Does the nuclear-to-cytoplasmic ratio increase (I) or decrease (D) during cleavage in early vertebrate development? Would you expect tetraploid embryos to undergo the maternal-zygotic transition earlier (E) or later (L) compared to diploids? If the availability of a transcription regulatory protein determines the timing of this transition, should the protein be a transcriptional activator (A) or repressor (R)? Write down your answer as a three-letter string using the letters in the parentheses above, e.g. IEA.

Question

Quizplus · Accepted Answer

Rapid cleavage increases total DNA without a concomitant increase in the total cytoplasmic volume, thereby increasing the ratio of DNA to diffusible repressors. This ratio reaches a threshold at the maternal-zygotic transition (MZT). This occurs after fewer rounds of cell division if the cells are polyploid.

Does the Nuclear-To-Cytoplasmic Ratio Increase (I) or Decrease (D) During