複選題

34. Which of the following statements about prokaryotic transcription is/are TRUE?
(A) The enzyme principally responsible for RNA synthesis in E. coli is a multisubunit enzyme.
(B) The first nucleotide incorporated into the RNA chain retains its 5'-triphosphate.
(C) The sigma (σ) subunit stays with the RNA Polymerase throughout synthesis.
(D) X Inverted-re peat sequences in the DA being transcribed can lead to termination
(E) The end ofthe new mRNA molecule in E. coli usually terminates in a string of A's.

複選題30.Here are two pieces of DNA, one with an adenine plus thymine content of 40%, and the other with a cytosine plus guanine content of 50%. If both are heated under the same experimental conditions, which of the following statement(s) about Tm of these DNAs is/are CORRECT? (A) The DNA with 40% adenine plus thymine will have the higher Tm. (B) The DNA with 50% adenine plus thymine will have the lower Tm. (C) The DNA with 50% cytosine plus guanine will have the higher Tm. (D) Their Tm's will be the same. (E) There's no way to predict for this information.

31.A class of mutations that results in multiple contiguous (side-by-side) amino acid changes in proteins is/are probably caused by which the following types of mutations? (A) recombinant (B) base analog (C) transversion (D) frameshift (E) transition

複選題32.Which of the following transcription factors is/are utilized by all threc eukaryotic RNA polymerases? (A) TFIID (B) TBP (C) DNA helicase (D) THIIIC (E) THIIF

複選題33. Which of following statements concerning RNA transcription is/are TRUE? (A) The DNA strands become separated during synthesis. (B) Synthesis of RNA is a very accurate process. (C) The template strand is read in the 3' -→＞ 5' direction. (D) Transcription requires the use of a primer. (E) DNA to RNA base pairing includes A to U and G to C.

35.Which of the following statements about the various RNA Polymerases in eukaryotes is/are FALSE? (A) Permanent RNAs, such as tRNA and rRNA use different RNA Polymerases. (B) The different RNA Polymerases share some subunits. (C) Eukaryotic RNA Polymerases are generally monomeric. (D) The RNA Polymerase for mRNA is designated RNA Pol Il. (E) Binding of TBP to the DNA is a key step in the activation of mRNA synthesis in eukaryotes.

複選題36. Which of the following statements is/are FALSE? (A) The majority of protein synthesis occurs in the cytoplasm. (B) Stop and his amino acids have unique codons. (C) All 64 of the codons code for an amino acid. (D) rRNA carries amino acids for the process of translation. (E) Wobble allows each codon to interact with more than one tRNA.

複選題37.Which of the following is/are FALSE about protein synthesis? (A) In bacteria, translation ofthe mRNA begins during the synthesis of the mRNA. (B) A Shine-Dalgarno Sequence is a sequence of nucleotides in an mRNA that functions to terminate translation. (C) Protein synthesis in prokaryotes always starts with a methionine residue. (D) Eukaryotic ribosomes recognize the Kozak sequence, surrounding the start codon in eukaryotes, to prevent false starts at inappropriate parts of the mRNA. (E) Both eukaryotic ribosomes and the protein factors used during the process of eukaryotic translation are very different from those in prokaryotic translation.

複選題38. Which of the following is/are TRUE about operons? (A) A single operon usually contains all the enzymes which are specific for the synthesis of a special biomolecule. (B) The effector for the Lac repressor protein is β-galactosidase. (C) Cyclic AMP affects transcription by phosphorylating a transcription factor. (D) Regarding regulation of the trp operon, the amino acid tryptophan acts as a corepressor. (E) Regarding the lactose utilization system in E. coli, a constitutive mutant is one in which the three enzymes are produced regardless of the presence or absence of lactose.

複選題39.Which of the following is/are TRUE of miRNA processing? (A) Drosha processes primary miRNA transcripts to precursor miRNAs. (B) RISC binds to pre-miRNA in the cytoplasm. (C) RNA helicase is necessary for unwinding the miRNA duplex. (D) Dicer completes the processing by cleaving the single-stranded form of the miRNA. (E) Precursor miRNAs are approximately 60-70 nucieotides long.

複選題40.Which of the following is/are a common nucleosomal protein covalent modification that affects gene expression? (A) Phosphorylation (B) Acetylation (C) Glycosylation (D) Methylation (E) Polyadenylation