Dtse2007:Central dogma

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Interviewee Sex Age Education Background
S1 Female 23 College sophomore High school biology
S2 Female 21 College senior AP Biology
S3 Female 21 College senior High school biology
S4 Male 16 High school sophomore Sophomore biology
S5 Male 16 High school sophomore Sophomore biology
S6 Female 24 College graduate High school biology
S7 Female 21 College senior High school biology
S8 Female 21 College senior High school biology
S9 Male 23 Super Senior High school biology
S10 Female 21 College junior High school biology
S11 Female 19 College sophomore AP biology
S12 Male 25 College graduate High school biology


'Explain the connection between genes, proteins, and traits'

  • Describe the structure and function of DNA- DNA as the genetic material
    • describe where information in the cell is stored (chromosomes are made of DNA and they carry our genetic information
    • semi- conservative DNA replication
      • explain unzipping, binding of primers, DNA polymerase, elongation not an enduring idea
    • describe the location of genes

  • Decoding DNA codes for proteins
    • Describe transcription- RNA is a copy of DNA made in order to prevent risk of damage to DNA
    • structure and function of RNA
      • describe the three different types of RNA and state function of each
    • describe the spatial locations of the different RNAs during transcription and translation
    • be able to compare and contrast DNA and RNA
    • Describe translation DNA nucleotides code for amino acids
    • explain how the order of nucleotides in DNA codes for different amino acids and how this code is transcribed into RNA
    • shape of proteins in relation to function
      • describe how a polypeptide is assembled

  • From genotype to phenotype- proteins are the intermediate between genes and traits**Explain the connection between genes, proteins and traits no sub ideas here? This is a very big idea I would give it more attention

Interview Protocol

What causes people to have different colored eyes? (Genes)

  • What are your parents giving you?

(if grounding out, introduce the term gene, DNA or blue print)

Where are genes?

  • How does a gene cause the eye color?

Can you draw me a picture of where a gene is located?

  • Describe the picture to me

What is DNA?

  • Where do you find DNA?
  • What does DNA look like? (maybe a picture)
  • Can you draw me a picture of where DNA is located and what it looks like?
  • Describe the picture to me

Is there a connection between genes and DNA?

  • What is the connection?

College Student Say both parents work out a lot and are very muscular, will their children be very muscular too?


Middle/ High School If a mother and father were in a car accident and lost both of their arms, how would their children be born? (looking for them to say whether it is genetic or environmental)

How do genes cause genetic disease? (do they give you a different answer than eye color)

What are proteins?

  • How does that connect to the proteins your bodies make (if they take a food approach)?

Is there a relationship between DNA and proteins?

  • What is the relationship?


The big ideas that our interviews focused on were:

1. The location of genetic information 2. How genetic information becomes expressed in proteins 3. The basic structure of nucleic acid and protein 4. The connections between: genes and DNA, proteins and DNA, proteins and traits 5. What causes genetic disorders. 6. Genetic inheritance (specifically DNA)

The trends we encountered in students’ thinking about these ideas:

1. When we probed to see what our interviewees knew about the location of genetic information, we got a variety of answers. They believed that DNA is located in the cells, blood, on a gene, or in the nucleus of a cell. When it came to the location of genes, some thought that genes are everywhere, or “on earth”, while others thought genes were located on DNA or in cells.

2. The next big idea we interviewed about was how genetic information becomes expressed in proteins. Many of the students had no idea, while others had reciprocal answers saying, “It’s expressed by your genes and then your genes express it”, proteins are what DNA is made up of, proteins are encoded from DNA, and proteins make the trait. Most students seemed to not even be able to distinguish what a protein’s composition was. Common answers when we asked about what a protein was were: protein is in DNA, proteins make DNA, or proteins are manufactured by ribosomes.

3. We also explored their knowledge about the basic structure of nucleic acid and proteins. When discussing nucleic acid, many of our interviewees had a good idea of its structure and mentioned a double helix structure, back bone, base pairs, and cork-screw twist with inter-locking pairs, while others mentioned the structure is a circle, with little circles in it. This could be the result of graphics and pictures in most biology text books which help give students a basic idea of DNA structure. As for the structure of a protein, the answers we received were, no idea, a string of amino acids, the need for synthesis, the building blocks of life, and that proteins are substances made up of hydrogen, nitrogen, and carbon.

