Engineering a Tomato

This computer exhibit guides the visitor through the complex steps of transferring a gene from one organism into another. An anti-freeze gene from a fish is moved into a tomato and, as a result, the tomato is protected against freezing conditions. By experimenting to keep tomatoes from freezing the visitor learns how genetic engineering can aid agriculture by making plants more resistant to harsh conditions.

DNA Determines Traits in Living Things

At this exhibit, visitors observe how minor changes in DNA can alter the appearance of a living organism. Three different samples of the fruit fly, Drosophila melanogaster, are on display for observation. One sample of flies are normal, while two of the others have been genetically altered. Normal fruit flies have a brown-colored body, straight wings and red eyes. One sample of the mutated fruit flies has stumpy wings because the DNA responsible for the development of wings is missing. The other mutant sample has a yellow body because a single unit has been exchanged for another in the DNA for body pigment. Just as the fly's body color is determined by DNA, so is a human's body color. However, it is more than one gene that determines skin color in both flies and humans. It's often thought that changes (mutations) in DNA are bad but this is not necessarily true. Mutation can have negative, positive or neutral effects on a living organism.

DNA Molecules Model

This model shows a portion of the largest molecule in your body, DNA. The ladder of bases going up the middle and the sugar-phosphate backbones coiling up the outside are easily identified. Below the model are four tubes of DNA from four different organisms: human, fly, potato, and bacteria. Visitors notice that although the organisms are different, their DNA looks the same. Every living thing has DNA molecules composed of the same four units: adenine, cytosine, guanine, and thymine. Each unit is attached to a sugar and a phosphate molecule. If all living things have DNA molecules, why are species different? The answer is in the sequence of units. While the units (A, C, G, T,) are the same in all DNA, the sequence of the units is different for every individual. People look different from one another because of the minor differences in their DNA sequences. Other organisms have very different DNA sequences from us. The more DNA sequences you share with another organism, the more closely related you are. Identical twins have exactly the same DNA sequence.

Molecules for Reproduction : Computer Interactive

Visitors choose one of four organisms and step through a series of magnified images from the organism to their DNA molecules. Although the organisms are different, they all have DNA.

Your DNA and Your Traits

Our own unique DNA sequence and the environment work together to make us look and behave as we do. At this computer exhibit, visitors examine and catalog eight of their genetic traits that are influenced by their DNA sequence. Because everyone has a distinct DNA sequence and grows up in different environments, we are all unique individuals. Even identical twins which have exactly the same DNA sequence are exposed to different environmental conditions and, as a result, they will look and behave differently.

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