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How do steroid hormones exert their action?

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Steroid hormones exert their action by initially entering a target cell's plasma membrane and then binding with specific receptors before translocating to the nucleus to initiate or alter the expression of a gene in the production of new proteins. These hormones are insoluble in water and require plasma carriers for transportation to their target sites, states the University of New Mexico.

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Hormones are regulatory chemicals that are mainly secreted by the endocrine glands. Depending on how they impact their target cells, hormones can be classified into three types: peptide, amine and steroid. Each of these hormonal types has its own mechanism of action, which pertains to a series of interactions through which the hormone induces its biological effects.

Steroid hormones have to first detach themselves from their carrier proteins before they can pass through a target cell's plasma membrane, which forms the boundary between the cell's external surroundings and its internal environment. The hormones then form a conjugate with specific steroid receptors, which can be found in the cytoplasm, or the region outside the nucleus. Three special properties of the receptor-hormone complex are specificity, low capacity and high affinity, which refers to bond strength, notes McGraw-Hill Education. The complex then moves to the nucleus to bind with deoxyribonucleic acid, or DNA, which triggers genetic transcription. That in turn serves as the initial step for genetic expression. This event results in the production of new components of ribonucleic acid called mRNA, which is responsible for coding a new set of proteins.

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