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1.1 Peptide & Protein Hormone Synthesis — Test 1
Q1. Synthesis of a peptide-hormone precursor (preprohormone) on the ribosome is directed by a specific mRNA and occurs on the:✓ Rough endoplasmic reticulum
Q2. Removal of the signal peptide from a preprohormone in the rough ER produces the:✓ Prohormone
Q3. Final modification of the prohormone into the mature, active hormone occurs mainly in the:✓ Golgi complex
Q4. The mature peptide hormone is released from the cell by the process of:✓ Exocytosis
Q5. In insulin biosynthesis, conversion of proinsulin to insulin involves removal of the:✓ C-peptide
Q6. The A and B chains of mature insulin are held together by:✓ Two interchain disulfide bridges
Q7. Which one of the following is NOT formed after post-translational processing of pre-proglucagon?✓ beta-Lipotropin
Q8. Pro-opiomelanocortin (POMC) is the common precursor of all of the following EXCEPT:✓ Thyroid-stimulating hormone
Q9. The glycoprotein hormones TSH, LH, FSH and hCG share an identical subunit. Biological specificity is conferred by the:✓ beta subunit
Q10. Human chorionic gonadotropin (hCG) is best described as a:✓ Heterodimer with a smaller alpha and larger beta subunit
Q11. Compared with the active hormone, the initial translation product (preprohormone) is:✓ Larger
Q12. Prohormone convertases that process peptide-hormone precursors typically cleave at:✓ Paired basic residues (e.g. Lys-Arg, Arg-Arg)
Q13. Polypeptide hormones differ fundamentally from steroid hormones in that polypeptide hormones are:✓ Direct gene products synthesized from mRNA
Q14. Posterior-pituitary peptides ADH and oxytocin are packaged for transport down axons complexed with:✓ Neurophysins
Q15. Match the hormone with its chemical precursor and select the correct combination.✓ A-iii, B-i, C-ii
Q16. C-peptide measurement is clinically useful mainly because it:✓ Reflects endogenous insulin (beta-cell) secretion
Q17. During synthesis of a secreted peptide hormone, the signal peptide functions to:✓ Target the nascent chain into the ER lumen
Q18. Before regulated release, mature peptide hormones are stored within the cell in:✓ Secretory (storage) granules
Q19. A single precursor giving rise to several different bioactive peptides in different tissues is best exemplified by:✓ Pro-opiomelanocortin (POMC)
Q20. Which feature is characteristic of peptide-hormone (but NOT steroid-hormone) producing cells?✓ Abundant rough ER and storage secretory granules