Dtse2007:Central dogma

=Demographics=

=Objectives=

1. Describe the structure and function of DNA/RNA


 * describe what the information specifies and where information in the cell is stored
 * explain the history Watson and Crick derived the DNA model
 * describe the location of genes
 * be able to compare and contrast DNA and RNA

2. Describe DNA replication


 * explain unzipping, binding of primers, DNA polymerase, elongation

3. Describe translation


 * describe how a polypeptide is assembled
 * explain how the order of nucleotides in DNA codes for different amino acids and how this code is transcribed into RNA

4. Describe transcription


 * describe the three different types of RNA and state function of each
 * describe the spatial locations of the different RNAs during transcription and translation

=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?

-OR-

'''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?

=Summary=

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.

=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