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Post Translational Modification quiz #1

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  • What are post-translational modifications (PTMs), and why are they important for protein function?
    Post-translational modifications (PTMs) are covalent changes made to proteins after translation, such as methylation, acetylation, ubiquitination, phosphorylation, and others. They are important because they regulate protein activity, stability, localization, and interactions, allowing cells to control protein function after synthesis.
  • How does proteolytic cleavage serve as a post-translational modification, and what is its functional significance?
    Proteolytic cleavage is a post-translational modification where proteases or peptidases break specific peptide bonds in a protein. This process can activate proteins that are initially inactive after translation or remove inactive segments, thus regulating protein activity.
  • What does the term 'post-translational modification' (PTM) refer to in protein biochemistry?
    PTMs are covalent changes made to proteins after translation, altering their function, activity, or localization.
  • Name four common types of post-translational modifications discussed in the lesson.
    Common PTMs include methylation, acetylation, ubiquitination, and phosphorylation.
  • What is the main purpose of post-translational modifications in cells?
    PTMs regulate protein activity, stability, localization, and interactions, allowing precise control of protein function after synthesis.
  • Describe what happens during the process of hydroxylation as a PTM.
    Hydroxylation involves covalently adding a hydroxyl group to a protein.
  • How are disulfide bonds formed as a post-translational modification?
    Disulfide bonds form between the R groups of two cysteine residues, potentially linking two polypeptide chains.
  • What is ubiquitination and what does it involve?
    Ubiquitination is the covalent addition of a small protein called ubiquitin to a target protein.
  • What is proteolytic cleavage and what role does it play in protein activation?
    Proteolytic cleavage is the enzymatic breaking of specific peptide bonds in a protein, often activating proteins that are initially inactive after translation.
  • Which enzymes are responsible for proteolytic cleavage, and what is their function?
    Proteases or peptidases are enzymes that cleave peptide bonds at specific sites, enabling activation or inactivation of proteins.