Chapter 4, Problem 29P

Summary Introduction

To analyze:

Dr. Sophila observed that fruit flies with normal behavior kept at ${\text{22}}^{\text{°}}\text{C}$ show abnormal behavior (paralyzed) when moved to ${\text{30}}^{\text{°}}\text{C}$ temperature. After returning to ${\text{22}}^{\text{°}}\text{C}$ temperature, they again restore their ability to move. The cross between fruit flies with unusual behavior shows $812$ progenies, among which $598$ are unusual and $214$ are normal fruit flies. By using the above information, analyze the unusual behavior of the fruit flies and explain the condition responsible for the change in the behavior of the flies.

Introduction:

The fruit flies in the given question show different phenotypes at different temperatures. The probable cause for this might be the inactivity of the gene at a high temperature which is important for the normal behavior or phenotype. Therefore, an organism showing temperature-sensitive mutation is called a temperature sensitive mutant. Temperature sensitive mutant grown in the permissive condition means the mutated gene product behaves normally at the low temperature and shows altered behavior at high temperature. The temperature at which they show normal behavior is called permissive temperature. A temperature sensitive mutant returns to its normal behavior if placed in permissive temperature.