pilot examination Biochemistry

naxazixi's version from 2015-05-29 06:25


Question Answer
A1. Which of the following describes the movement of glycine molecules in an electric field at a pH of 6.06 (the isoelectric pH for glycine)? The glycine molecules willnot move.


Question Answer
A2. Which of the following pairs of amino acids is expected to be found on the interior of a globular protein?Leucine and valine
A3. Which of the following is an allosteric effector of an enzymatic reaction? Substance affecting enzymatic activity by binding to non-active sites
A4 . Zinc is an essential component of which of the following?Carbonic anhydrase
A5. Which of the following describes a major effect of sickle cell anemia? Decreased solubility of the deoxy form of hemoglobin


Question Answer
A6. The unique amino acid composition of collagen is reflected in the high content ofglycine, proline, and hydroxyproline.
A7. Which of the following is MOST likely to promote depolymerization of extracellular matrix?Hyaluronidase
A8. Which of the following vitamins is essential for the normal elaboration and maintenance of bone matrix, cartilage, and dentin? Ascorbic acid
A9. Which of the following statements BEST describes hydroxyapatite in enamel?Has a higher solubility than fluorapatite
Question Answer
A10. What are predominant linkages in glycogen between glucose units?Alpha-1,4.
A11. Glucose can be made from each of the following substancesLactate , Glycerol , Pyruvate Fructose (Which one is this EXCEPTION ?(Acetyl CoA)
A12. Which of the following is the pathway that results in the formation of glucose in the liver from lactate produced in muscle?Cori cycle
A13. Which of the following mechanisms operates in liver cells to regulate breakdown of glycogen?Phosphorylation of phosphorylase b to phosphorylase a
CA14. Glucose-6-phosphatase is found associated with which of the following organs ?Kidneys and liver


formula para transcripico esta atendo a que te pinden y que te dan asume si no te dan direccion que es de 5 a 3 lo q te dan ok
                                                                                                        linea uno: codin 5 a 3
                                                                                              linea dos templete 3 a 5
                                                                                                  linea tres mRNA 5 a 3


Question Answer
comprises most of RNARIbosomal RNA 2 tRNA 3 mRNA
backbone of DNA is consist of deoxyribososes like by phospodiester bridges of bonds hydrophilic , high polar , and constan thoughout the molecues ,
DNA pairin isA-T and G-C complementary base
RNA paring isU-A and the no thyamine because T se cambia por -U
A- T promotes helix stabilizaton of DNA only not inRNA
HIV virus have the unique ability toproduce DNA form mRNA
What enzyme use HIV virus to produce DNA form mRNAreverse transcriptase also used for genetic engineering
genetic recombination depens on two enzymesRestriction ENDONUCLEASE and DNA ligase
A15. Which of the following base pairs promotes helix stabilization in DNA but does NOT do so in RNA?A-T. (A-U in RNA promote helix stabilizaiton )
A16. If the anticodon on transfer-RNA is 5’ACG3’, then which of the following is its corresponding codon on messenger-RNA 5’ CGU 3’
A17. DNA that is complementary to mRNA can be made using which of the following? Reverse transcriptase
A18. Which of the following represents the consequence of the fact that DNA strands are complementary? Separated strands are able to reassociate
A19. Which of the following enzymes seals nicks in DNA? Ligase
A20. Which of the following BEST describes the major function of histones? Stabilize DNA in a compact form.
A21. Which of the following BEST describes restriction enzymes?Site-specific endonucleases
A22. Which of the following types of blotting can be used to identify DNA restriction fragments?Southern (DNA va al sur)
Which of the following types of blotting can be used to identify RNA restriction fragments ? Northern blotting RNA VA AL NORTE DNA VA AL SUR
Western blotting is used to detect a particular protein in a mixture NOT DNA OR RNA la gente del west come mucha proteina
A23. Which of the following enzymes synthesizes polynucleotide chains from nucleotides and does NOT require a primer chain?RNA polymerase
A24. Which of the following is produced when a mutation occurs in an enzyme controlling a signal pathway involved in cell growth processes? Oncogene