4. After interviewing them about the ideas above, we questioned them to see if they thought there were connections between: genes and DNA. As for genes and DNA, some thought there was no connection, others said there was a connection and it was that genes are on DNA, while others thought that different combinations of DNA make up genes. We also got answers such as, “DNA makes up your genetic sequence which is like your genes”, genes are made up of DNA, DNA is the building blocks of life while genes are the building blocks of people, DNA carries genes, our genes are determined by our DNA and if you put DNA together that would make up a gene.

5. When asked what they thought causes genetic disorders, many mentioned mutation, unusual cells or unusual forming of cells, messed up chromosomes, that something goes wrong with the chromosomes such as they mix up, that there is a mess up in the code on DNA, or that the codon gets messed up which causes proteins to be misshaped.

6. Finally, when it came to the question of genetic inheritance almost all interviewees had an idea that you received something from your parents. Many students mentioned that you got genes or chromosomes from your parents, but often kept using both terms interchangeably. We also received answers such as, it’s recessive from your parents, you receive an x and y, and punnett square. In several interviews the word chromosome wasn’t even mentioned and students failed to realize a gene is a segment of chromosome carrying genetic information.

Common trends that we experienced were that often people would use terms that they did not know the correct meaning of and they would often repeat the same idea for more than one concept. There were some students that mentioned that they knew about the little details but became confused about the overall picture. We also saw that many students knew surface ideas about many of the concepts, but did not fully understand them.

What instructions will need to achieve (Driver’s analysis)

After reviewing the common trends we observed in the interviewees prior knowledge, we discussed what instructions will need to achieve in terms of Driver’s analysis. In Driver’s article she wrote of using instruction to develop existing ideas, differentiate between ideas, integrate ideas, change existing ideas, and to introduce new ideas.

In terms of the location of genetic information, instruction needs to develop existing ideas. We can branch out a bit from what students already understand such as DNA storing genetic information, and build on this pre-existing knowledge by incorporating models and pictures of genes and chromosomes.

As for how genetic information becomes expressed new ideas need to be introduced to students, while instruction needs to differentiate genes from DNA, genes from alleles, and genes from chromosomes. Visual models and hands on activities may aid in students mental idea of these different parts to help them differentiate the material they are encountering.

When devising lessons for the structure of nucleic acid and proteins (structure and function), instructions need to introduce new ideas and develop exiting ideas. It seems since knowledge of proteins was so lacking that this is an area that needs to be focused on and built on a lot.

When it comes to the connections between the concepts such as connections between DNA and genes, instructions need to first differentiate existing ideas about genes and DNA and then integrate concepts related to both into a conceptual framework.

For genetic disorders, instruction needs to integrate existing ideas, such as combining students’ ideas about DNA and genes with genetic disorders. Instruction also needs to focus on differentiating students ideas on what can and cannot be passed down due to genetic or physiological factors.

Project Context

  • Students will be given a news article explaining a phenomenon observed among the Philippine prostitute community regarding their ability to contract HIV/ AIDS. The idea is that these prostitutes were found to have a mutation in a T-cell receptor gene (CCR5) that prevented the translocation of the virus into the cells. Because this is a genetic ‘defect’ in an extra cellular protein, in order to gain a full understanding of this process the students must gain an understanding of genes, their location, the structure and function of DNA and the process by which genes are decoded and expressed as a phenotype. Basically how genetics traits results in physical phenotype such as non-susceptibility to disease. Not that this doesn’t really motivate the need to understand DNA replication, you could just understand decoding and solve the problem.

