Temperature changes can have dramatic effects on microscopic life forms. Scientists incubate microbes at different temperatures for several reasons. One reason is that different microbes grow best at different temperatures. A second reason is that the scientist is trying to generate a temperature-sensitive mutant so that she can generate a mutated protein that can be easily turned off via changes in temperature. A third reason is that the scientist is activating the temperature-sensitive protein so that she can study the effects of the inactivated or activated protein.