39.The tryptophan operon of E.coli is repressed by tryptophan added to the growth medium. The tryptophan repr
(A) binds to RNA polymerase when tryptophan is present.
(B) binds to the trp operator in the absence of tryptophan.
(C) binds to the trp operator in the presence of tryptophan.
(D) is a DNA sequence.
(E) is an attenuator.

35. To study the function of the essential cyclin genes in yeast, researchers constructed a shuttlc vector in which a copy of the cyclin gene was ligated to the GAL1 promoter. The vector was then introduced into haploid yeast cells in which all copies of the cyclin genes had been disrupted. Following introduction of the vector, you would expect that (A) the yeast cells would grow on both glucose and galactose media. (B) the yeast cells would grow on glucose but not galactose medium. (C) the yeast cells would grow on galactose but not glucose medium. (D) on transfer to either glucose or galactose medium, the vector-carrying cells would eventually stop growing because of insufficient cyclinexpression. (E) none of the above

36. In intestinal epithelial cells, the different plasma membrane domains are separated from each other by special barriers. Which of the following statements is false? (1) These barriers are set up by nanoscale lipid raft domains.(2) Proteins normally cannot pass through these barriers, whereas any membrane lipid can do so freely. (3)The  asymmetric distribution of membrane proteins resulting from these barriers is functiona(4) These barriers are a result of proteins of the apical surface forming a large aggregate that excludes proteins of the other domains. (A) (I), (2) and (3) (B) (2), (3) and (4) (C) (1) and (4) (D) (1), (2) and (4) (E) All of the above

37.Whis of the following lipids do you expect to be a canonical scramblase substrate in the plasn (A) Galactocerebroside (B) Phosphatidylethanolamine (C) Glycosylphosphatidylinositol (D) Cholesterol (E) Ganglioside GMI

38."Housekeeping genes" in bacteria are commonly expressed constitutively, but not all of these genes are expr (the same number of molecules per cell). The primary mechanism responsible for variations in the lev enzymes from different genes is that: (A) all constitutive enzymnes are synthesized at the same rate, but are not degraded equally. (B) their promoters have different affinities for RNA polymerase holoenzyme. (C) some constitutively expressed genes are more inducible than others. (D) some constitutively expressed genes are more repressible than others. (E) the same number of mRNA copies are made from each gene but are translated at different rates.

40. All are characteristics of transposons except: (A) segments of DNA moved non-enzymatically in the genome. (B) unstable location within genome. (C) range in size from hundreds of bps to 8 kbp. (D) the smallest transposons are called insertion sequences. (E) a major force in evolution.

複選題1.Development of mRNA vaccines helps against COVID-19. Dr. Kariko and Weissman won the 2023 Nobel Prize in Physiology or Medicine. Which discoveries described below are their main contribution? (A) DNA base modification. (B) RNA base modification. (C) Base modification leads to increased inflammatory response. (D) Base modification leads to reduced inflammatory response. (E) The mRNA vaccines with base modification increased protein production.

複選題2. Which functional groups of the common structure of amino acids are used to form peptide bonds? (A) Amino group (B) Side chain (C) H atom (D) Carboxyl group (E) OH

複選題3. Which descriptions of the differences between eukaryotic and prokaryotic transcription are wrong? (A) Eukaryotic transcription occurs in the nucleus. (B) The 28S, 18S, 5.8S, and 5S rRNAs of eukaryotes are formed from one primary transcript. (C) There is no definite phase for prokaryotic transcription occurrence. (D) The eukaryotic transcriptional unit has one or more genes (polycistronic). (E) A single RNA polymerase of prokaryotes synthesizes all three types of RNA (mRNA, tRNA, and rRNA).

複選題4.How do eukaryotes generate various isoforms of RNA transcript from one gene? (A) Selective splicing (B) Alternative 5' donor site (C) Alternative 3' acceptor site (D) Alternative polyadenylation site (E) Different RNA polymerases

複選題5. Which descriptions of ribozyme are right? (A) Ribozyme is a protein. (B) Ribozyme is an RNA. (C) The substrate of ribozyme is proteins. (D) The substrate of ribozyme is DNA. (E) The substrate of ribozyme is RNA.