Imaging DNA Structure
Engineering advances have made possible computer-generated images, such as this rendition of a restriction enzyme (in gray) attached to a DNA double helix.Copyright Nature http://www.nature.com/scitable/spotlight/restriction-enzymes-18458113
Students are introduced to the latest imaging methods used to visualize molecular structures and the method of electrophoresis that is used to identify and compare genetic code (DNA). Students should already have basic knowledge of genetics, DNA (DNA structure, nucleotide bases), proteins and enzymes. The lesson begins with a discussion to motivate the need for imaging techniques and DNA analysis, which prepares students to participate in the associated two-part activity: 1) students each choose an imaging method to research (from a provided list of molecular imaging methods), 2) they research basic information about electrophoresis.
Visualization of small structures such as the molecular structures of complex proteins and genetic material (DNA) is based on engineering discoveries and breakthroughs in physics at small scales. Imaging technologies such as x-ray and scanning electron microscopy—used by scientists and engineers to image microscopic structures—are also used by biomedical engineers and biologists to study biomolecules, cells and tissue samples. Microfluidics concepts and devices used to study colloidal particle flow are also employed by biologist to study and filter biomolecules. Gel electrophoresis is one example of the many engineering technologies that biologists use to compare fragments of DNA samples.
After this lesson, students should be able to:
- Enumerate some of the imaging technologies used for atomic scale microscopy.
- List the basic, underlying principles of the researched microscopy method.
- Describe how the microscopy method helped scientists to discover the structure of biomolecules.
- Explain the difference between molecular imaging and DNA gel electrophoresis.
- Explain that certain nucleotide base sequences in the DNA encode for proteins/enzymes, whereas the molecular shape of protein/enzyme determines their functions.