Category Archives: Central Dogma

Chromosome Project Poster Walk

The chromosome project culminated today with a poster walk.  Students placed their posters on their desks and then looked over each other’s posters while completing the poster walk handout.  After the poster walk, students turned in the handout (15 points), their completed posters (10 points), and their research notes (25 points).

Selected Chromosome Project Posters

Strawberry DNA Lab Report

As we enter our final week of Unit 4, students received a progress report, their graded quiz from Friday, and a copy of the Strawberry DNA Extraction Lab Checklist.

Students with a D or F we told that in order to qualify for an in-progress (IP) grade at the end of the semester, they need to take their progress report home, explain it to their parent/guardian, craft a plan to pass biology, and then bring the progress report back signed and with a written plan.

We briefly reviewed the quiz and most students achieved a perfect score, solving the RNA and amino acid sequences perfectly.  Because there were two versions of the exam, with table partners receiving different copies, it was immediately evident if any copying occurred.  Students were again reminded about the importance of academic honesty, and students who copied received a score of zero.

Next, we reviewed the lab checklist and then watched the video below to provide students with the academic learning required to explain the role of soap, salt, and isopropyl alcohol in the lab.

Finally, students who completed the New Genetics assignment were allowed to use class computers to begin writing their lab reports.  Students who have not yet completed the assignment had class time to do that work.  Students were reminded that the lab report is due Thursday and we have an exam Friday.

Strawberry DNA Extraction Lab

Class sets of extracted DNA grouped by the type of soap used in the extraction solution:

Period 1 DNA Results
Period 4 DNA Results
Period 6 DNA Results

Student-acquired pictures of DNA samples under the microscope:

Labels for the different soaps used in the extraction solutions:

Shampoo Back
Dawn Dish Soap
Dawn Dish Soap Back
Green Apple Dish Soap
Green Apple Dish Soap Back
Hand Soap
Hand Soap Back

EOC Review: Evolution Review – Your Inner Monkey

We concluded our Biology End of Course review by watching the PBS video Your Inner Monkey.  The video does a nice job of bringing together the key concepts from our units on evolution and central dogma.  Tomorrow, students will sit for the EOC.

All three episodes of the movie series are listed below:

  1. Your Inner Fish
  2. Your Inner Reptile
  3. Your Inner Monkey


Central Dogma: Chromosome Project

Update: March 2

Today marks the final day of class time for working on this portion of the Chromosome Project.  After our entry task, students who have completed the project will be offered the opportunity to present their work to the class for feedback.  For those who finish early, please complete The New Genetics reading assignment (Chapter 1) from February 9.  When that assignment is complete, the next reading assignment is Chapter 4 from Inside the Cell (define vocabulary words in bold and answer the questions at the end of the chapter).  Notes from the entry task are shown below:

Update: March 1

A complete presentation will have the following sections:

  1. Information connecting Chromosome, DNA, Gene, Protein, and Trait (Disease/Condition)
  2. Information about Disease/Condition
  3. Researcher = Your Name
  4. Research connection between Gene and Disease/Condition
  5. How is the disease/condition inherited? Are the genetics known?
  6. Update references in APA format

Use the Citation Machine website to help you cite your sources using APA format.  Sources need to be referenced on the last slide of the Google Slides document you are working on.

Original Post: February 25

Welcome to the Chromosome Project!  Yesterday you had the opportunity to research one or more genes known to be involved in a genetic disease or condition of interest to you.  You then located the gene on a particular chromosome.

Now your work begins!  Your mission today is to learn as much as you can about the gene you identified yesterday.  Record your findings in the Daily Log located in Google Classroom.

To research your gene, visit the NCBI Human Genome Resources page and enter your gene name into the “Find a Gene” box on the left panel.  Be sure to select “homo sapiens” in the pull-down box.  When the search completes, click on your gene name (typically the first gene on the list) and browse through the entry.  There is a ton of information provided!  The length of the gene can be found by hovering your mouse over the top green line under the “genomic regions, transcripts, and products” and looking for the number after the word “length.”  The length of the amino acid sequence can be found by clicking on the word “protein” on the right hand side of the page under Related Information.  Browse the entries for the full-length protein and note the number of amino acids in the protein.  The full-length protein can be challenging to find: look for an entry that does not include words like truncatedisoformpredicted, synthetic construct, or unnamed protein product.

Another great website to visit to learn more about specific genes is  Just type your gene name into the “Explore a Gene” search box and appreciate the power of the Internet!  NCBI PubMed contains a huge database of scientific papers – search for your gene and see what articles are out there.

You can use all of this information to edit the Chromosome Project Template Slides also located in Google Classroom.  If time permits, continue researching the disease/condition you selected.  Your goal is to learn what you can about what the disease/condition is and how it is inherited.

Welcome to research!  Use your time well and challenge yourself to learn new things!

