Consider the following scenario:

Gene-Z is a transcription factor required for transcribing the genes that contribute to populating the motor cortex with the proper number of neurons. Mutant mice for Gene-Z have 50% fewer motor neurons than controls (non-mutants). You genetically engineer a transgenic DNA construct that acts as a dominant negativeto Gene-Z.

You transfect an embryonic mouse brain with this dominant negative and measure that all motor neurons get and expressed this construct. What would you expect the number of neurons in the transfected brain to be if the dominant negative works with 100% efficacy, and a normal motor cortex has 100,000 cells in the region you are examining?

Which of the following statements about the function of transcription factors is not true?

Which of the following is true?

I. Transcription factors typically bind directly to the genes that they regulate.

II. Transcription factors can bind enhancer and promoter regions upstream of the genes they regulate.

III. In eukaryotes, transcription factors frequently associate with coactivators.

IV. Transcription factors can either upregulate or downregulate transcription of a gene.