Question

7 Questions Ahead

1. What does it mean for genes to be regulated? In other words, what is gene regulation?

2. The type of gene regulation that uses an operon occurs in which type of cells, eukaryotes or prokaryotes?

3. What do we call the sequence of DNA where RNA polymerase can bind? (As a reminder, RNA Polymerase is the enzyme that is needed to start transcription, the first part of protein synthesis, which makes mRNA.)

4. An operator is a sequence of DNA found next to a promoter and is necessary to make mRNA. What happens if a repressor attaches to the operator?

5. The Lac Operon example shows how bacteria regulate the production of enzymes that break down lactose. The Lac Operon has a promoter, an operator and how many genes that code for enzymes that break down lactose (as sugar)?

6. LacI is an important part of the Lac Operon. Explain what happens when there is no lactose present.

7. Explain what happens when lactose is present.

Answer 1

1) Gene regulation refers to the process by which the expression of a gene is controlled. Expression refers to the process by which the genetic information in a gene is used to make a protein or RNA molecule. Gene regulation can control when a gene is turned on or off, as well as how much of a protein or RNA molecule is made.

2) The type of gene regulation that uses an operon occurs in prokaryotic cells, such as bacteria.

3) The sequence of DNA where RNA polymerase can bind is called a promoter.

4) An operator is a sequence of DNA found next to a promoter that is necessary to make mRNA. If a repressor attaches to the operator, it blocks the RNA polymerase from binding to the promoter, preventing transcription and the production of mRNA.

5) The Lac Operon has a promoter, an operator, and three genes that code for enzymes that break down lactose (as sugar).

6) When there is no lactose present, the repressor protein (LacI) binds to the operator, blocking the RNA polymerase from binding to the promoter and preventing the transcription of the genes that code for the enzymes needed to break down lactose.

7) When lactose is present, a molecule called allolactose binds to the repressor protein, causing it to release from the operator. This allows the RNA polymerase to bind to the promoter and start transcription, resulting in the production of the enzymes needed to break down lactose. This helps the bacteria utilize lactose as a source of energy and nutrients.