中山大学细胞生物学英文题库.doc

中山大学细胞生物学英文题库1. You think you might have discovered a new organelle using electron electron microscopy, but you are not sure if its real or an artifact of your technique. What might you do to prove it is real?a. Look for the structure in many similarly prepared specimens from the same source.b. Look for the structure in many similar prepared specimens from different sources.c. Look for the same structure in specimens prepared using different staining protocols.d. Look for the same structure in specimens prepared using different (or no) fixatives.2. Traditional genetic approaches to problems of cell biology have followed the path of information from gene to protein. Biochemical approaches have traced proteins back lto the DNA that encodes them, i.e., from protein to gene. This chapter has given you the basics to follow either path. Assume you are studying a problem relating to cell function. Briefly outline the basic steps you would take if you were starting with a gene and trying to deduce the function of the protein. Now outline the steps that you would take to get from a specific protein to a sequenced, isolated gene.1. Indicate whether the following statement is true or false. If it is false, expolain why in Nuclease-chypersensitive sites in chromation are located in the linker DNA between nucleosomes.(F)2. Short answera. Evolutionary conservation of histone proteins.b. nuclear matrix3. Suppose you discover a temperature-sensitive nutant whose nucleus failed to accumulate certain nuclear protein atan elevated (restrictive) temperature, but continued to accumulate other species. What conclusions might you draw about nuclear localization and the nature of this mutation?Cells possess more than one NLS. receptor that recongnize different localization sequences, and that the mutation was occuring in a gene that encoded one of these NLS receptor species.1. Fill in the blanks.A functional chromosome regrires the DNA sequence element at least one _ to permit the chromosome to copied one to facilitate proper segregation of its two copies at mitosis and two _ to allow the chromosome to be maintianed betwiin cell generations.(ARS; CEN)2. Which statemint best characterizes the nuclear localization signal?a. The NLS is tupically a small molecular weight metabolic intermediate. b. The NLS is a shetch of hydrophobic amino acids on a proteins N terminus.c. The NLS is one or two streches of basic amino acids on a proteins C-terminus.d. The NLS is a steroid that binds to DNA.(C)3. You suspect that a new hormone you are testing functions to stimulate myosin synthesis by acting at the transcriptioned level. What type of experimental evidence would support this contention. 1. Indicate whether the following statement is ture or false. If a statement is false, exlain why.a. Both myosin-! and myosin-! have a rollike tial that allows them to polymerize into bipolar filaments, which is crucial for moving groups of oppositely oriented actin filaments past each other.b. Sarcomere shortening is caused by the myosin filaments sliding past the actin filaments with no charge in the length of either type of filaments.2. If you treated cells with a drug that interferes with microtubuls such as colchrarne, which of the following would result?a. Cell shape would be disruptedb. Mitosis and merosis would not occurc. The intracellular location of organelles would be disruptedd. All of the above would result3. Some antibodies capable of binding to kinesin are able to block organelle movement, whereas other anti-kinesin antibodies seem to have bittle effect: How can you explain this obsenation?1.Would you agree with the statement that the centrosome plays a key role in determining that rates of lengthening and shortening of the microtubules of an animal cell? Why or why not?2.Compare and contrast the following cytoplasmic dynein v.s. Kinesin3.Differences in microtubular stability and function between different cells (or different locations within a cell) may be due to which of the following?a. the expression of different tubulin isformsb. the number of protofilaments composing a single microtublec. the presence of different MAPsd. all of the above1.What type of antibody could you use to distinguish between isolated coated vesicles that had formed at the TGN from those that had formed at the plasma membrane?2.Which of the body would you probably be the richest in HDL receptors?a. stomach cellsb. liver cellc. muscle celld. epitholial cells(D)3.A certain integral