Which of the answer choices is/are an example of post-translational modification?
1. marking proteins for enzymatic destruction
2. addition of a phosphate group to the side chains of amino acids such as serine, threonine, or tyrosine
3. All of these choices are correct.
4. addition of one or more sugar molecules to the side chains of some amino acids
5. assistance by chaperons in folding of newly translated proteins

4. addition of one or more sugar molecules to the side chains of some amino acids

Explanation:

Post-translational modification occurs after a polypeptide has been formed in the ribosomes after the translation of the mRNA. This involves the addition of other molecules to the chain other than the sequence of amino acids.  Examples of post-translational modification are the processes of phosphorylation  - adding a phosphate molecule- and glycosylation – adding a carbohydrate molecule. These modifications have significance including enabling the folding to the polypeptide to desired 3D shape, playing a regulatory function and  stabilizing the protein.

The answer choices that are an example of post-translational modification is: 3. All of these choices are correct.

Translation refers to a cellular process through which a genetic code from a sequence of messenger ribonucleic acid (mRNA) molecule is translated (decoded) to a specific sequence of amino acids, during the synthesis of protein.

On a related note, post-translational modification (PTM) can be defined as the enzymatic modification of one (1) or more amino acids on a protein in ways that their structure and function are regulated, after the translation of a messenger ribonucleic acid (mRNA) molecule.

Some examples of post-translational modification (PTM) include the following:

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