The lactose (lac) operon in E. coli is a gene that helps break down lactose in the cell. If there is no lactose present, the operon is repressed. In 3-5 sentences, explain how the lac operon is used and repressed in cells. Use the following words in your response: operon, operator, repressor, RNA polymerase, and transcribe/transcription. (4 points)

Answer 1

The lac operon in E. coli is a set of genes that allows the bacteria to metabolize lactose when it is present. In the absence of lactose, a repressor protein binds to the operator region of the operon, effectively blocking RNA polymerase from attaching and initiating transcription of the genes needed for lactose breakdown. When lactose is available, it binds to the repressor, causing a conformational change that releases it from the operator, allowing RNA polymerase to transcribe the operon genes. Thus, the lac operon is used to efficiently produce the necessary enzymes only when lactose is present.

Answer 2

Homozygous tall (TT) pea plants look the same as heterozygous tall (Tt) pea plants. Formulate a pollination experiment to identify whether a tall pea plant is homozygous or heterozygous. Explain your answer in 3-5 sentences.(4 points)