Project Backbone

  • Driving Macrostructure 1: Explain why some people do not become infected with HIV even though they are exposed (this is an EC/R macrostructure)
    • Nested Structure 1.1: Introduction
      • Lesson 1.1-1: Introduction
        • newspaper article
        • fact sheet on HIV (including brief discussion on the virus)
        • class generates plausible reasons
          • if they don’t introduce genetics as a plausible reason, prompt them to it
        • Break up students into research groups and describe the overall structure we will be following to uncover the reason. Tell the students that we will be working in research groups and looking at studies and data that will help us find out what is going on in these Philippine people.
        • At the end of the period and to finish for homework, groups or individuals should brainstorm ideas about possible ways to test the models discussed in class.
        • Give out studies for Lesson 2.1 for overnight reading.
    • Nested Structure 1.2: Genes part 1
      • Lesson 1.2-1: Is the trait genetic or one of the other models? Provide students with a study that presents data about genes in susceptible individuals and those not. The logistics of the data and how it came about is inconsequential but the fact that they will be able to compare individuals’ genes is all that we need.
        • As students read the study they will uncover data that links the instances of the prostitutes discussed in the introduction to a specific gene that these prostitutes do not have but others do have. So what is it about this gene that allows people with it to contract HIV and those without it to be immune? From this point forward this gene will be known as the “HIV gene.”

  • Driving Macrostructure 2: Can we use this “HIV gene” to prevent others from contracting HIV or treat people with HIV? (CD/A)
    • Nested Structure 2.1: Genes part 2
      • Lesson 2.1-1 Continued from Lesson 1.2-1: What are genes? Because students will likely not have a specific understanding of genes, a brief lesson on genes will be provided when students complete the study activity from part 1 of the lesson.
      • The gene lesson will include only enough information to move on to the next stage of the investigation. Information will include:
        • The premise behind inheritance (brief reminder of Mendelian Genetics they ‘learned’ in middle school- no punnett squares yet.)
        • But what are genes? How does this magical thing called a gene end up preventing HIV infection? How do they work in the cell/our body?
        • Talk about some of the original macromolecules scientists believed could be the basic unit of inheritance in very little detail (perhaps a short powerpoint with pictures of them). These models included Lipids, Proteins, Carbohydrates, and Ribonucleic Acids. Explain some of the difficulties we had at the time in understanding, which was the unit of inheritance to give a historical problem context.

Students will read, for homework, the historical studies to find out which of these macromolecules is the unit of inheritance. (Avery and Griffith)

      • Lesson 2.1-1 (Day2): What are genes made of? Do Now: to start off the period that brings students back to the task (perhaps which macromolecule do you think is the unit of inheritance after reading the studies for homework?). In groups students will discuss the studies that they read for homework and create models. These studies should include those by:
        • Frederick Griffith - Study
        • Oswald Avery - Study

After this lesson, students will understand the connection of DNA to Genes. Thus it follows that DNA is the basic unit of inheritance. The next step toward finding out if we could use the “HIV gene” for medicinal purposes is to find out more about DNA.

Students will read, for homework, the following studies considering the next step toward finding out if we could use the “HIV gene” for medicinal purposes- to find out more about DNA:

  • Erwin Chargaff – Study
  • Franklin and Wilkins
  • Exert from James Watson’s The Double Helix
  • Original Replications models and Studies revealing semiconservative replication

These studies are very short and to the point …see Studies

  • Nested Structure 2.2: DNA Structure and its Function
    • Lesson 3.1: What is DNA? How do organisms use it to pass on genes? Can we capitalize on this process to use the “HIV gene” on the DNA molecule for medicinal purposes? Do Now: Based on readings from the night before have students draw what they think DNA looks like and tell what sets it apart from the other macromolecules we first thought could be the unit of inheritance.

When finished discussing these studies with their research groups, students will have an initial background on the structure and function of DNA. They will have learned some of the history of DNA research and the key factors that led to our modern-day understanding of Genetics.

      • Following the discussion of some of the original studies, students will be presented with a lesson that further clarifies the information they have extracted from the studies detailing structure and method of replication of DNA. This lesson will include information on:
        • Double Helix
        • Phosphate group, Sugar group, Base groups (A, T G, C)
        • Polymer qualities. Ways all units are linked. Review of Chemical bonds unit
        • How DNA replicates:
          • Helicase
          • Primers
          • Polymerase

At the completion of this lesson, students will have a more concrete understanding of the information presented in the studies. By continuously referencing the studies in the lesson we reinforce the history as well.

Useful Technologies

Some useful technologies that could be applied to this unit are:

Powerpoint-to present the material Powerpoint homepage

Virtual Labs-for hands-on experience Virtual Lab

Wikipedia-for research Wikipedia

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