Chapter 32, Problem 1P

Interpretation Introduction

Interpretation:

The physiological benefits and characteristics of each of the major class of hormones, such as polypeptide, steroid and amino acid-derived hormones need to be compared.

Concept Introduction :

Amino acids are organic compounds containing amino as well as acidic groups. The general molecular formula of an amino acid is as follows:

  ${\text{H}}_{\text{2}}\text{N-CH}\left(R\right)-\text{COOH}$

Here, R is different group for different amino acids. If there is more than one amino group present in an amino acid, they are considered as basic amino acids, and if there is more than one carboxylic group, then they are considered as acidic amino acids.

Answer to Problem 1P

Steroid hormones are the hormones, which control the gene expression. They help in controlling the metabolic processes, inflammatory processes. Some steroid hormones are responsible for maintaining osmolarity. The sex hormones are also steroid hormones; hence, they help in maintaining the sexual characteristics.

Polypeptide hormones include the largest class of hormones. They have insulin as a member.

The thyroid hormones regulate gene expression and include thyroxine and triiodothyronine.

Explanation of Solution

The main functions of steroid hormones are to regulate the metabolism, the inflammatory processes, and to maintain the water and salt balances. These hormones are derivative of cholesterol and control the sexual functions. The ligand-gated ion channels are regulated by these hormones. Steroid hormones are also capable of controlling gene expression by acting as the transcription regulators within the nucleus of the cell. The time needed for both procedures is not the same.

The hormones with the largest class are included in the polypeptide hormones and insulin is also a member. These hormones have three same characteristics:

• The synthesis of the secreted polypeptide hormone is achieved by using the single sequence.
• The synthesis of peptide hormone initially takes place by the formation of preprohormones which are further activated through proteolysis.
• The third common characteristics among all the polypeptide hormone is that, the number of dissimilar peptide hormones might be produced with single preprohormone.

There are two kinds of amino acid derivative hormones namely thyroid and catecholamine hormone. They are formed from tyrosine (amino acid) and function because of the creation of 2^nd messenger. The surface receptors bind the catecholamine hormones which are comprised of epinephrine and norepinephrine. The thyroid hormones controls gene expression and contain triiodothyronine and thyroxine.