Central Dogma: Structure and Function of Genes

With several students missing class today because of testing and a field trip, we practiced converting amino acid sequences to DNA sequences and then reviewed the DNA mutations introduced yesterday.  Students modeled frameshift mutations by inserting or deleting individual DNA bases into their initial DNA sequences and decoding the new amino acid sequences encoded for by the mutated DNA.

Several students observed the introduction of premature stop codons into their amino acid sequences.  We then looked at the structure of chromosomes, zooming in on a segment of chromosome 22 and then focusing further on a single gene.  Students sketched out the gene and then learned the following vocabulary terms:

  • Regulatory DNA sequences: DNA bases that control gene expression.  Not transcribed into mRNA.
  • mRNA: introns and exons transcribed from a DNA segment (a gene)
  • Introns: stretches of DNA transcribed into mRNA that are excised (removed) before the mRNA is translated to protein.  Also called “junk DNA” – but shouldn’t be!
  • Exons: segments of DNA transcribed into mRNA that are stitched together after intron excision for translation into protein

The white board pictures below show how precursor mRNA is processed to remove introns and stitch together exons to form the mature mRNA.

Previously, scientists believed one gene coded for one protein.  As our understanding of introns and exons improved, and as scientists developed improved methods for sequencing mRNA, scientists realized that one gene coding for one precursor mRNA could actually make many different (yet related) proteins.  For example, one mature mRNA might include all of the exons (after all introns are removed), while another mature mRNA might be missing one or more exons.  Called alternative splicing, this process allows a gene to code for more than one protein and helps explain the vast diversity of proteins found in the different cells that make up the human body.  Remember, all cells share the same DNA, but only some of that DNA is expressed by certain cells, and that expressed DNA (mRNA) can be spliced in various ways resulting in many different proteins.

As we transition toward our study of chromosomes, students will research disorders with a known genetic cause (start here).  Students will also have access to a variety of posters showing the molecular basis of health conditions they may also wish to study.  One they have identified a disorder, students will research genes known to associate with the condition.  Finally, they identify the number of the chromosome on which their gene resides.  The chromosome number they identify will be their assigned chromosome for the Chromosome Project.  Students will have a substitute teacher tomorrow who will instruct them to use the Chromebooks to visit the class website for details about the Project and instructions for how to begin.

Central Dogma: Cystic Fibrosis Case Study

In today’s lesson, we used a case study about cystic fibrosis as the mechanism to:

  • review the stop codon;
  • connect the concepts of protein structure and function;
  • review how R groups differentiate amino acids;
  • review how R group interactions result in protein folding;
  • discuss “structure equals function”;
  • bring a human face to a genetic disease;
  • and help students recall the mechanism of genetic inheritance.

For the entry task, students were challenged to consider how genes begin and end.  We discussed how mRNA sequences always begin with AUG (which codes for methionine, and amino acid which may also occur elsewhere in a protein).  Students were then reminded of the three “stop codons” and we reviewed how those work to release a protein from the ribosome.  We reviewed the structure of amino acids, focusing on the 20 different R groups and how those R groups each have different properties.  The interactions between R groups determine protein shape, and shape determines protein function.  When the sequence changes, the shape changes, thus changing the function of a protein.  We then moved into the cystic fibrosis case study, first watching the video below and then working through the lesson PowerPoint.

Pictures from the white board today:

Central Dogma: Nature vs Nurture

As promised yesterday, students received the first 15 minutes of class to complete their quiz from yesterday.  After the quiz, we transitioned to the final segment of Central Dogma: traits.  We reviewed the key vocabulary concepts associated with Central Dogma and introduced the vocabulary word phenotype (the set of an organism’s observable characteristics).  We discussed how we are born with some traits (nature) while others we acquire during our lifetime (nurture).  Students learned about how scientists study the origin of traits through twin studies, and we watched a short video (below) where twin sisters raised in very different environments were studied after being separated for 35 years.  Students then worked in small groups to debate whether a list of traits provided on a worksheet are inherited via nature, nurture, or both.  The activity was so engaging we will allocated additional time tomorrow to complete the work.

Updated 2/19/16: After meeting in groups of 2-3 yesterday, students were challenged to identify other small groups of people they haven’t worked with recently and who might have different ways of thinking about how traits are inherited.  After 15 minutes of respectful scientific debate, students returned to their seats and took the remaining 30 minutes of class to respond to the following writing prompt:

Identify a trait you marked as being inherited through both nature and nurture.  Write a clear explanation supporting your position.  Include evidence! 

If someone were to disagree with you, what might they argue (counter-argument)?  Explain what evidence you have (or what evidence you might need) to defend your claim.

At the end of class, students turned in both the written response as well as the traits worksheet.

Central Dogma: Central Dogma Quiz

As promised last Friday, students were greeted with a quiz to start the short school week.  With the two copy machines unavailable this morning, we were extremely fortunate to have the Chromebook cart available to us today.  Students accessed the quiz on Google Classroom and answered the questions on a separate sheet of paper.  Students will have an additional 15 minutes of class time tomorrow to complete the quiz.