31. The functional activity of proteins can be modulated by protein modification. Which description is not true?
(A) Mass spectrometry is a tool to identify protein modification.
(B) Protein phosphorylation occurs at the residues of Ser, Thr, and Tyr.
(C) Protein methylation occurs at the residues of Leu and Arg.
(D) Histone acetylation results in gene activation.
(E) Histone methylation would activate or repress gene expression.

27. Which of the following general statement about a G protein-coupled receptor is true? 　1. It contains twelve transmembrane domains. 　2. It is organized with the N-terminus on the cytoplasmic face of the membrane. 　3. It is organized with the C-terminus on the cytoplasmic face of the membrane. 　4. It is found only in eukaryotes (A) Only 3 is correct (B) 2, 4 are correct. (C) 3, 4 are correct. (D) 1, 2 are correct. (E) 1, 3, 4 are correct.

28. Which one of the following statements about mitochondrial DNA is incorrect? (A) Products of mitochondrial genes are not exported to cytosol (B) All the mitochondria of a developing embryo are derived from the mother's egg (C) Mitochondrial genetic codes differ from the standard nuclear code (D) Mitochondria contain one non-histone mitochondria DNA molecule (E) Mutations in mitochondrial DNA would cause genetic diseases.

29. Which E3 ligase is involved in sister chromatid segregation during mitosis? (A) APC/C (B) RNF8 (C) RNF168 (D) BRCA1 (E) Cul3-KLHL20

30. Which one is NOT the difference between microtubules and microfilaments? (A) Microfilament is made of G-actin. (B) Microtubule is made of a/ẞ tubulin (C) Dynein is a motor protein in microfilaments. (D) Microtubules have branching. (E) Microtubules need GTP but microfilaments need ATP for their formation.

32. Binding of hormone to a receptor tyrosine kinase causes all of the following except: (A) dimerization of the receptor. (B) autophosphorylation of the receptor. (C) activation of Ras through an interaction with GRB2 and Sos. (D) hydrolysis of GTP bound to Ras. (E) All of the above are incorrect.

33. Predict the consequences of a temperature sensitive mutation in which the phosphorylation of the b-catenin protein is blocked. Above the permissive temperature, (A) b-catenin levels will increase and b-catenin will be constitutively active. (B) b-catenin levels will increase and b-catenin will be inactive. (C) b-catenin levels will decrease and cells will be inactive. (D) b-catenin will remain decrease and cells will be more sensitive to Wnt signaling (E) b-catenin will remain constant but cells will be unresponsive to Wnt signaling.

34. Fully differentiated mouse fibroblasts can be reprogrammed or induced to form pluripotent stem cells when transfected with retroviral vectors expressing: 　 1. KLF4.2. c-MYC. 3. SOX2. 4. Ngn1 5. Oct4 (A) 1, 2, 3, 5 (B)1, 2, 3, 4 (C) 1, 2, 4, 5 (D) 1, 3, 4, 5 (Ε) 2, 3, 4, 5

35. Which one is NOT the marker of Epithelial-mesenchymal transition? (A) N-cadherin (B) E-cadherin (C) vitronectin (D) integrin (E) Zebl

36. Which statement listed below concerning general molecular biology techniques is correct? 1. Run-on transcription determines the translational rate. 　 2. Primer extension determines the start of transcription. 　 3. Southern blot determines if a probe is complementary to a DNA target. 　 4. Northern blot determines the size and abundance of a RNA. 　 5. Gel mobility shift assay determines whether a protein binds DNA. (A) 1, 2, 3, 4 are correct. (B) 1, 3, 4, 5 are correct. (C) 2, 3, 4, 5 are correct. (D) 1, 3, 4, 5 are correct. (E) All of above are correct.

37. What method can be used to functionally inactivate a gene without altering its sequence? 1. gene knockout 　 2. RNA interference 　 3. dominant negative mutation 　 4. CRISPR/Cas9 system (A) 1 and 2 are correct. (B) 2 and 3 are correct. (C) 2 and 4 are correct. (D) 1, 2 and 4 are correct. (E) All of above are correct.