RNA polymerase II terminates after a short distance; small oligonucleotides of 4–5 nt are unstable; crystal structures of these RNA/DNA hybrids are unordered. Only longer hybrids have proper base pairing. The short RNA products are degraded rapidly. The suggestion is that this abortive initiation is a form of promoter proofreading.

TLS Online TPP Program

#Id: 3632

#Unit 3. Fundamental Processes

The first two bases of an mRNA codon always form strong Watson-Crick base pairs with the corresponding bases of the tRNA anticodon and confer most of the coding specificity.

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#Id: 9204

#Unit 11. Evolution and Behavior

Evolution by natural selection occurs if variation must lead by Ecotypes. 

Ecophene is not be selected by natural selection

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#Id: 7596

#Unit 5. Developmental Biology

Mouse cumulus cells also secrete a substance, CRISP1, that attracts sperm and hyperactivates them through CatSper channels

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#Id: 9703

#Unit 4. Cell Communication and Cell Signaling

An a haploid cell secretes the a mating factor and has GPCRs for the α factor on its cell surface; an α cell secretes the α factor and has GPCRs for the a factor.

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#Id: 7470

#Unit 4. Cell Communication and Cell Signaling