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Mechanisms of action of steroid hormones

  • These are lipid soluble hormones so they can pass easily through cell membrane and enter into target cells.

  • Inside the cell they bind to specific cytoplasmic receptor proteins. Thus hormone receptor complex is formed

  • Activated receptor-hormone complex diffuses into the nucleus and binds with the specific chromosome (DNA).

  • Binding of the receptor hormone complex to DNA changes the rate of transcription of a particular gene to form messenger RNA.

  • The specific messenger RNA enters the cytoplasm and directs the ribosomes to synthesis specific proteins (translation). Further actions are exerted by these proteins. This whole mechanism is slow.

Therefore… (309 more words) …

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Hormones, Enzymes and Vitamins

Table showing the Differences between Hormones and Enzymes

Differences between Hormones and Enzymes

Sn.

Hormones

Enzymes

1.

Are produced by one group of cells and

via blood reaches to target cells for

their action.

.

May act at the site where they are produced

or carried to another site for their action.

2.

They can be proteins, peptides, steroids

or amino acid derivatives.

They are simple proteins.

3.

Have low molecular weight.

Have very high molecular weight.

4.

Effective in low concentration.

Can also act in low concentration, but

the rate of enzyme catalyzed

reactions increases with an increase in… (193 more words) …

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