Directional Natural selection

Directional selection favors individuals at one extreme of a phenotypic distribution that have greater reproductive success in a particular environment.

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#Unit 7. System Physiology – Animal

“Organification” of Thyroglobulin- Iodination of tyrosine and formation of the thyroid hormones

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#Unit 7. System Physiology – Animal

Tyrosine is first iodized to monoiodotyrosine and then to diiodotyrosine. Then, more and more of the iodotyrosine residues become coupled with one another

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#Id: 5795

#Unit 7. System Physiology – Animal

TLS Online TPP Program

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#Unit 7. System Physiology – Animal

The major hormonal product of the coupling reaction is the molecule thyroxine (T4), which is formed when two molecules of DIT are joined together; the thyroxine then remains part of the thyroglobulin molecule.

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#Unit 7. System Physiology – Animal

Iodinated Tyrosines (MIT and DIT) are deiodinated by a microsomal iodotyrosine deiodinase, to recover iodine and bound tyrosines and recycle them for additional rounds of hormone synthesis.

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#Unit 7. System Physiology – Animal

The thyroid hormone receptor usually forms a heterodimer with retinoid X receptor (RXR) at specific thyroid hormone response elements on the DNA