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Multiple Choice
Which is a post-translational modification of a polypeptide?
A
Removal of introns and splicing of exons
B
Formation of a polysome that allows simultaneous formation of many polypeptides from one mRNA transcript
C
The growing polypeptide signals the ribosome to attach to the ER.
D
Cleavage of a polypeptide into two or more chains
Verified step by step guidance
1
Understand the concept of post-translational modification: This refers to the chemical changes that occur to a polypeptide after it has been synthesized during translation. These modifications are crucial for the protein's final function and activity.
Identify the types of post-translational modifications: Common modifications include phosphorylation, glycosylation, ubiquitination, acetylation, and cleavage. Each of these modifications can alter the protein's function, location, or stability.
Differentiate between post-translational modifications and other cellular processes: Processes like removal of introns and splicing of exons occur during RNA processing, not after translation. Similarly, the formation of a polysome and ribosome attachment to the ER are part of translation and protein targeting, respectively.
Recognize cleavage as a post-translational modification: Cleavage involves cutting the polypeptide chain into smaller fragments, which can be necessary for activation or function. This is a common post-translational modification.
Apply this understanding to the problem: Given the options, identify that cleavage of a polypeptide into two or more chains is the correct example of a post-translational modification, as it occurs after the polypeptide has been synthesized.