A pharmaceutical researcher performs preclinical testing on a novel chemotherapeutic drug. When rat embryos are exposed to this drug during an early stage of organogenesis, they develop severe skeletal malformations. Further genetic analysis reveals that the drug causes mutations in numerous homeobox genes containing highly conserved 180 base pair DNA sequences. The genes affected by this drug most likely code for which of the following proteins?

Question

A pharmaceutical researcher performs preclinical testing on a novel chemotherapeutic drug.  When rat embryos are exposed to this drug during an early stage of organogenesis, they develop severe skeletal malformations.  Further genetic analysis reveals that the drug causes mutations in numerous homeobox genes containing highly conserved 180 base pair DNA sequences.  The genes affected by this drug most likely code for which of the following proteins?

Quizplus · Accepted Answer

11ec160b_3777_0114_9249_81d64df90a67_MD0001_00 A homeobox is a highly conserved DNA sequence that is usually about 180 nucleotides in length. A gene containing a homeobox sequence is called a homeobox or hox gene. These genes typically code for transcription factors that bind to regulatory regions on DNA, altering the expression of genes involved in the segmental organization of the embryo. Proper morphogenesis ensures that tissues, organs, and structural elements of the body are formed in the correct position along the cranio-caudal axis. Homeobox gene mutations interrupt this developmental process, often resulting in severe abnormalities such as skeletal malformations and improperly positioned limbs and appendages. (Choices A, B, C, D, and F) Homeobox genes do not typically encode cell surface receptors, cytoplasmic enzymes, DNA replication enzymes, structural proteins, or transport proteins. Educational objective: Homeobox genes encode DNA-binding transcription factors that play an important role in the segmental organization of the embryo along the cranio-caudal axis. __________ References: The regulation of Hox gene expression during animal development. (http://www.ncbi.nlm.nih.gov/pubmed/24046316)

A Pharmaceutical Researcher Performs Preclinical Testing on a Novel Chemotherapeutic