DNA Structure Tutorial

VGEC: Activity Notes

DNA Structure Tutorial

A group-work tutorial in which students examine the structure of DNA using semi-space-filling molecular models. It can be used in conjunction with the GENIE DNA sequencing tutorial.

For more information on this project, visit the project pages on the GENIE website at: http://www.le.ac.uk/genetics/genie/project_dna.html

Intended learning outcomes

·  To be able to recognise the structural elements of DNA at the molecular level: base pairs, sugar-phosphate backbone and double helix.

·  To understand the base-pairing rules, and be able to recognise the purine and pyrimidine bases.

·  To be able to identify the nucleotide sequence of a given DNA section (say, 10 or 20 nucleotides) and replicate the sequence using a mini-model.

Files provided

1 DNAStructure.docx/rtf/pdf This document, which sets out the aims of the activity and the materials required.

2 StudentNotes.docx/rtf/pdf Student Notes, containing instructions for the student.

3 Introduction.pptx/pdf A PowerPoint presentation to introduce the activity, including a slide showing a 300 base pair DNA model [optional].

4 Evaluation charts.xlsx This Excel spreadsheet is used to create evaluation charts.

5 GATcDNA structure.pptx/pdf A PowerPoint presentation which shows the structure of GATcDNA.

Files available on request

DNAStructureAnswerNotes.pdf A document containing answers to the questions in DNAStructureStudentNotes.
Available from GENIE. Use the Comment on the VGEC or Resource Feedback
buttons on the VGEC to request a copy or email .

Procedure

1  Students are provided with a detailed molecular model of a DNA sequence (say, 10 or 20 base pairs long).

2  The Students works through the Student Notes provided (DNAStructureStudentNotes.pdf), using the model to answer questions about the structure of the DNA double helix. The Student Notes provided here are for use with MolymodTM Molecular Models, but could easily be adapted to work with other modelling systems.

3  The topics covered include:

·  The scale of the model, and its relationship to the human genome

·  The number of base pairs per helical turn

·  The location of the major and minor grooves

·  The identification of the purine and pyrimidine bases in terms of their molecular structure (using photographs of appropriate molecular models)

·  The identification of the carbon – phosphate group links between adjacent nucleotides

·  The identification of the nucleotide sequence along both strands in the 5′ to 3′ direction.

4  The students can then use their nucleotide sequences to replicate the sequence in the DNA model using a simpler modelling system (for example, the miniDNATM Molecular Model Kit).

Materials

We used the following modelling systems for this tutorial, but it can be adapted to work with other systems.

·  For the semi-space-filling molecular model we used the MolymodTM Molecular Models from Spiring Enterprises Ltd:
http://www.molymod.com/index.html

·  For the simpler component modelling system, we used Advanced miniDNATM Molecular Model Kit from Spiring Enterprises Ltd:
http://www.molymod.com/index.html

For other DNA modelling systems see the following page from National Centre for Biotechnology Education:

http://www.ncbe.reading.ac.uk/dna50/models.html

Comments

Some students find Questions 1 and 2 in the Student Notes difficult and may need additional support.

Virtual Genetics Education Centre: http://www.le.ac.uk/ge/genie/vgec/ 1