Mcqs In Cell Injury And Histochemistry

Prof.Dr. Ashour Abdelsalam Medical Research Institute Tumor Cell Biology Dept.

Date: 03/03/2009

Master Degree Examination (Histochemistry of Cell Injury) A) Choose the right answer (s): 1. Chemical agents cause sever damage by a. changing membrane permeability b. altering integrity of an enzyme or co-factor c. modifying osmotic homeostasis d. all of the above Correct: d 2. Infectious agents cause tissue damage through a. release enzymes that degrade tissue component b. release toxins that kill cells c. enter host cells and cause direct cell death d. all of the above Correct: d 3. Poisoning of aerobic respiration with cyanide results a. in diminished activity of sodium / potassium - ATPase b. in increased activity of magnesium - ATPase c. in increased activity of calcium - ATPase d. none of the above Correct: a 4. Increased cytosolic calcium ion causes a. activation of phospholipases which promot membrane damage b. catabolizing structural and membranous proteins c. fragmentation of genetic material by endonucleases d. all of the above Correct: d 5. Ischemia injures tissue faster than does hypoxia due to a. diminished blood flow b. compromised delivery of substances for glycolysis c. blocked anaerobic energy generation d. all of the above Correct: d 6. Reduced PAS stain indicates a. increased anaerobic glycolysis b. rapid depletion of glycogen stores c. accumulation of lactic acid d. generation of ATP from glycogen Correct: d 7. During normal respiration, molecular oxygen is reduced in mitochondria to generate water and superoxide radicals that can be histochemically demonstrated by a. superoxide dismutase

b. glutathione peroxidase c. catalase d. all of the above Correct: d 8. The following reactions are relevant to cell injury mediated by free radicals a. lipid peroxidation b. DNA fragmentation c. Cross-linking of proteins d. Direct polypeptide fragmentation Correct: d 9. Ubiquitin is a 76-amino acid cytosolic peptide and is responsible for a. degradation of many cytosolic proteins only b. degradation of many nuclear proteins only c. both of them d. none of them Correct: c 10. The P-450 mixed function oxidases system a. metabolizes the drugs in hepatocytes b. increases solubility of toxins c. facilitates excretion of toxins d. all of the above Correct: d 11. Clear vacuoles within liver tissue indicates a. fatty accumulation if you use PAS technique b. glycogen accumulation if you use sudan - black technique c. fat droplets if you use Oil red – O technique d. water accumulation if you use red – violet technique Correct: c 12. Lipofuscin a. is the wear- and -tear pigments b. represents complexes of lipid and protein that derived from free radicalcatalyzed peroxidation of polyunsaturated lipids c. is perinuclear brownish yellow granules that indicate function of age or atrophy d. is not injurious to cells but is a marker of past free radical injury e. all of the above Correct: e 13. Melanin a. is an endogenous pigment b. is formed by melanocytes via tyrosinase c. indicates harmful ultraviolet radiation d. all of the above Correct: d

14. Hemosiderin a. is a hemoglobin-derived pigment b. accumulates in tissues when there is excess of iron c. is a golden yellow granules normally found in small amount in liver, spleen and bone marrow d. can be identified histochemically by Prussian blue technique e. all of the above Correct: e 15. Dystrophic calcification a. is encountered in areas of necrosis b. represents evidence of previous cell injury c. appears as intracellular and/or extracellular basophilic deposits d. all of the above Correct: d 16. Irreversible cell injury can be histochemically identified by a. extensive damage of membranes b. swelling of lysosomes c. vacuolization of mitochondria d. increased activity of catabolized enzymes e. all of the above Correct: e 17. In irreversible cell injury, there is a. loss of proteins and essential coenzymes b. loss of ribonucleic acid c. leakage of lysosomal enzymes d. further depletion of intracellular ATPase e. all of the above Correct: e 18. Dead cells show increased eosinophilia that attributed to a. increased binding of eosin to denatured intracytoplasmic proteins b. in part loss of basophilia c. excess of glycogen particles d. loss of RNA in cytoplasm Correct: a & b 19. Apoptosis usually involves a. single cells b. cluster of cells c. condensed nuclear chromatin d. peripheral aggregation of chromatin e. all of the above Correct: e 20. Formation of pores within inner mitochondrial membrane results in a. decreased ATP production b. mitochondrial swelling c. increased permeability of outer mitochondrial membrane d. none of the above

Correct: a & b 21. Increased permeability of outer mitochondrial membrane results in a. releasing cytochrome C into cytosol b. binding cytochrome C with pro-apoptotic factor c. triggering execution caspases' activation d. all of the above Correct: d 22. B Cl2 a. is found in mitochondrial membranes b. suppresses apoptosis c. prevents increased mitochondrial permeability d. prevents caspases' activation e. all of the above Correct: e 23. Caspases a. are oxidative enzymes with cystein active sites b. are proteases that cleave proteins after aspartic acid residues c. their over expression results in cellular apoptosis d. their over expression results in cellular necrosis Correct: b & c 24. In apoptosis, there is a. DNA breakdown into 200 base pair fragments b. release of calcium and magnesium dependent endonucleases c. release of calcium and magnesium dependent ATPase d. all of the above Correct a & b 25. The following cell injury is encountered by age a. reduction of mitochondrial oxidative phosphorylation b. pleomorphic vacuolated mitochondria c. reduced synthesis of structural, enzymatic and receptor proteins d. diminished ER and distorted Golgi apparatus e. steady accumulation of lipofuscin pigments Correct: a, b & c 26. In cell injury, form cell systems are particularly vulnerable a. cell membrane integrity b. ATP generation c. protein synthesis d. integrity of genetic apparatus e. all of the above Correct: e

B) Fill in the spaces 1. Heat shock proteins that play an important roles in normal intracellular proteins are called housekeeping proteins 2. The ubiquitin-proteosome pathway is responsible for the degradation of many cytosolic and nuclear proteins 3. Mallory body, an eosinophilic intracytoplasmic inclusion in hepatocytes , indicates alcoholic liver. 4. Excessive intracellular deposits of glycogen are associated with abnormalities in the metabolism of glucose or glycogen 5. Pigments are colored substances that are exogenous or endogenous materials 6. Lipofuscin represents complexes of lipid and proteins 7. Lipofuscin is derived from the radical catabolized peroxidation of polyunsaturated lipids of subcellular proteins 8. Lipofuscin is a marker of past free radical injury 9. Dystrofic calcification is the deposition of calcium in dead tissues while metastatic calcification is deposition of calcium in normal tissues 10. Calcium accumulates by its affinity for membrane phospholipids while phosphorous accumulates as a result of the action of membrane-bound phosphatases 11. Mitochondria have the ability to regulate intracellular calcium 12. Early ultrastructure markers of irreversible injury is the accumulation of calciumrich deposits in mitochondrial matrix 13. Activation of endogenous phospholipids in ischemic liver tissues is associated with decrease in membrane phospholysis 14. Activation of proteases by increased intracellular calcium may result in damage to cytoskeleton 15. Collagen bundles serve to repair injury forming what is known as scar tissues 16. In injury with pathogens or their toxins, plasma cells produce specific proteins called antigens 17. In injury with local damage, basophils release their granules in the site of injury and histamine causes vasodilatation but heparin prevents clotting of blood in intact vessels Key words: MCQs, Histochemistry, Cell injury,