MCQ Quiz-Exosomes

MCQ Quiz: Exosomes

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Exosomes are at the cutting edge of biotechnology, representing a paradigm shift in our understanding of intercellular communication. These nano-sized vesicles, once thought to be cellular debris, are now recognized as critical carriers of biological information. For PharmD students, the study of exosomes is vital, as they hold immense potential as next-generation diagnostic tools (“liquid biopsies”) and as natural, targeted drug delivery vehicles, promising to revolutionize therapeutic strategies.

1. Exosomes are a type of extracellular vesicle that originates from the:

  • Outward budding of the plasma membrane
  • Endosomal pathway via multivesicular bodies (MVBs)
  • Fragmentation of the cell during apoptosis
  • Direct secretion from the Golgi apparatus


Answer: Endosomal pathway via multivesicular bodies (MVBs)

2. Which of the following protein families is commonly used as a positive marker for identifying exosomes?

  • Albumins
  • Hemoglobins
  • Tetraspanins (e.g., CD9, CD63, CD81)
  • Kinases


Answer: Tetraspanins (e.g., CD9, CD63, CD81)

3. What is the approximate size range of an exosome?

  • 1-5 micrometers
  • 500-1000 nanometers
  • 30-150 nanometers
  • Less than 10 nanometers


Answer: 30-150 nanometers

4. The primary biological function of exosomes is believed to be:

  • Cellular waste disposal
  • Energy production for the cell
  • Intercellular communication by transferring cargo
  • Structural support for the cell membrane


Answer: Intercellular communication by transferring cargo

5. Which type of cargo found within exosomes has significant potential for use as a diagnostic biomarker?

  • Glucose and salts
  • Free-floating amino acids
  • microRNA (miRNA) and proteins
  • Water


Answer: microRNA (miRNA) and proteins

6. A “liquid biopsy” refers to the analysis of biomarkers from a bodily fluid. Exosomes are promising for this because they:

  • Are found in easily accessible fluids like blood and urine and reflect the status of their parent cell
  • Are only produced by healthy cells
  • Are large enough to be seen with a standard light microscope
  • Do not contain any nucleic acids


Answer: Are found in easily accessible fluids like blood and urine and reflect the status of their parent cell

7. In contrast to exosomes, microvesicles are formed by:

  • The fusion of multivesicular bodies with the cell membrane
  • The direct outward budding or blebbing of the plasma membrane
  • The breakdown of the nucleus
  • The endoplasmic reticulum


Answer: The direct outward budding or blebbing of the plasma membrane

8. What is a key potential advantage of using exosomes as a drug delivery system?

  • They are inherently immunogenic and trigger a strong immune response
  • They have a natural ability to cross biological barriers and are of biological origin
  • They can only deliver small molecule drugs
  • They are very easy to produce in large, pure quantities


Answer: They have a natural ability to cross biological barriers and are of biological origin

9. The process of loading a therapeutic agent (like siRNA or a small molecule drug) into an exosome is a major challenge in their development. This process is called:

  • Cargo loading or engineering
  • Exosome purification
  • Cell culturing
  • Western blotting


Answer: Cargo loading or engineering

10. Ultracentrifugation is a common laboratory method used for what purpose in exosome research?

  • To isolate exosomes from cell culture media or biological fluids
  • To load drugs into exosomes
  • To measure the biological activity of exosome cargo
  • To sequence the RNA inside exosomes


Answer: To isolate exosomes from cell culture media or biological fluids

11. Exosomes released from cancer cells can play a role in pathology by:

  • Suppressing tumor growth
  • Promoting metastasis by preparing a pre-metastatic niche
  • Making cancer cells more susceptible to chemotherapy
  • Triggering an anti-tumor immune response


Answer: Promoting metastasis by preparing a pre-metastatic niche

12. The lipid bilayer membrane of an exosome is important because it:

  • Allows the exosome to replicate
  • Protects its internal cargo from degradation
  • Is where the exosome’s DNA is stored
  • Makes the exosome rigid and inflexible


Answer: Protects its internal cargo from degradation

13. A key challenge in scaling up exosome production for clinical use is:

  • A lack of potential therapeutic applications
  • The difficulty in producing large quantities of consistent and pure exosomes
  • The fact that cells do not naturally produce exosomes
  • The refusal of the FDA to regulate them


Answer: The difficulty in producing large quantities of consistent and pure exosomes

14. Exosomes derived from which cell type are being heavily investigated for their inherent regenerative and immunomodulatory properties?

