Question

Which of the following is not a protein hormone?
A) Relaxin
B) HCG
C) Placental lactogen
D) Estradiol

Answer 1

Hormones are the endocrine glands secretions. These are the informational molecules secreted by the endocrine glands in response to changes in the external or internal environment and carried by the blood to another part where they stimulate specific physiological processes.

Complete answer:
Proteins are among the most important macromolecules of organisms. Some hormones are proteinaceous in nature e.g. insulin, parathyroid, etc. The Gonadotropic, somatotropic and thyrotropic hormones are secreted by the anterior lobe of the pituitary gland, insulin and glucagon hormones secreted by the pancreas and parathormone of parathyroids, human chorionic gonadotropin (HCG), human chorionic somatomammotropin (HCS) and rel; axin of placenta are protein hormones.

Relaxin is a protein hormone and is secreted by the corpus luteum during the later stages of pregnancy. It relaxes pubic symphysis and dilates the uterine cervix near the end of pregnancy for easy birth of the young one.

HCG stands for Human Chorionic Gonadotropin. It is a protein hormone which stimulates the corpus luteum of pregnancy to secrete progesterone until the end of pregnancy.
Placental lactogen is a placental hormone that is proteinaceous in nature which stimulates mammary growth.

Estradiol is the principal female sex hormone produce by ovarian follicles. They stimulate the development of female secondary sex characteristics at puberty and maintain them later during the reproductive years of adult life. They also regulate the menstrual cycle together with the gonadotropic hormones of the anterior pituitary.

So, the correct answer is option (D) Estradiol because it does not have a proteinaceous nature.

Note: The biochemical which is acted upon by an enzyme is called the substrate. In case two biochemicals are involved in a reaction, the same are called reactants. The substances produced in the reaction are termed as products. The final products are also called end products.