protein of the plasma membrane has two transmembrane domains in wihich both the C-terminals and the N-terminals are directed toward the cell extenor in the mature protein. Where are the C-termini located when the protein is newly translocated into the RER membrane? Into the Golgi? Into the vesicles?The nicotinic acetylcholine receptor is membrane-bound protein that also functions as a ligand-gated ion channel. Upon binding acetyleholine, the channel opens and sodi1. Fill in the blanks in the following statements:In cells treated with _ the Golgi appearatus largely disappears and the Golgi proteins end up in the ER, where they intermix with ER proteins.2. Indicate whether the following is true or false. (T)If a statement is false, explain why.All of the glycoprotions and glycolipids in intracellular membranes have their oligosaccharides facing the luminal side, whereas those in the plasma membrane have their oligosaccharides facing outside the cell.3. You have labeled the lipids on a patch of rough ER membrane with a fluorescent probe. After a few minutes, the probe shows up in the membranes of the cis Golgi. Now you treat the cells with the drug brefieldin A where might the fluoresent probe show up next?a. trans Golgi networkb. endoplasmic reticulumc. plasma membraned. secretory vesicles1. Fill in the following blanks:The amino-terminal ER signal poptide of a soluble protein itself have two functions. In addition to directing the protein to the ER mambrane, it also serve as a _.(起始跨膜信号)2. True of false: if false, explain why.In mammalian cells, the import of protein into ER begins before the polypeptide chain is synthesized, that is, it occures to co-translationality.3. Which of the following lack a signal sequence?a) acid hydrolase enzymes synthesized in macrophage cells.b) glycolytic enzymes synthesized in liver cells.c) polypeptide gormones synthesized in endocrine cells.d) antibody hormones synthesized in plasma cells.1.Which of the following explain why microsomes cant be seen viewed with eletron microscope?a) They are far too small.b) They are antifats of homogenization and centrifugation.c) They are transparent to electrons.d) They actually can be seen in election micrographics of cells.2.If you were to add a drug to interfere with the ability of ribosome to bind to mRNA, what effect would this be expected to have to the structure of the RER?3.Which, if any, of the following polypeptides would be expected to look, a signal peptide antibodies, acid phosphatase, hemoglobin, ribosomal protein, glycophorn.1.Would you expect the import of substances such as ADP or Pi to lead to a decrease in the proton-motive force? Why?Yes, because they occur at the expense of either the potential difference acress the membrane(in the case of the ATP/ADP exchange) or of the proton gradient (in the case of the uptake of Pi)2.Why would you expect the movement of protons into the intermembrane space to have an effect on the enzymes o fthe cytosol?Because the outer membrane is freely permeable to protons, therefore the protons concentration in the intermembrane space would rapidly epuilibrate with that of the cytosol, lowing the cytosolic pH.3.Using differential centrifugationm, you are trying to isolate peroxisomes and glyoxysomes from a mixture of cellular organelles. After a few centrufugation steps, you think you may have a relkatively pure suspension. How might you determine that your suspension does, indeed, have there organelles?a) Do an assay for the enzyme catalase.b) Do an assay for the enzyme succinate debydrogenase.c) Look in the microscope for a double -membrane bound organelle.d) Assay you suspension for nucleic acid.(A)1.Which of the following statements about the outer mitochondrial membrane is not true?a) The outer membrane is impermeable to hydrogen ions.b) The outer membrane is highly permeable to substances of small molecular weight.c) The outer membrane is about 50% lipid and 50% protein by weight.d) The outer membrane contains proins.2.Which of the follwing is not an electron carrier class in the electron transport chain?a) flavoproteinsb) cytochromesc) iron-sulfur proteind) cytochrome coxidase3.Short answer: Na-k ATPase from red blood cells can be made to synthesis ATP1. In most cases, RNA acts as an intermediary molecule between the genetic information and the final product of that information, proteins.What are the advantages of having an intermediary as opposed to translating the DNA directly into protein?2.The textbook states that