  • Red blood cells
  • Mesenchymal Stem Cells (MSCs)
  • Fully differentiated neurons
  • Cancer cells


Answer: Mesenchymal Stem Cells (MSCs)

15. To create an exosome that targets a specific cell type, researchers can engineer the exosome to:

  • Display a targeting ligand or antibody on its surface
  • Be much larger than normal
  • Carry a fluorescent protein
  • Have a negative electrical charge


Answer: Display a targeting ligand or antibody on its surface

16. Nanoparticle Tracking Analysis (NTA) is a technique used to characterize exosomes by measuring their:

  • Protein content
  • RNA sequence
  • Size distribution and concentration
  • Surface charge


Answer: Size distribution and concentration

17. The ESCRT (Endosomal Sorting Complex Required for Transport) machinery is involved in:

  • The isolation of exosomes via ultracentrifugation
  • The formation of multivesicular bodies and the sorting of cargo into exosomes
  • The loading of drugs into exosomes via electroporation
  • The final release of the exosome from the cell


Answer: The formation of multivesicular bodies and the sorting of cargo into exosomes

18. How do exosomes communicate with a recipient cell?

  • By binding to a surface receptor and triggering a signal
  • By fusing with the recipient cell’s membrane and releasing its contents
  • By being engulfed by the recipient cell (endocytosis)
  • All of the above


Answer: All of the above

19. A major advantage of using exosomes for drug delivery over synthetic nanoparticles is their:

  • Lower production cost
  • Larger size
  • Biological origin, which may lead to lower toxicity and immunogenicity
  • Simpler surface chemistry


Answer: Biological origin, which may lead to lower toxicity and immunogenicity

20. A “proteome” analysis of an exosome sample would aim to identify:

  • All the lipids in the membrane
  • All the proteins present
  • All the mRNA sequences
  • All the microRNA sequences


Answer: All the proteins present

21. A potential therapeutic application of exosomes in neurodegenerative diseases like Alzheimer’s is:

  • To deliver therapeutic agents across the blood-brain barrier
  • To promote the formation of amyloid plaques
  • To block all neuronal communication
  • To increase neuroinflammation


Answer: To deliver therapeutic agents across the blood-brain barrier

22. Which of the following is NOT typically considered cargo of an exosome?

  • mRNA
  • microRNA
  • Proteins
  • The entire cell nucleus


Answer: The entire cell nucleus

23. The “parent cell” or “cell of origin” heavily influences the:

  • Size of the exosome exclusively
  • Contents and surface markers of the exosome
  • Color of the exosome
  • Method used to purify the exosome


Answer: Contents and surface markers of the exosome

24. A key quality control step in the production of therapeutic exosomes is:

  • Ensuring the preparation is free of contaminating proteins and other vesicles
  • Maximizing the amount of contamination to boost the immune response
  • Making sure the exosomes are all different sizes
  • Avoiding any characterization of the final product


Answer: Ensuring the preparation is free of contaminating proteins and other vesicles

25. A significant limitation of using ultracentrifugation for exosome isolation is:

  • It is very fast and requires no special equipment
  • It can co-precipitate contaminants and damage the vesicles
  • It only works for very small sample volumes
  • It is the most expensive method available


Answer: It can co-precipitate contaminants and damage the vesicles

26. Why are exosomes considered a promising vehicle for delivering siRNA?

  • They can protect the fragile siRNA from degradation in the bloodstream
  • The siRNA would be degraded inside the exosome
  • Exosomes cannot cross cell membranes
  • siRNA is not a therapeutic molecule


Answer: They can protect the fragile siRNA from degradation in the bloodstream

27. Exosomes are released from the cell through the fusion of:

  • The nucleus with the plasma membrane
  • The lysosome with the plasma membrane
  • The multivesicular body (MVB) with the plasma membrane
  • The mitochondrion with the plasma membrane


Answer: The multivesicular body (MVB) with the plasma membrane

28. Tetraspanins like CD63 are integral membrane proteins, making them useful markers for:

  • Verifying the presence of membrane-enclosed vesicles like exosomes
  • Identifying the RNA cargo inside an exosome
  • Measuring the concentration of soluble proteins
  • Confirming the absence of lipids


Answer: Verifying the presence of membrane-enclosed vesicles like exosomes

29. The therapeutic potential of exosomes derived from MSCs is thought to be mediated by their ability to:

  • Differentiate into new tissues
  • Transfer regenerative and anti-inflammatory molecules to recipient cells
  • Cause a strong pro-inflammatory response
  • Carry infectious agents


Answer: Transfer regenerative and anti-inflammatory molecules to recipient cells

30. Which technique is most suitable for visualizing the morphology of individual exosomes?

  • Standard light microscopy
  • Flow cytometry
  • Transmission Electron Microscopy (TEM)
  • PCR


Answer: Transmission Electron Microscopy (TEM)

31. A challenge in using exosomes as a “liquid biopsy” for early cancer detection is:

  • The low concentration of tumor-specific exosomes in the blood at early stages
  • The fact that tumors do not release exosomes
  • The extreme stability of exosomal biomarkers
  • The ease of distinguishing tumor exosomes from normal exosomes


Answer: The low concentration of tumor-specific exosomes in the blood at early stages

