Operon Home Page

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This is a simple tutorial which may help you better understand the lac operon. Instead of memorizing all of the many possible genotypes and their workings, it is better to learn the steps needed to find the answer. You should then be able to answer questions about any genotype.

The steps are given on page 49 of the workbook and here: operonWorkbook2.gif.

There are 5 genotypes given; each appears twice, with lactose absent and lactose present.

Navigate via the yellow buttons. You may also access the list from the table below.

Question Number

Lactose is:

kind of genotype

01question.html

absent

single chromosome; mutant repressor gene

02question.html

present

single chromosome; mutant repressor gene

03question.html

absent

single chromosome; mutant operator

04question.html

present

single chromosome; mutant operator

05question.html

absent

single chromosome; mutant Z gene

06question.html

present

single chromosome; mutant Z gene

07question.html

absent

two chromosomes; mutant I and Z in trans

08question.html

present

two chromosomes; mutant I and Z in trans

09question.html

absent

two chromosomes; mutant O and Z in trans

10question.html

present

two chromosomes; mutant O and Z in trans