In prokaryotes during abortive initiation, the polymerase synthesizes a series of short transcripts. In eukaryotes, promoter escape involves;

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#Question id: 28955

#Unit 7. System Physiology – Animal

which of the following is correct about the secretion of primary hormone by the thyroid is___

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#Question id: 31373

#Unit 2. Cellular Organization

Which of the following protease breaking the cohesin circles and allowing sister chromatids to be pulled apart by the spindle apparatus that is pulling them toward opposite spindle poles?

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#Question id: 29003

#Unit 7. System Physiology – Animal

Parathyroid cell membrane contains___

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#Question id: 7097

#Unit 5. Developmental Biology

What property of the mammalian embryo permits the production of chimeric mice?

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#Question id: 15834

#Unit 8. Inheritance Biology

You are interested in a new type of autosomal dominant mutation that gives purple eyes in Drosophila. You have a true-breeding purple-eyed line carrying a mutation that you call pr-1. You have isolated a second purple-eyed mutation that you call pr-2, which you have established in a true-breeding line that also carries a recessive marker st, which gives stubby legs. You cross a fly from the pr-1 line to a fly from the st, pr-2 line producing F1 females which you then cross to males from a true breeding st line (normal eyes). From this cross, 1000 progeny flies can be categorized into four different phenotypic classes:

                             

Normally, 3-factor crosses give eight different phenotypic classes, why does this particular cross give only four?