Problem 5 - AP Psychology Premium Prep 2021

Question

During post-translational modification, the polypeptide from a eukaryotic cell typically undergoes substantial alteration that results in (A) excision of introns (B) addition of a poly(A) tail (C) formation of peptide bonds (D) a change in the overall conformation of a polypeptide

Step-by-Step Solution

Answer

The correct option for the alteration that a polypeptide typically undergoes during post-translational modification in a eukaryotic cell is \( (D) \) a change in the overall conformation of a polypeptide.

Step 1: Understand post-translational modification

Post-translational modification is a process that occurs in eukaryotic cells after the translation of a polypeptide. During this process, the polypeptide undergoes various modifications such as foldings, additions or removal of chemical groups or amino acids to improve its functionality, stability, and localization. The purpose of these modifications is to ensure that the polypeptide can function correctly and interact with other molecules.

Step 2: Analyze each option

Now let's analyze each option and determine which one represents a process that occurs during post-translational modification: (A) Excision of introns: Introns are non-coding regions of a gene that are removed during RNA splicing, which is a process that occurs before translation. So, excision of introns is not part of post-translational modification. (B) Addition of a poly(A) tail: The poly(A) tail is added to the 3' end of the mRNA molecule during RNA processing, which also occurs before translation. Therefore, this option is not part of post-translational modification. (C) Formation of peptide bonds: Peptide bonds form between amino acids during the translation process when a ribosome synthesizes a polypeptide chain. So, the formation of peptide bonds is not a post-translational modification. (D) A change in the overall conformation of a polypeptide: Post-translational modifications can indeed lead to changes in the conformation of the polypeptide, such as folding, which affects its functionality, stability, and localization. Thus, this option is related to the post-translational modification process.

Step 3: Identify the correct option

Based on the analysis in the previous step, the correct option for the alteration that a polypeptide typically undergoes during post-translational modification in a eukaryotic cell is (D) a change in the overall conformation of a polypeptide.