46. You are working with a gene associated with an essential pathway that is necessary at two time points in an organism's lifetime. With regard to gene regulation, you would expect the gene to be
(A) constitutive.
(B) associated with response to distinct events through induction and repression signals.
(C) induced by particular signals.
(D) repressed by particular signals.

42. Of the following steps associated with translation, which does not involve hydrolysis of GTP? (A) Aminoacylation oftRNA (B) Formation of the initiation complex (C) Binding of the aminoacyl tRNA to the codon at the A site (D) Translocation of the ribosome

43. In eukaryotes, the 3' end of the mRNA is important in the initiation of translation because (A) it contains Kozak sequences that aid in initiation. (B) translation occurs in the 3' to 5' direction. (C) elF4A is attached to the 3' cnd and removes any sccondary structure that might prevent translation. (D) the 3' poly( A ) tail and PABP bind initiation factor elF4G, stabilizing the 5' end of the mRNA.

44. Which of the following statements is not true concerning peptidyI transferase? (A) It is a ribozyme having catalytic activity. (B) It catalyzes peptide bond formation. (C) It moves the ribosome, so translation continues. (D) It is associated with the large subunit of ribosomes.

45. Gene knockdown via RNAi relies on the ability of eukaryotic cells to (A) degrade target mRNAs that are complementary to introduced dsRNA. (B) induce microRNA expression under particular conditions. (C) preferentially degrade mutated mRNAs. (D) inhibit transcription of sets of genes based on the presence of distal control elements.

47. The amount of a protein in a cell is regulated by the rate of (A) transcription of its gene. (B) translation of its mRNA. (C) degradation of the protein. (D) All of the above

48. Release of RNA polymerase II to initiate transcription appears to be the direct result of the (A) binding of TAFs to the polymerase. (B)unwinding of the DNA by helicases. (C) phosphorylation of RNA polymerase by a protein kinase. (D) removal of the nucleosome occupying the promoter site.

複選題49. What are some diseases caused by vitamin deficiencies that affect the pyruvate dehydrogenase complex and a-ketoglutarate dehydrogenase complex? (A) vit. B1– cheilosis, angular stomatitis (B) niacin –pellagra (C) pantothenic acid – fatigue, insomnia, depression, irritability (D) riboflavin – Wernicke-Korsakoff syndrome, beriberi

複選題50. In the case of a patient with liver cirthosis who also indulges in alcohol consumption, which of the following physiological states might be observed? Which of the following statements could be correct? (A) The first step in alcohol metabolism requires pyruvate decarboxylase, and patients may benefit from additional thiamine supplementation. (B) The thiazole ring of TPP serves as the functional moiety of the coenzyme, facilitating the binding and transfer of active aldehyde. These steps do not require ATP. (C) Alcohol dehydrogenase is present in animal tissues, even though ethanol is not a primary metabolic product in animal cells. (D) Acetaldehyde and its metabolite do not pose toxicity to animals.

複選題51. Which of the following statements about diseases associated with mitochondrial gene mutations and affected electron transport chain complexes are incorrect? (A) Leigh Syndrome causes difficulty swallowing and decreased motor abilities→only complex I (B) Hypertrophic cardiomyopathy results in cardiac enlargement and degeneration→ only complex III and IV (C) Pearson Syndrome leads to sideroblastic anemia → only complex I and IV (D) Kearns-Sayre syndrome causes ophthalmoplegia and ragged red fibers →only complex I and IV and IV

複選題52. Among the following carbohydrates, glucose transport proteins, and specific tissue cell functions, which statement is/are incorrect? (A) GLUT1 - galactose- kidney cells and intestinal epithelial cells (B) GLUT2 - fructose - intestinal and renal tubular basolateral epithelial cells, liver cells (C) GLUT4 - glucose - brain, placenta, testes (D) GLUT7 - fructose - membrane of endoplasmic reticulum in liver cells