Chapter 28, Problem 1MCQ

The effect of a water-soluble peptide hormone such as insulin is generally quicker than that of a steroid hormone such as estrogen because

1. a. peptide hormones exert changes using molecules already present in the target cell.
2. b. steroid hormones trigger the synthesis of new proteins.
3. c. steroid hormones cannot pass through the cell’s plasma membrane.
4. d. Both a and b are correct.

Summary Introduction

Introduction:

Steroid hormones are fat soluble hormone and regulate the development of male and female sex characteristics. Amine hormone is synthesized from amino acids. The water-soluble hormone cannot cross the plasma membrane thus its receptors are present on the cell membrane.

Answer to Problem 1MCQ

Correct answer:

Water-soluble peptide hormone exerts a quick response than that of a steroid hormone because peptide hormones introduce changes using molecules already present in the target cell, whereas steroid hormones act by synthesizing a new protein. Therefore, option d. is correct.

Explanation of Solution

Reason for the correct statement

The receptor of peptide hormone does not readily pass through the cell membrane and they have receptors for peptide hormones on the cell surface of their target cells that trigger the change in cell metabolism. Steroid hormones alter the DNA transcription rate nucleus and change protein synthesis pattern and change the structure and metabolism of target cells.

Option d. is given as “both a and b are correct”.

As “different hormone actions exerted through changes in protein phosphorylation or through changes in gene expression. Different mechanism of action for peptide hormones working through membrane receptors, and steroids hormones working through nuclear receptors. ”, is the right answer.

Hence, option d. is correct.

Reasons for the incorrect statements:

Option a. is given as “peptide hormones exert changes using molecules already present in the target cell”.

Receptor for peptide hormones already present on target cell membrane and steroid hormones change the cell metabolism after binding to nuclear receptors. So, it is a wrong answer.

Option b. is given as “steroid hormones trigger the synthesis of new proteins”

Steroid hormones enter the cell by diffusion across the plasma membrane and bind to specific cytoplasmic receptor and translocation to the nucleus. In the nucleus, steroid hormones alter the gene transcription. So, it is a wrong answer.

Option c. is given as “steroid hormone cannot pass through the cell’s plasma membrane”.

Steroid hormones are fat soluble and can easily pass through the cell membrane. So, it is a wrong answer.

Hence, options a., b., and c. are incorrect.

Conclusion

Steroid hormones are soluble in the plasma membrane and readily enter the cytosol. Steroid bind to intracellular receptors, either in the cytosol or in the nucleus, the hormone receptor complex acts as a transcription factor which alters the gene products.