Choose the molecules in eukaryotic cells that regulate gene expression.

A. recombinant DNA
B. transcription factors
C. ATP
D. polymerase factors

Specialization takes place when cells in your hair follicles produce the protein keratin, which is a primary component of hair, while cells in your liver do not produce keratin. Why does this specialization occur?

A. Hair follicle cells contain different genes from liver cells.
B. Different types of genes are activated in liver cells and hair follicle cells.
C. Hair follicle cells do not produce DNA, but liver cells do.
D. Hair follicle cells contain recombinant DNA.

What is the best explanation for why scientists involved in biotechnology sometimes insert the DNA of one organism into a second organism?

A. to increase meiosis
B. to create a new species
C. to make more efficient cell organelles
D. to cause the second organism to produce proteins