Gene Expression and Regulation

What is the outcome of gene expression?

• A functional protein or RNA molecule

• A DNA molecule

• A carbohydrate

• A lipid

Why is gene regulation essential for cells?

• To ensure all genes are constantly active.

• To prevent cells from dividing too rapidly.

• To produce only the necessary proteins at the correct time and place.

• To protect DNA from mutations.

In which type of cell can transcription and translation occur simultaneously in the cytoplasm?

• Eukaryotic cells only

• Prokaryotic cells only

• Both prokaryotic and eukaryotic cells

• Neither prokaryotic nor eukaryotic cells

What is the primary function of a repressor protein in an operon?

• To enhance the binding of RNA polymerase to the promoter.

• To break down mRNA molecules after transcription.

• To block RNA polymerase from initiating transcription.

• To transport proteins out of the cell.

In the lac operon, what happens when lactose is present in the environment?

• The repressor protein blocks transcription, preventing enzyme creation.

• The repressor protein cannot block transcription, leading to enzyme creation.

• The genes are permanently turned off, regardless of lactose presence.

• Lactose directly binds to the DNA, initiating transcription.

How does histone methylation typically affect gene transcription?

• It loosens DNA packing, making genes more accessible for transcription.

• It adds phosphate groups to DNA, activating transcription factors.

• It tightens DNA packing, blocking transcription factors and preventing transcription.

• It removes introns from mRNA, enhancing gene expression.

During post-transcriptional regulation in eukaryotes, what happens to introns in the mRNA molecule?

• Introns are translated into non-functional protein segments.

• Introns are removed, and the remaining exons are joined together for translation.

• Introns are modified and become part of the final protein structure.

• Introns signal the mRNA to be immediately degraded.

What is the effect of phosphorylating eIF-2 (eukaryotic initiation factor-2) on translation?

• It enhances the binding of tRNA to the ribosome, speeding up translation.

• It changes the shape of eIF-2, preventing it from initiating translation.

• It causes the mRNA to be degraded before translation can begin.

• It activates other initiation factors, leading to increased protein synthesis.