What types of modifications can occur after a polypeptide chain has been complet
ID: 85750 • Letter: W
Question
What types of modifications can occur after a polypeptide chain has been completed by a ribosome? glycosylation removal of methionine hydrolysis addition of amino acids phosphorylation Suppose that a TAC codon in DNA is mutated to TAG. How would this mutation affect the synthesis of the polypeptide encoded by the DNA? The polypeptide would contain the wrong amino acid at the mutation site. The polypeptide would be shorter than normal. The polypeptide would not be affected because a mutation at the third position has no effect. The polypeptide would contain an extra amino acid following the mutation site.Explanation / Answer
Answer
1).
Phosphorylation
Glycosylation
Removal of methionine
Explanation.
Post-translational modifications can occur on the amino acid side chains or at the protein's C- or N- termini.
A. Phosphorylation
It is a very common mechanism for regulating the activity of enzymes and is the most common post-translational modification.
B. Glycosylation.
Manyeukaryotic proteins also have carbohydrate molecules attached to them in a process called glycosylation, which can promote protein folding and improve stability as well as serving regulatory functions.
C. Lipidation.
Attachment of lipid molecules is known as lipidation, often targets a protein or part of a protein attached to the cell membrane.
D. Other forms of post-translational modification consist of cleaving peptide bonds, as in processing a propeptide to a mature form or removing the initiator methionine residue.
E. The formation of disulfide bonds from cysteine residues may also be referred to as a post-translational modification
2). The polypeptide would contain the wrong amino acid at the mutation site.
Explanation
TAC would results methionine.
TAG would results isoleucine
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.