32. Electroporation is a technique that can be used to:

  • Isolate exosomes from urine
  • Create temporary pores in the exosome membrane to load therapeutic cargo
  • Measure the size of exosomes
  • Analyze the surface proteins of exosomes


Answer: Create temporary pores in the exosome membrane to load therapeutic cargo

33. Apoptotic bodies are typically ________ than exosomes.

  • Smaller and more uniform in size
  • The same size
  • Larger and more varied in size
  • Not considered a type of extracellular vesicle


Answer: Larger and more varied in size

34. The surface proteins on an exosome can determine its:

  • Target cell specificity
  • Internal RNA content
  • Lipid composition
  • Overall weight


Answer: Target cell specificity

35. A pharmacist counseling a patient about an exosome-based therapy would need to understand it is a type of:

  • Small molecule drug
  • Biologic therapy
  • Dietary supplement
  • Medical device


Answer: Biologic therapy

36. A current area of active research is engineering exosomes to express specific ________ on their surface for targeted drug delivery.

  • Lipids
  • Peptides or antibodies
  • Sugars
  • Nucleic acids


Answer: Peptides or antibodies

37. If an exosome-based drug is intended for intravenous administration, it must be:

  • Unpurified
  • Sterile and free of pyrogens
  • Loaded with bacteria
  • Kept at room temperature for several weeks


Answer: Sterile and free of pyrogens

38. The cargo of an exosome is primarily determined by the:

  • The type and physiological state of the parent cell
  • The type of fluid it is isolated from
  • The ultracentrifugation speed used for isolation
  • The temperature at which it is stored


Answer: The type and physiological state of the parent cell

39. One reason exosomes are being explored to treat brain disorders is their potential ability to cross the:

  • Blood-brain barrier
  • Cell wall
  • Nuclear membrane
  • Mitochondrial membrane


Answer: Blood-brain barrier

40. Size-exclusion chromatography (SEC) is an alternative purification method that separates exosomes based on:

  • Their surface charge
  • Their specific surface proteins
  • Their size
  • Their density


Answer: Their size

41. The information transferred by exosomes from one cell to another can influence the recipient cell’s:

  • Gene expression and behavior
  • Physical location in the body
  • Overall size
  • Color


Answer: Gene expression and behavior

42. Which of the following is a major bottleneck for the clinical translation of exosome therapies?

  • Lack of interest from the scientific community
  • The need for standardized and scalable manufacturing processes
  • The inability to load any cargo into them
  • The complete absence of any pre-clinical data


Answer: The need for standardized and scalable manufacturing processes

43. The “exosome industry” is currently characterized by:

  • A large number of FDA-approved therapeutic products
  • A focus on cosmetics and unproven therapies, alongside serious clinical research
  • A complete lack of commercial interest
  • A single company that controls all research


Answer: A focus on cosmetics and unproven therapies, alongside serious clinical research

44. What is the relationship between multivesicular bodies (MVBs) and exosomes?

  • Exosomes fuse to form MVBs
  • MVBs contain intraluminal vesicles that become exosomes upon release
  • They are two names for the same organelle
  • MVBs are responsible for degrading exosomes


Answer: MVBs contain intraluminal vesicles that become exosomes upon release

45. A key difference between exosomes and liposomes (a synthetic nanoparticle) is that exosomes have:

  • A simpler, more defined composition
  • A complex, biological membrane with embedded proteins
  • No lipid membrane
  • A much larger size


Answer: A complex, biological membrane with embedded proteins

46. The therapeutic effect of MSC-derived exosomes in tissue repair is thought to be an example of:

  • Direct differentiation of the exosomes into new cells
  • Paracrine signaling
  • Endocrine signaling
  • Apoptosis induction


Answer: Paracrine signaling

47. A Western blot analysis for the protein Alix would be used in exosome research as a:

  • Negative control marker
  • Positive cytosolic marker to confirm purity
  • Positive marker for exosome enrichment
  • Marker for nuclear contamination


Answer: Positive marker for exosome enrichment

48. The role of exosomes in spreading neurodegenerative proteins like tau and alpha-synuclein is a concern for disease ________.

  • a cure
  • prevention
  • progression
  • diagnosis


Answer: progression

49. If a researcher wants to deliver a drug to cancer cells using exosomes, a common strategy would be to harvest exosomes from:

  • The cancer cells themselves, as they may have a natural tendency to home back to their origin
  • Healthy liver cells
  • Mesenchymal stem cells
  • Bacterial cells


Answer: The cancer cells themselves, as they may have a natural tendency to home back to their origin

50. The future of exosome-based therapeutics heavily relies on overcoming challenges in:

  • Proving that cells can communicate with each other
  • Production, purification, and targeted delivery
  • Finding diseases to treat
  • Getting pharmacists interested in the topic


Answer: Production, purification, and targeted delivery

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