Homeobox (HoxHoxHox) genes play a crucial role in controlling the development of an organism's body plan. During embryogenesis, these master regulatory genes function in tandem with processes like mitosis and apoptosis to sculpt organs and limbs.
Which of the following statements correctly describes the molecular mechanism by which a protein encoded by a Hox Hox\,Hox gene regulates these target processes?
The protein acts as a nuclear transcription factor, using its homeodomain to bind to specific DNA regulatory sequences and stimulate or inhibit the transcription of target genes.
The protein functions as a transmembrane receptor on the cell surface, initiating an intracellular kinase cascade that directly phosphorylates mitotic cyclin-dependent kinases.
The protein behaves as an RNA-binding translation factor that directly recruits ribosomes to the 5′5'5′ cap of pro-apoptotic mRNAs, accelerating their translation in the cytoplasm.
The protein acts as a histone methyltransferase, chemically modifying chromatin structures specifically within the mitochondrial genome to trigger cytochrome c release.
30 exam-style questions on OCR A A Level Biology Cellular control. Each one has a worked solution and a mark scheme showing where the marks go.