複選題

27. BrdU is an analog of thymine that can be incorporated into double stranded DNA during  DNA  polymerization in S phase. Unsynchronized cells at various stages of cell cycle are first treate for 2 hours and then cultured in the absence of BrdU for another 4 hours. What would happen to those unsynchronized cells exposure to BrdU?
(A) BrdU is incorporated into all the unsynchronized cells.
(B) If a cell is labeled by BrdU, only one of the sister chromatins is labeled
(C) If a cell is labeled by BrdU, only one strand of DNA is labeled
(D) In the 2-hour BrdU pulse, only mitotic cells are labeled
(E) In the 2-hour BrdU pulse, only mitotic cells are not labeled

複選題23. The fluidity of lipid membranes in cells on depends on (A) temperature (B) the amount of unsaturated fatty acyl chain (C) the length of the fatty acid chain (D) the amount of cholesterol (E) the surface area of lipid membranes

複選題24. Proteins may non-covalently interact with small molecules such as GTP, , etc. Which of the following statement is/are NOT correct? (A) after first oxygen binding, hemoglobulin adapts a new conformation and could interact the second oxygen molecule better (B) neurotransmitter glutamate triggers calcium influx by non-covalently binding to calcium channel on the post-synaptic membrane. (C) facilitates the hemophilic interaction between E-cadherin (D) binding to either GTP or GDP activates small G protein, such as Ras. (E) when cellular ATP level is high, excessive ATP non-covalently binds to and inhibits pyruvate kinase, which mediates glycolysis and ATP production

複選題25. Proteins could be covalently modified by chemicals and small peptides, such as (A) phosphorus (B) ubiquitin (C) methyl group (D) acetyl group (E) Sumo

26. If you receive from your collaborator a DNA plasmid with a map shown below. Which of the following methods could help you to check if you have received a right plasmid?(A) Run the un-cut supercoiled form plasmid DNA in an agarose gel with DNA size marker. You find that the supercoiled plasmid migrates to the position between 5kb and 6 kb bands. (B) You digest the plasmid DNA with BgIII and run the cut plasmid DNA in an agarose gel with DNA size marker. You find that the cut plasmid migrates to the position between 5kb and 6 kb bands. (C) You digest the plasmid DNA with EcoRI and run the cut plasmid DNA in an agarose gel with DNA size marker. You find that the cut plasmid migrates to the position between 5kb and 6 kb bands. (D) You digest the plasmid DNA with BgIII and EcoRI. Then you run the cut plasmid DNA in an agarose gel with DNA size marker. You find 4.5kb and 738bp bands after double digestion. (E) Sequence the plasmid using a primer specific to mRFP.

28. The following diagram shows a family pedigree of a disease characterized by muscle weakness from (A) autosomal dominant (B) autosomal recessive (C) sex-linked dominant (D) sex-linked recessive (E) mitochondrial inheritance

29. DNA recombination refers to moving a DNA segment from one to another DNA molecule. This process (A) biogenesis of miRNA (B) linkage mapping human mutations that cause diseases (C) gene targeting, replacing a gene by a mutant allele. (D) tissue specific inactivation of a target gene by the Cre/loxP system. (E) to repair a DNA double strand break

30. Which of the following descriptions about exon, intron, 5' UTR, and 3' UTR is/are NOT correct (A) nonsynonymous mutation is a nucleotide change in exon that changes amino acid sequence of the encoded protein. (B) synonymous mutation is a single nucleotide change in intron that would never cause any change in the amino acid sequence of the encoded protein. (C) although not translated, the nucleotide sequence in the 5' UTR of mRNA corresponds to genomic sequence of exons but not introns. (D) although not translated, mutation in 3' UTR could profoundly affect mRNA stability. (E) mutation in intron sometimes affects protein sequence by introducing mRNA splicing errors.

複選題31. Which of the following descriptions about protein synthesis and targeting are correct? (A) ER (endoplasmic reticulum) targeting of proteins synthesized in the cytosol requires a N-terminus signal sequence. (B) Cotranslational translocation of proteins into ER lumen requires SRP (signal recognition particle) and the SRP receptor, and this protein translocation is energy-independent. (C) a-helix of the membrane spanning domains of proteins can function as a topogenic sequence and determine the orientation of the proteins on the membrane. (D) Most proteins in the mitochondria are encoded and synthesized in the mitochondria, and therefore do not need targeting sequences for mitochondrial localization. (E) Proper folding of proteins require posttranslational modifications.

複選題32. Which of the following about the cell nucleus and nuclear transport are correct? (A) Nucleolus is the major protein synthesis site in the nucleus. (B) Import into and export out of the cell nucleus require a nuclear localizing signal (NLS) and a nuclear export signal (NES), respectively. (C) The cargo-importin complex is cotransported into the nucleus with a GTP-bound Ran. It is the GTP hydrolysis in the nucleus that changes the Ran to the GDP-bound state and releases the cargo into the nucleoplasm. (D) The outer membrane of the nuclear envelope is continuous with the ER. (E) All protein components in the nuclear pore complex (NPC) undergo constant turnover and most have a short half-life.

複選題33. Which of the following approaches may help Michael determine the sequence of protein Q movements between the compartments X, Y and Z? (A) Sit down in front of the microscope, and follow the movements of GFP particles in live, unfixed cultured cells in real time. (B) Add another ligand that competes for the same receptor with protein Q, and measure the difference of GFP signals between compartments X, Y and Z. (C) Add GFP-protein Q to the medium at 4°C. Raise the culture temperature briefly to 37°C to enable endocytosis to occur, and then go back to 4°C again. After this treatment, do the immunostaining-GFP colocalization experiment at different time points. (D) Perform immunoEM to determine the exact localization of protein Q in X, Y or Z. (E) Purify individual intracellular compartments and determine the level of protein Q.