the nucleotide sequence of splice sites is ancient origin. How do we know this sequence is ancient?a. It is widespread and occurs in even the most primitive eukaryotes.b. The number of mutations that have accumulated in the sequence indicates that it must have been in cells for millions of years.c. It is only found in organisms that are highly evolved.d. It codes for ancient proteins.3. If cultured cells are incubated with 14C-merhionine the radiolab will appear:a. in all the rRNAs simultaneously.b. first in the 45S RNA, followed by the 32S RNA, followed by the 28S RNA.c. first in the 45S RNA, followed by the 28S RNA, followed by the 5S RNA.d. first in the 28S RNA, followed by the 32S RNA, followed by the 45S RNA.1.Compare and contrast the folowing:(1) one gene-one enzyme vs one gene-one transcription unit.(2) upstream promoters vs internal promoters2.The signification of methylation of pre-rRNA is probably a. To ensure that the final rRNAwill assume the correct tertiary structre.b. To prevent the pre-rRNA from being processed.c. To prevent degredation of the parts destined to become mature rRNA.d. None of the above.3.The following complex of macromolecules is found in a cell: DNA attached to RNA polymerase, attached to a growing chain of RNA attached to a ribosome, attached to two tRNAs, attached to a growing chain of amino acids. The cell must be:a. A plant cell.b. An animal cell.c. A virus.d. A prokaryotic cell.4.The 5s rRNA differs from the other cellular rRNAs in which of the following ways?a. The genes are located outside the nucleolus.b. The genes are transcribed by RNA polymerase .c. The promoter region of the 5s rRNA gene is internal to the gene.d. All of the above.1. Ca2+, IP3, and cAMP are very different second messagers. In what ways are their mechanisms of action similar? In what ways are they different?2. Suppose that epinephrine and nonepinephrine could initate a similar response in a particular target cell. How could you show that the two compounds act by binding to the same cell-suface-receptor?3. If you break liver cells b homogenization separate the broken cell membranes (particulate) from the cytoplasm (sohuble) and add epinephrine to the soluble portion, the result will be a. the production of cAMPb. binding of the epinephrine to its receptor c. activeation of adenylyl cyclased. none of the aboveA gene encoding growth hormone in rats was introduced into mice. The construst used consisted in an open reading frame encoding rat growth hormone fused to a mouse promoter A. the growth hormone sequence was obtained from a rat cDNA library the only available source of sequence information. Fertilized mouse egg cells were transformed with the rat growth hormone construst and expression of the rat growth hormone was detected. Transformation of fertilized egg cells with rat growth hormone cDNA alone did not result in expression.1. Why was it necessary to fuse the rat growth hormone sequence to a promoter to obtain expression?a. The rat sequence was obtained from a cDNA library and therefore did not include a promoter sequence.b. No factors that recognized the rat promoter sequence were present in the mouse.c. The rat promoter was contained with the rat sequence but was inactivated in the mouse.d. Rat growth hormone is inactivated in mice.2. When the eggs were placed under conditions conducive to activation of the mouse promoter one of the resulting off spring grew large than the expected size. The appearance of the large mouse is consistent with one the following statements:a. That mouse grew bigger because it produced more mouse growth hormone.b. That mouse grew bigger because it was more aggressive and ate more mouse chaw.c. That mouse grew bigger because the mouse promoter A was activated result in increased production of rat growth hormone.d. The mouse grew bigger because his nose was longer.1. Neleic acid hybridization can be used as a measure of evolutionary relationships between species of the following statement about the DNA of related species, which is true a. Closely related species from hybrid DNAs with relatively low melting temperatures.b. Closely related species from hybrid DNAs with relatively high melting temperatures.c. There is no correlation between DNA hybrid meltiong temperature and relatedness of species.d. One cannot creat DNA hybrid molecules from DNAs of closely related species.2.Name techniques you might use to answer each of the following questions.a. Does the DNA on the hair found at the scene of a crime m