A bacterial type II enzyme, called either topoisomerase II or DNA gyrase, can introduce negative supercoils (decrease Lk). It uses the energy of ATP to accomplish this.

To alter DNA linking number, type II topoisomerases cleave both strands of a DNA molecule and pass another duplex through the break.

TLS Online TPP Program

#Id: 9714

#Unit 4. Cell Communication and Cell Signaling

Ste11 analogous to Raf and other mammalian MEK kinase (MEKK) proteins.

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#Id: 1493

#Unit 4. Cell Communication and Cell Signaling

MDM2 inhibits p53  by targeting it to the ubiquitin-dependent proteosomal degradation pathway.

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#Id: 2584

#Unit 7. System Physiology – Animal

There are two components for Cl− reabsorption:

Transcellular

Paracellular

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#Id: 6800

#Unit 3. Fundamental Processes

the RNA guide strand recruits RISC to a target RNA. It has been argued that the length of 22 nucleotides is just long enough to specify a single target sequence uniquely in the large genomes of complex eukaryotes using RNA–RNA base pairing.

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#Id: 7609

#Unit 5. Developmental Biology

Slow Block to polyspermy

When the cortical granules fuse with the egg cell membrane, they release protein-digesting enzymes that modify the zona pellucida proteins such that they can no longer bind sperm