Question Answer
A25. The first step in the pathway for fatty acid synthesis is catalyzed by an allosteric enzyme which is the principal regulator of the pathway. This enzyme isacetyl CoA carboxylase.
A26. Each of the following is expected to be active during fatty acid biosynthesis ( EXCEPT Beta oxidation ). ?Tricarboxylic acid cycle , Pyruvate dehydrogenase ,. Amino acid catabolism Glycolysis
A27. Which of the following is a ketone body?Acetoacetate
A28. Bile salts are sodium salts of bile acid that are conjugated with ?taurine and glycine
Question Answer
A29. Facilitated diffusion DIFFERS from active transport in that net transport by facilitated diffusionrequires a concentration gradient.
A30. The cell membrane is LEAST permeable to which of the following substances?Sodium
A31. Active transport systems generally involve specific binding molecules that are classified as a protein.
A32. Which of the following provides the immediate energy source for the transport of glucose into intestinal epithelial cells?Na+ gradient across the luminal membrena
Question Answer
A33. Which of the following substances is the predominant source of ATP at MODERATE levels (for greater than 60 minutes) of activity? Fatty acids
A34. The catabolism of which of the following results in no energy production in the form of ATP?nucleotide
A35. Which of the following directly catalyzes urea formation in a cell? Arginnasa
A36. Which main product of protein nitrogen metabolism is found in human urine? : Urea
A37. Which of the following compound is a precursor of the pigments of the skin, hair, and eyes? : Tyrosine


Question Answer
A38. Which of the following promotes the release of bile from the gallbladder?Cholecystokinin
A39. Hormones that exert their effects through the activation of second messengers are usually water soluble peptide/protein hormones.
A40. Which of the following hormones exerts the LEAST effect on calcium metabolism of bone tissues? :Norepinephrine
Question Answer
A41. The biologically active conformation of trimeric G-proteins requires the alpha-subunit to bind GTP.
Question Answer
A42. Each of the following coenzymes is a component of the pyruvate dehydrogenase complex (EXCEPT Biotin).NAD , Coenzyme A , Thiamine pyrophosphate


Question Answer
A43. Which of the following coenzymes is required for the synthesis of pyrimidines, such as thymine?Folic acid


Testlet 1.
A 23-year-old female present with complaints of difficulty in opening her mouth and a low-grade fever of several days’ duration. The medical history indicates a recent positive PPD skin test, and the patient is taking rifampin (Rifadin®). The extra-oral exam shows diffuse swelling at the angle of the right mandible and lacteral neck. Oral exam shows gingival swelling and erythema around partially erupted Tooth #32.


A44. Rifampin (Rifadin®) is effective in treating active tuberculosis because it targets which of the following pathways? D. Transcription


Testlet 2.
A 15-year-old male presents for emergency care. He is non-compliant with his type I diabetes regimen, and he suffered a fall while having an insulin reaction. He struck his chin and lacerated his tongue. Upon opening, his mandible deviates to the left. A panoramic radiograph reveals a fracture of the left condylar neck.


Question Answer
A45. Before examining this patient, the dentist notes that the standard medical emergency kit contains an ampule of glucagon. For which of the following reasons would glucagon be used? Promotes glycogenolysis in the hypoglycemic patient.
A46. The patient’s “insulin reaction” represented a sudden fall in blood glucose because he had taken his normal insulin dose but did not eat breakfast. Each of the following is a clinical manifestation of hypoglycemia EXCEPT one. ( Which one is this EXCEPTION Coma)? Dizziness ,Confusion , Convulsion , Hyperventilation
A47. Which of the following glucose transporters was responsible for the patient’s “insulin reaction”? GLUT-4


Testlet 3.
An 80-year-old female with a history of cardiovascular disease presents with a complaint of pain under her complete dentures when biting. She has worn them for 15 years, but seldom removes or cleans them. Removal of the dentures reveals diffuse erythema of underlying mucosal tissue. Bone resorption is noted from detectable reduction in height of the alveolar ridges due to the ill-fitting denture.


Question Answer
A48. The bone resorption seen in elderly patients with low dietary calcium is enhanced by which of the following hormones?Parathyroid hormone
A49. Administration of a local anesthetic with epinephrine will MOST likely produce which of the following cardiovascular effects?Increased heart rate