Pearson, as an active contributor to the biology learning community, is pleased to provide free access to the Classic edition of The Biology Place to all educators and their students.
The purpose of the activities is to help you review material you have already studied in class or have read in your text. Some of the material will extend your knowledge beyond your classwork or textbook reading. At the end of each activity, you can assess your progress through a Self-Quiz.
To begin, click on an activity title.
Lab 2 Enzyme Catalysis
Mitosis and Meiosis
Plant Pigments and Photosynthesis
6-I Bacterial Transformation
6-II DNA Electrophoresis
Genetics of Organisms
Population Genetics and Evolution
10-I Cardiovascular Fitness
10-II Heart Rate in Daphnia
Biomembranes I: Membrane Structure and Transport
Biomembranes II: Membrane Dynamics and Communication
Cardiovascular System I: The Beating Heart
Cardiovascular System II: The Vascular Highway
Cell Structure and Function
DNA Structure and Replication
From Gene to Protein: Transcription
From Gene to Protein: Translation (Protein Synthesis)
Plant Structure and Growth
Properties of Biomolecules
Restriction Enzyme Digestion of DNA
The lac Operon in E. coli
Concept 7: The lac Inducer: Allolactose
Allolactose is called an inducer because it turns on, or induces the expression of, the lac genes.
The presence of lactose (and thus allolactose) determines whether or not the Lac repressor is bound to the operator.
Allolactose binds to an allosteric site on the repressor protein causing a conformational change. As a result of this change, the repressor can no longer bind to the operator region and falls off. RNA polymerase can then bind to the promoter and transcribe the lac genes.