NUR 631 Advanced Pathophysiology Exam with Questions and Answers

It covers key domains which include; Cellular and Molecular Biology, Immune and Inflammatory Responses, Neoplasia and Oncology and Integrative Pathophysiology. A 52-year-old patient with a history of chronic inflammation is found to have upregulated epidermal growth factor receptor (EGFR) signaling in biopsy samples. Which molecular event most directly activates Ras in the EGFR signaling cascade? a) Autophosphorylation of nuclear transcription factors b) Direct binding of EGF to Ras protein c) Recruitment of adaptor proteins such as Grb2 and SOS leading to GDP-GTP exchange on Ras d) Activation of mitochondrial cytochrome c release Correct Answer: c Rationale: In receptor tyrosine kinase signaling, ligand binding (e.g., EGF) induces receptor dimerization and autophosphorylation. This recruits adaptor proteins like Grb2 and SOS, which function as a guanine nucleotide exchange factor (GEF) that activates Ras by promoting GDP-GTP exchange. Ras activation is therefore indirect and depends on these adaptor-mediated interactions. A patient with severe ischemia undergoes cellular injury. Which event is most characteristic of the intrinsic (mitochondrial) pathway of apoptosis? a) Activation of Fas ligand on cytotoxic T cells b) Release of cytochrome c from mitochondria leading to apoptosome formation c) Increased synthesis of DNA repair enzymes in the nucleus d) Activation of membrane-bound receptor tyrosine kinases Correct Answer: b Rationale: The intrinsic apoptotic pathway is triggered by internal stress such as hypoxia or DNA damage. It involves mitochondrial outer membrane permeabilization and release of cytochrome c, which binds Apaf-1 to form the apoptosome and activates caspase-9, initiating the caspase cascade. A researcher studies gene silencing in cancer cells and finds hypermethylation of promoter regions. What is the most likely consequence of this epigenetic modification? a) Increased transcription of tumor suppressor genes b) Enhanced ribosomal RNA synthesis c) Increased histone acetylation and chromatin relaxation d) Decreased gene expression due to transcriptional repression Correct Answer: d Rationale: DNA methylation of promoter CpG islands typically leads to chromatin condensation and transcriptional repression. This mechanism is commonly associated with silencing of tumor suppressor genes in cancer, contributing to uncontrolled cell proliferation.