複選題

24. Which of the following statements about poliovirus are correct?
(A) Poliovirus directly degrades host mRNA.
(B) Poliovirus protease degrades eIF4G.
(C) Poliovirus RNA harbors a 5' cap structure.
(D) The IRES element is present in most mRNAs.
(E) eIF4E facilitates the translation of picornavirus mRNAs.

20. Which of the following statements about alternative splicing is correct? (A) Alternative splicing occurs only in protein-coding genes and excludes noncoding RNA genes. (B) Alternative splicing is regulated by splice site selection influenced by RNAbinding proteins and cis-regulatory elements. (C) All alternative splicing events result in functional protein isoforms. (D) Alternative splicing is primarily limited to the removal of introns without any variation in exon usage. (E) Alternative splicing is a rare event occurring in only a small fraction of eukaryotic genes.

21. Which of the following statements about chromatin structure is correct? (A) Euchromatin is associated with active gene transcription and is less condensed compared to heterochromatin. (B) Heterochromatin is enriched with histone H3 lysine 4 methylation (H3K4me3), promoting transcriptional repression. (C) The nucleosome is composed of DNA wrapped around a complex of six histone proteins. (D) Chromatin structure is static and does not change in response to environmental or cellular signals. (E) Histone modifications, such as methylation and acetylation, do not influence chromatin accessibility or transcriptional activity.

複選題22. Which of the following statements accurately compares translational initiation between eukaryotes and bacteria? (A) Bacterial translation begins with N-formyl-methionine carried by tRNA, which differs from the tRNA carrying interior methionine. (B) Bacterial translation requires the Kozak sequence to guide ribosomes to the start codon. (C) Eukaryotic translation requires the Shine-Dalgarno sequence to guide ribosomes to the start codon. (D) Eukaryotic translation begins with methionine carried by tRNA, which is the same as the tRNA carrying interior methionine. (E) Bacterial mRNAs contain a 5' cap structure.

複選題23. What are the functions of IF3 in bacterial translation? (A) Binds the 50S ribosomal subunit. (B) Promotes reassociation of the 30S and 50S ribosomal subunits. (C) Facilitates the binding of fMet-tRNA to the 30S initiation complex. (D) Facilitates mRNA binding to the 30S initiation complex. (E) Helps align the Kozak sequence of mRNA with the 16S rRNA.

25. Which of the following molecules do NOT function as GTPases? (A) IF2 (B) EF-G (C) EF-T's (D) EF-Tu (E) RF-3

26. Which statements inaccurately describe base pairing between codon and anticodon? (A) The first two bases in a codon determine coding specificity by forming strong Watson-Crick base pairs with the anticodon. (B) Isoaccepting tRNAs bind different amino acids but recognize the same codon. (C) Wobble occurs when the third base of a codon forms a non-Watson-Crick base pair with the anticodon. (D) Wobble allows the same aminoacyl-tRNA to pair with multiple codons. (E) The super-wobble hypothesis suggests that a single tRNA with U in the first anticodon position (5' position of the anticodon) can recognize codons ending in any of the four bases under certain conditions.

27. Which of the following antibiotics do NOT inhibit protein translation?(A) Puromycin(B) Thiostrepton(C) Penicillins(D) Chloramphenicol(E) Viomycin

28. The function of miRNA is based on inhibiting which of the following factors?(A) eIF1A(B) eIF2(C) eIF3(D) eIF4A(E) eIF4E

29. Which of the following is a primary function of the 3' UTR in eukaryoticmRNA?(A) Facilitating the initiation of transcription.(B) Determining the site of ribosome binding for translation initiation.(C) Regulating mRNA stability and translation efficiency.(D) Coding for signal peptides during protein synthesis.(E) Ensuring the proper splicing of introns from the pre-mRNA.

30. Which of the following best describes the function or characteristic of colicins? (A) Colicins are enzymes secreted by bacteria to degrade host DNA during infection. (B) Colicins are antimicrobial proteins produced by bacteria to kill or inhibit closely related bacterial strains. (C) Colicins are RNA molecules that regulate gene expression in bacterial populations. (D) Colicins are structural proteins involved in the formation of bacterial pili during conjugation. (E) Colicins are lipopolysaccharides that form part of the bacterial outer membrane.