bioassayist Interview Questions and Answers

1. What is a bioassay?

   • Answer: A bioassay is a procedure for determining the concentration or potency of a substance by its effect on living matter.

2. Describe different types of bioassays.

   • Answer: There are many types, including cell-based assays (e.g., cytotoxicity assays, proliferation assays), animal models (e.g., LD50 determination), receptor binding assays, enzyme assays, and immunoassays (e.g., ELISA).

3. Explain the principle of a cytotoxicity assay.

   • Answer: Cytotoxicity assays measure the toxic effects of a substance on cells. This is often assessed by measuring cell viability, membrane integrity, or metabolic activity after exposure to the substance.

4. What is an EC50 and how is it determined?

   • Answer: EC50 is the half maximal effective concentration – the concentration of a substance that produces 50% of its maximal effect. It's determined graphically from dose-response curves, often using non-linear regression analysis.

5. What is an IC50 and how is it determined?

   • Answer: IC50 is the half maximal inhibitory concentration – the concentration of a substance that inhibits a biological process or response by 50%. It's determined similarly to EC50, using dose-response curves and non-linear regression.

6. Explain the importance of controls in a bioassay.

   • Answer: Controls (positive and negative) are crucial to validate the assay and ensure the results are reliable. Positive controls demonstrate the assay's ability to detect a positive response, while negative controls confirm the absence of a response in the absence of the tested substance.

7. What are the sources of error in bioassays?

   • Answer: Sources of error include variations in cell culture conditions, reagent quality, pipetting errors, assay variability, and the inherent biological variability of the experimental system.

8. How do you ensure the accuracy and precision of your bioassays?

   • Answer: By using proper controls, performing replicates, using standardized protocols, calibrating equipment regularly, and employing appropriate statistical analysis.

9. Describe your experience with different cell culture techniques.

   • Answer: [Candidate should detail their experience with cell passaging, seeding, media preparation, sterility techniques, and specific cell types they've worked with.]

10. What software or tools do you use for data analysis in bioassays?

    • Answer: [Candidate should list software like GraphPad Prism, Excel, specialized statistical packages, and describe their proficiency in data analysis techniques like curve fitting and statistical tests.]

11. Explain your understanding of GLP (Good Laboratory Practices).

    • Answer: GLP is a quality system covering the organizational process and the conditions under which laboratory studies are planned, performed, monitored, recorded, archived, and reported.

12. What safety precautions do you take when working with biological samples?

    • Answer: Proper PPE (personal protective equipment), sterile techniques, biosafety cabinets, waste disposal protocols, and adherence to relevant safety regulations.

13. How do you troubleshoot problems encountered during a bioassay?

    • Answer: Systematic approach: Review the protocol, check reagents, examine cell health, consider possible contamination, analyze data for outliers, and consult relevant literature.

14. What are the ethical considerations in conducting bioassays?

    • Answer: Minimizing animal suffering (if using animal models), adherence to ethical guidelines for human subjects research, responsible use of resources, data integrity, and accurate reporting.

15. Describe your experience with ELISA.

    • Answer: [Candidate should detail their experience with different ELISA types (e.g., direct, indirect, sandwich), including protocol execution, data interpretation, and troubleshooting.]

16. How would you validate a new bioassay?

    • Answer: Through assessing parameters like accuracy, precision, sensitivity, specificity, linearity, and range, often involving comparison with established methods.

17. Explain your understanding of different types of assay formats (e.g., high-throughput screening).

    • Answer: [Candidate should discuss different formats, including their advantages and limitations. High-throughput screening involves automation to screen large numbers of compounds quickly.]

18. How do you document your work in a bioassay?

    • Answer: Detailed lab notebooks, electronic data management systems, following SOPs (Standard Operating Procedures), and generating comprehensive reports.

19. What are your strengths as a bioassayist?

    • Answer: [Candidate should highlight relevant skills like meticulousness, attention to detail, problem-solving abilities, data analysis skills, understanding of experimental design, and teamwork.

20. What are your weaknesses as a bioassayist?

    • Answer: [Candidate should choose a genuine weakness and explain how they are working to improve it. Avoid generic answers.]

21. Why are you interested in this position?

    • Answer: [Candidate should connect their skills and interests to the specific job requirements and company goals.]

22. Where do you see yourself in 5 years?

    • Answer: [Candidate should demonstrate career progression goals aligned with the position and company.]

23. What is your salary expectation?

    • Answer: [Candidate should research industry standards and provide a realistic salary range.]

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