Gyrases are A2B2 heterotetramers in which the B subunits bind and hydrolyze ATP and the A subunits mediate the double-strand cleavage, strand passage, and reunion reactions.

The eukaryotic type II topoisomerases are homologous to gyrases but with their A and B subunits fused so that they are homodimers.

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#Unit 7. System Physiology – Animal

Renal plasma clearance is the volume of plasma from which a substance is completely removed by the kidney in a given amount of time (usually minutes).

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#Unit 5. Developmental Biology

A stem cell retains the ability to divide and re-create itself while also having the ability to generate progeny capable of specializing into a more differentiated cell type. 

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#Unit 10. Ecological Principles

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#Unit 13. Methods in Biology

Antigen can be detected or measured by a sandwich ELISA .In this technique, the antibody (rather than the antigen) is immobilized on a microtiter well. 

A sample containing antigen is added and allowed to react with the immobilized antibody. After the well is washed, a second enzyme- linked antibody specific for a different epitope on the antigen is added and allowed to react with the bound antigen

After any free second antibody is removed by washing, substrate is added, and the colored reaction product is measured.

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#Unit 4. Cell Communication and Cell Signaling