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TLS Online TPP Program

#Id: 9380

Innate behaviour

Reflex - Allow us to move in response to something in the environment.

The reflex which causes us to close our eyes when something flashes towards us, or to withdraw a foot when we step on a sharp object.

#Unit 11. Evolution and Behavior #Behavior #Part B Pointers
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TLS Online TPP Program

#Id: 1507

#Unit 2. Cellular Organization

Each α or β monomer has a binding site for one molecule of GTP.
TLS Online TPP Program

#Id: 1508

#Unit 2. Cellular Organization

The GTP that is bound to α-tubulin is physically trapped at the dimer interface and is never hydrolyzed.
TLS Online TPP Program

#Id: 1509

#Unit 2. Cellular Organization

GTP-binding site on the β-subunit is at the surface of the dimer and GTP bound by the β-subunit can be hydrolyzed.
TLS Online TPP Program

#Id: 1510

#Unit 2. Cellular Organization

A microtubule is a hollow cylindrical structure built from 13 parallel protofilaments, each composed of αβ-tubulin heterodimers stacked head to tail and folded into a tube.
TLS Online TPP Program

#Id: 1511

#Unit 2. Cellular Organization

Tubulin dimers in which the β-subunit has bound GTP are added preferentially to (+) end of the microtubule.
TLS Online TPP Program

#Id: 1512

#Unit 2. Cellular Organization

In a microtubule,
The end with exposed β-subunits is the (+) end
The end with exposed α-subunits is the (−) end