Question

In the experiment by Davis et al., only fibroblast cells that took up the cloned myoD gene differentiated into muscle cells. This is because

A. only those cells contained muscle-cell-specific enhancer sequences.
B. MyoD is a transcription factor that turned on muscle-specific genes such as myosin
C. MyoD is a transcription factor that shut off fibroblast specific genes, allowing the muscle cell characteristics to show up
D. MyoA and MyoH are transcription factors that shut off muscle-specific genes
E. myoD is the gene for myosin and the presence of myosin converts the fibroblast into a muscle cell

Answer 1

Fibroblast cells with the cloned myoD gene differentiated into muscle cells due to MyoD being a transcription factor that activates muscle-specific genes.

Step-by-step explanation:

In the experiment by Davis et al., only fibroblast cells that took up the cloned myoD gene differentiated into muscle cells because MyoD is a transcription factor that turned on muscle-specific genes such as myosin.

This is key because to differentiate, a cell must manipulate gene expression, with transcription factors binding to DNA to either promote or inhibit transcription. MyoD binds to and activates the transcription of genes necessary for muscle cell differentiation, leading to the production of muscle-specific proteins and resulting in the fibroblast cells taking on muscle cell characteristics.