Week 31 – Biological Classification post and continue our work for the week.

Welcome to Week 31!  For this week, we will be focusing our learning on how scientists have tried to make sense of the world by organizing organisms into groups based on similarities they share.  Please work through the list of links below.  Each section contains important information and ends with a portion of the weekly assignment.  You can complete it all in one sitting or break it up as needed.  Ready, set, go!

1. Timeline of Biological Classification (required)
2. Biological Classification POGIL (required)
3. Building a Dinosaur from a Chicken (required)
4. Biology Refresher…review now before it’s too late!
5. Biology Honors Credit…push yourself!

You did it!  Just to make sure, here’s a checklist of items you must complete this week by Sunday, April 26 at 11:59pm:

• Timeline of Biological Classification section of Google Doc (worth 10 assignment points)
• Biological Classification POGIL (worth 60 assignment points)
• Building a Dinosaur from a Chicken section of Google Doc (worth 10 assignment points)

Remember, you can email me any time.  Office hours for Science are Tuesdays from 11am-12pm and Thursdays from 1pm-2pm.  Check your student Gmail for Zoom instructions.

Finally, by popular demand…click here for the Week 31 Bonus Credit Opportunity!

During the three-week long shut-down, biology students who wish to earn Honors credit had the opportunity to continue their learning with assignments that are now required learning.  Several of you shared Google Docs with me which documented your efforts to work through some of the material.  I sincerely applaud your efforts!  Keep up the good work!

Now that we are back “in school” via distance learning and have the go-ahead to begin teaching new material, many of the assignments originally labeled as Honors credit work will now be required new learning for everyone.

The criteria for earning Honors this semester has been simplified for this class: Students who earn an A for the semester in Mr. Swart’s Biology class will receive Honors credit. This is not a simple task, especially given the challenge of distance learning.  However, I invite you all to give it your best effort and make it your goal to earn Honors credit!