Gene Expression and Lac Operon Quiz

What is gene expression?

• The process of copying DNA into DNA

• The process of turning genes “on” and “off” to produce proteins or RNA

• The replication of genetic material during cell division

• The removal of introns from mRNA

Why is regulating gene expression important for cells?

• It allows cells to use energy more efficiently

• It helps cells respond to environmental changes

• It ensures proper protein production at the right time and location

• All of the above

What is an operon?

• A group of genes controlled by multiple promoters

• A single gene encoding several unrelated proteins

• A cluster of genes controlled by one promoter and operator

• A regulatory sequence in eukaryotic cells

In bacteria, gene regulation mainly occurs at the level of:

• DNA replication

• Transcription

• Translation

• Protein degradation

The lac operon in E. coli is an example of:

• A repressible operon

• A constitutive operon

• An inducible operon

• A permanently inactive operon

What molecule acts as an inducer in the lac operon system?

• Glucose

• Tryptophan

• Allolactose

• Fructose

The lacZ gene encodes which enzyme?

• RNA polymerase

• β-galactosidase

• Lactose permease

• Transacetylase

What is the function of β-galactosidase?

• Transports lactose into the cell

• Converts lactose into glucose and galactose

• Synthesizes tryptophan

• Binds to the operator region

Which gene of the lac operon codes for the lactose transport protein?

• lacZ

• lacA

• lacI

• lacY

Which of the following statements about lacA is correct?

• It encodes β-galactosidase

• It encodes transacetylase

• It codes for the repressor protein

• It is essential for lactose metabolism