Question

A PREPROPROTEIN is ( check all that apply):

a contains a signal peptide

b secreted from the cell

c cleaved before it is active

d translated from unspliced pre-mRNAs

e in translated by ribosomes on the rough endoplasmic reticulum

Answer 1

A preproprotein contains a signal peptide, is often secreted from the cell, and must be cleaved before it becomes active. It undergoes modifications like the removal of its signal peptide and other posttranslational chemical modifications to become a functional protein.

Step-by-step explanation:

A preproprotein is a precursor to a functional protein that typically undergoes several processing steps before becoming an active protein. The correct statements about a preproprotein are:

• a contains a signal peptide
• b secreted from the cell
• c cleaved before it is active

These proteins contain a signal peptide that directs the protein to a specific cellular compartment, such as the rough endoplasmic reticulum (RER) where they are usually synthesized. After being directed to the RER, many of these proteins are secreted out of the cell. The signal peptide is typically removed, or the protein is otherwise cleaved, which is a step necessary for the protein to become active. This cleavage represents a form of posttranslational modification, which can also include phosphorylation, methylation, or glycosylation.