Final answer:
Peptide hormones are synthesized as preprohormones, which are larger precursors that undergo processing to become active hormones. This includes the synthesis of hormones like oxytocin and growth hormone as well as their modifications before becoming biologically active. The correct answer to the student's question is option 4) preprohormones.
Step-by-step explanation:
Peptide Hormones Synthesis
Peptide hormones are chains of amino acids that range in size and complexity. The synthesis of peptide hormones is similar to that of other body proteins, where DNA is transcribed into mRNA, which is then translated into an amino acid chain. The initial form of these hormones is typically not the active form that will be released into the bloodstream to exert its biological effects. Instead, these hormones are first synthesized as larger precursors.
The correct option for the initial synthesis of peptide hormones consisting of 50 or fewer amino acids is as preprohormones (option 4). These preprohormones undergo several modifications, including cleaving to form prohormones, and further processing to yield the active hormone. This multi-step process ensures that hormones are activated at the appropriate time and place, preventing premature activity that could disturb the delicate balance of physiological processes.
Examples of peptide hormones include oxytocin, antidiuretic hormone (ADH), growth hormone, and follicle-stimulating hormone (FSH). These hormones vary in size from relatively small peptides to larger polypeptides and glycoproteins. They are synthesized in the anterior pituitary gland, among other locations, and have roles in a broad range of physiological functions such as growth, metabolism, and reproduction.
In conclusion, the correct answer to the question is option 4) preprohormones.