30 Questions
Which of the following is a nonessential amino acid that can be made from a glycolytic intermediate?
Serine
Which enzyme is responsible for the conversion of 3-phosphoserine to serine?
Phosphoserine phosphatase
Which amino acid can be made from serine?
Glycine
What is the primary use of amino acids in the body?
Building blocks for protein synthesis
What is the purpose of intracellular protein degradation?
All of the above
How can degrading proteins regulate biological and metabolic processes?
All of the above
Which of the following is true about protein degradation?
Protein degradation can occur from the breakdown of ingested proteins or cellular proteins
What is the recommended daily protein requirement for the average adult?
0.8 g/kg of body weight
What is nitrogen balance?
The amount of nitrogen ingested is equal to the amount of nitrogen excreted
When does a negative nitrogen balance occur?
During starvation or physical trauma
What is the chemical score used to assess in the protein quality of food?
The ratio of essential amino acids in particular foods to the reference diet
Why are some amino acids considered essential and must be obtained from the diet?
Because they cannot be synthesized by the body
Which organelle is responsible for the degradation of obsolete or unused proteins in the cytoplasm?
Lysosome
What is the function of the regulatory cap complex in the proteasome?
To control access to the proteasomal interior
Which enzyme type is responsible for removing ubiquitin from target proteins?
Deubiquitinating enzyme (DUB)
What is the pH range of lysosomes, where they function optimally?
4-5
Which of the following diseases is NOT associated with proteins involved in the ubiquitin conjugating pathway?
Multiple myeloma
What is the first therapeutic proteasome inhibitor approved in the US for the treatment of relapsed multiple myeloma?
VELCADE (bortezomib)
Which of the following is true about protein degradation?
Protein degradation allows the cell to maintain sensitivity to cellular signals.
Which pathway is involved in the degradation of intracellular proteins?
Ubiquitin-proteasome pathway
What is the role of ubiquitin in protein degradation?
Ubiquitin is a tag that marks proteins for destruction.
What is the function of E3 in the ubiquitin-protein complex formation?
E3 transfers ubiquitin from E2 to a lysine residue in the target protein.
What is required for the degradation of a target protein?
Polyubiquitination using K48 linkages within the ubiquitin protein.
What happens to ubiquitin-tagged proteins in proteasomal degradation?
They are degraded by the proteasome.
Which of the following is NOT a source of amino acids for cellular metabolism?
Essential amino acids
What is the purpose of intracellular protein degradation?
To regulate cholesterol biosynthesis
Which pathway is responsible for the degradation of proteins through ubiquitin conjugation and proteasomal degradation?
Ubiquitin-proteasome pathway
What is the therapeutic role of proteasome inhibitors in the treatment of cancer?
To induce apoptosis in cancer cells
Which of the following is an example of lysosomal degradation of proteins?
Autophagy
What are two methods by which the protein quality of foods can be assessed?
Dietary protein digestion and nitrogen balance
Test your knowledge on protein degradation and learn about the role of serine, a nonessential amino acid, in the production pathway. Explore the connection between serine and the glycolytic intermediate 3-phosphoglycerate.
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