Biomedical Sciences Flashcards
7 cards from real STP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Biomedical Sciences flashcards as text
Which type of cell junction prevents the passage of molecules between adjacent epithelial cells?
Answer: Tight junction
Tight junctions (zonula occludens) form a seal between epithelial cells, preventing paracellular passage of molecules.
In Western blotting, what is the purpose of the blocking step?
Answer: To prevent non-specific antibody binding
Blocking with BSA or milk saturates non-specific binding sites on the membrane to reduce background signal.
Which complement pathway is activated by mannose-binding lectin (MBL)?
Answer: Lectin pathway
MBL recognizes carbohydrate patterns on pathogens and activates complement via the lectin (MBL) pathway.
A patient has a prolonged aPTT but normal PT. Which factor is most likely deficient?
Answer: Factor VIII
Factor VIII deficiency (hemophilia A) prolongs aPTT (intrinsic pathway) while PT (extrinsic pathway) remains normal.
Which microscopy technique is best suited for imaging live, unstained cells without phototoxicity concerns?
Answer: Phase contrast microscopy
Phase contrast microscopy exploits differences in refractive index and requires no staining or fixation, making it ideal for live cells.
What is the role of ubiquitin in cellular protein quality control?
Answer: It tags proteins for degradation by the proteasome
Polyubiquitination of misfolded or damaged proteins marks them for recognition and degradation by the 26S proteasome.
Which cytokine is primarily responsible for inducing acute-phase protein synthesis in the liver during infection?
Answer: IL-6
IL-6 signals hepatocytes to upregulate acute-phase proteins such as C-reactive protein and fibrinogen during systemic inflammation.