複選題

13. Please select all the correct description about M phase of cell cycle.
(A) Cyclin dependent kinase 1 (Cdk1) is the key kinase regulate the progression of M phase.
(B) Cellular DNA starts to replicate at M phase.
(C) The nuclear envelope starts to break down at prophase.
(D) The nuclear envelope starts to reorganize at nuclear port complex at telophase.
(E) The nuclear pore complexes are completely disassembled into single molecules before M phase.

9. A mutation that inactivates a regulatory gene of a repressible operon in an E. coli cell would result in _____.(A) continuous transcription of the structural gene controlled by that regulator (B) irreversible binding of the repressor to the operator (C) complete inhibition of transcription of the structural gene controlled by that regulator (D) continuous translation of the mRNA because of alteration of its structure (E) defects in cell division

10. The primary difference between enhancers and promoter-proximal elements is that enhancers _____.(A) enhance transcription; promoter-proximal elements inhibit transcription (B) are transcription factors; promoter-proximal elements are DNA sequences (C) are at considerable distances from the promoter; promoter-proximal elements are close to the promoter (D) are DNA sequences; promoter-proximal elements are also DNA sequences (E) are only identified in eukaryotic cells but not in prokaryotic cells.

11. To introduce a particular piece of DNA into a plant, you would most likely be successful with which of the following methods? (A) construction of a recombinant lambda phage carrying the specific DNA. (B) introducing a plasmid into the cell (C) infecting the plant cell with a Ti plasmid (D) transcription and translation (E) electroporation followed by recombination

複選題12. Which of the following status may reflect what we know about how the flu virus moves between species? (A) An animal such as a pig is infected with more than one virus, genetic recombination occurs, the new virus mutates, the virus is passed to a new species such as a bird, and the virus mutates again and can now be transmitted to humans. (B) The flu virus in a pig is mutated and replicated in alternate arrangements so that humans who eat the pig products can be infected. (C) An influenza virus gains new sequences of DNA from another virus, such as a herpesvirus; this enables it to be transmitted to a human host. (D) A farmer is infected by human flu and chicken flu viruses at the same time and the recombinant virus could become highly contagious and virulent for human. (E) There is no avian flu virus can directly infect human.

14. The product of the p53 gene _____.(A) causes cells to reduce expression of genes involved in DNA repair (B) inhibits the cell cycle (C) allows cells to pass on mutations due to DNA damage (D) slows down the rate of DNA replication by interfering with the binding of DNA polymerase (E) locates at the ribosome to ensure RNA translation efficiency

複選題15. Which of the following statements describes the lysogenic cycle of lambda (λ) phage are not correct? (A) The phage DNA is copied and exits the cell as a phage. (B) Most of the prophage genes are activated by the product of a particular prophage gene. (C) The phage genome replicates along with the host genome. (D) After infection, the viral genes immediately turn the host cell into a lambda-producing factory, and the host cell then lyses. (E) The lysogenic lambda can be induced into lytic cycle.

16. Bacterial cells protect their own DNA from restriction enzymes (endonucleases) by _____.(A) using DNA ligase to seal the bacterial DNA into a closed circle (B) adding methyl groups to adenines and cytosines (C) adding histones to protect the double-stranded DNA (D) forming "sticky ends" of bacterial DNA to prevent the enzyme (endonuclease) from attaching. (E) mutation of their genomic sequences to encode alternative proteins.

17. What information is critical to the success of polymerase chain reaction (PCR) itself? (A) The sequence of restriction-enzyme recognition sites in the DNA to be amplified must be known. (B) The sequence of restriction-enzyme recognition sites in the DNA to be amplified and in the plasmid where the amplified DNA fragment will be cloned must be known. (C) The complete DNA sequence of the DNA to be amplified must be known. (D) The DNA sequence of the ends of the DNA to be amplified must be known. (E) Similar Tm of both primers in the reaction.

複選題18. Which descriptions are correct for DNA replication. (A) The specific sites at which DNA unwinding and initiation of replication occur are called origins of replication. (B) The DNA replicated form a particular origin of the replication is a "replicaon". (C) Replicator sequences include initiator binding sites and easily unwound DNA. (D) Helicase loading is the first step in the initiation of replication in eukaryotes. (E) Mammalian DNA replication is semiconservative.

19. RNAi methodology uses double-stranded pieces of RNA to trigger breakdown of a specific mRNA or inhibit its translation. For which of the following might this technique be useful? (A) to destroy an unwanted allele in a homozygous individual (B) to decrease the concentration of a desired protein (C) to form a knockout organism that will not pass the deleted sequence to its progeny (D) to decrease the production from a harmful mutated gene (E) to facilitate a specific gene be transcribed and translated.