複選題

30.CRISPR is a famous genome-editing tool. Which of following statement is (are) TRUE:
(A) CRISPR is discovered as a bacterial immune system
(B) There are multiple types of CRISPR
(C) Two major components that introduced into mammalian cell for genome editing are cas-9 protein and guide DNA
(D) Creating gene deletion using CRISPR rely on the mistake of DNA repairing system in the host cell
(E) The recognition sequence for the cas-9 crispr system is the three nucleotide PAM sequence

26. Which of the following amino acid residues has polar side chain: (A) Arginine (B) Asparagine (C) Phenylalanine (D) Lysine (E) Tryptophan

複選題27. Which of following statement is (are) TRUE: (A) Hydrophobic means it is water-like (B) Nucleic acid dissolved in water is because it is a negatively charged molecule. (C) Sodium acetate solution can not neutralize the charge of nucleic acid (D) The principle of ethanol precipitation is based on nucleic acid is not able to dissolved in ethanol (E) Most denatured proteins are water soluble

複選題28. What of the following statements is (are) TRUE: (A) Regardless Prokaryote or Eukaryote, ribosome is responsible for protein synthesis (B) An actively translated mRNA often has one ribosome on the mRNA (C) Eukaryote mRNA often forms in a circle to facilitate translation (D) There is one three-nucleotide sequence corresponding to stop codon (E) E site in ribosome responsible for polypeptide elongation

複選題29. What of the following statements is (are) TRUE: (A) Since there are 20 amino acids, there are 20 different tRNAs in the cell. (B) Despite the sequence differences within all tRNAs, all tRNAs have very similar tertiary structure (C) Only aminoacyl tRNA can be used in ribosome mediated polypeptide elongation. (D) No enzyme is required for tRNA amino acid addition (E) Upon tRNA is transcribed, tRNA can be used to incorporate amino acid

31.There are 45 different kinds tRNA (anticodons) available to serve as amino acid carriers, but there are 64 mRNA codons. Why aren't the tRNA anticodons and mRNA codons equal in number? (A) The reason is that some tRNA anticodons can misread some of the mRNA codons, which creates a "wobble" in the tRNA anticodons that can be repaired by RNA repair enzymes. (B) The reason is that the third base pair on the mRNA codon allows some flexibility (wobble)； thus, some tRNA anticodons can recognize more than one mRNA codon. (C) The reason is that the third base pair on the tRNA allows some flexibility (wobble)； thus, some tRNA anticodons can recognize more than one mRNA codon. (D) The reason is that the tRNA has the flexibility to choose which mRNA codons are necessary for building the polypeptide chain. (E) This broader recognition occurs because of the nonstandard pairing between bases in the wobble position corresponding to the 3' base in the mRNA and the complementary 5′ base in the tRNA anticodon.

複選題32. Which of the following describe the general mechanism of DNA synthesis is (are) TRUE? (A) One strand is made 5' → 3', while the other strand is made 3' → 5' in short discontinuous segments. (B) The strands become separated during synthesis. (C) Synthesis occurs in one direction from the starting site of synthesis. (D) Synthesis of DNA is a very accurate process. (E) DNA is replicated by a semi-conservative mechanism.

33.A mutation that changes the recognition sequence for the restriction enzyme EcoRI from GAATTC to GATTTC is an example of a (A) restriction fragment length polymorphism (RFLP). (B) single nucleotide polymorphism (SNP). (C) simple sequence repeat (SSR). (D) genetic heterogeneity (E) none of the above

複選題34. Which of the following statement(s) about intracellular second messengers is (are) TRUE? (A) It is a substance that brings about a desired effect in a cell as a result of a hormone binding to its receptor on the cell surface. (B) It is a hormone that affects the DNA of the target cell. (C) It is a specialized form of mRNA. (D) Cyclic ATP can act as secondary messengers. (E) Ca2+ can function as a secondary messenger by controlling the flow of Ca2+ into the cells.

複選題35. Which of the following statement(s) about heterochromatin is (are) CORRECT? (A) It is a region of condensed chromatin. (B) It is a region without DNA replication. (C) It is often simple sequence DNA. (D) It is a dark-staining area of a chromosome. (E) It is usually transcriptionally active.

複選題36. The three dimensional structure of nucleic acids can include: (A) Supercoiling (B) Base stacking (C) beads on a string (D) Circular molecules (E) Hairpin loops.